Acarology:

Proceedings of the 10th International Congress

Acarology: Proceedings of the 10th International Congress is a timely overview of the current international research mites and ticks. The outcome of a conference of leading acarologists, it presents major reviews of all current areas of research including:

*advances in acarine biodiversity and systematics

*human and livestock diseases transmitted by ticks and other parasitic mites

*interactions between mites and their food plants

*mites as biological control agents

*use of genetic markers in mite population studies

*mites as bioindicators

*ecology and biology of soil mites

*mite evolutionary ecology and reproduction

*advances in acarine diversity and systematics

The 90 papers in the book represent some of the best research from leading international researchers from over 50 countries, and helps to establish priorities for future research. All papers have been peer reviewed and edited.

Acarology is a comprehensive and important addition to the world literature on mites, and is an essential addition to all acarological and entomological reference collections.

    1. Page 3
      Abstract

      This paper reviews some of the historical trends in the development of acarology in Australia, from Linnaeus to the present. It includes brief biographies of some of the important acarologists of the past (Tryon, Womersley, Southcott, Lee, Roberts), and a few examples of long term research projects, on ectoparasites of grasshoppers, redlegged earth mite Halotydeus destructor, and cattle tick Boophilus microplus. The Australian mite fauna is shown to include 2,620 described and named species, and is estimated to include a total of 20,000 species.

    2. Page 17
      Abstract

      The plenary addresses given at previous International Congresses of Acarology are reviewed to gain an initial perspective on the status of the field during the last four decades. Salient progress in acarology, as indicated by organisational developments and high profile research successes, is reviewed. Some chronic problems and recent concerns for the discipline are discussed. An array of enquiries for future investigations are offered, and some future challenges for acarology are considered.

    3. Page 35
      Abstract

      Taxonomic studies on Prostigmata in New Zealand are reviewed. There was little taxonomic work on this group in the previous century and early this century. Most species have been described since the late 1940s, with a more rapid increase since the 1960s. Comprehensive revisions of Bdellidae, Stigmaeidae, Tenuipalpidae, and Tetranychidae were undertaken in the 1960s and early 1970s. Checklists were compiled by Lamb (1952a) and Spain and Luxton (1971). Monographs were produced on water mites (Cook 1983) and Eriophyoidea (Manson 1984a, b). A catalogue of New Zealand Prostigmata is currently being compiled. A total of 539 species has been reported, placed in 61 families and 219 genera. An additional 149 generic records have been reported without specific identification. The knowledge of many groups is poor or absent and more taxonomic studies are needed for the fauna.

    1. Page 43
      Abstract

      Within the Oribatida both very compact, nearly unsegmented forms and multiply-segmented forms can be observed, making it difficult to identify the most basic body divisions and segmentation. Moreover the basic segmentation type for Acariformes or for mites in general is still unclear. This paper discusses the alternative opinions of van der Hammen (since 1963), which are based on speculative comparative morphology of the Arachnida. The idea of a basic body plan of Acariformes with up to 17 segments is rejected and the older schemes of Grandjean (since 1934) appear to be more realistic. The different segmentation patterns within the Enarthronota are discussed and compared with Palaeosomata and other oribatid taxa, against a background of recent phylogenetic analyses. The most probable plesiomorphic hysterosoma in the early Oribatida is a type without segmental notogastral plates but with segmental setation. Basic Enarthronota had some erectile macrosetae on individual sclerites, found in some derived forms as intercalary setae e and f between plates. Nearly homonomous notogastral plates, as observable in Brachychthonioidea and in Haplochthoniidae, are probably secondary constructions.

    2. Page 50
      Abstract

      Relationships of the oribatid mite genus Hypozetes are assessed phylogenetically, using characters of adults and newly discovered apheredermous, plicate immatures. The closest relatives of Hypozetes are hypothesised to be among the Tegoribatidae (Achipterioidea) rather than among the Austrachipteriidae (Ceratozetoidea), as suggested in recent classifications. In addition, using characters of newly discovered plicate immatures, the genus Austrachipteria, is considered a member of the Achipteriidae (Achipterioidea), and Austrachipteriidae is placed in synonymy with Achipteriidae.

    3. Page 58
      Abstract

      Nothrolohmannia, the single nominal genus comprising the oribatid mite family Nothrolohmanniidae, is proposed as the sister group of the enarthronote genus Malacoangelia (Hypochthoniidae), based on 14 shared, derived character-states. By inference, the characteristic transverse notogastral scissure found in Malacoangelia and other hypochthoniid mites has been lost by fusion in Nothrolohmannia. A classification proposed to reflect this hypothesis includes both Nothrolohmannia and Malacoangelia in the Hypochthoniidae, subfamily Nothrolohmanniinae (new status). This relationship is a previously unknown example of the evolutionary plasticity afforded by the serial arrangement of plates in Enarthronota. Most enarthronote genera possess a specialised defensive morphology that includes two rows of erectile dorsal setae in transverse scissures, or else were derived from ancestors that possessed them. Several trends can be seen in two of the derivative taxa, Hypochthonioidea and Protoplophoroidea. One is the evolution of better cuticular armour (including mineralisation) and reduction of vulnerable transverse scissures, thereby replacing erectile setae as a defense mechanism. Another is the defensive ptychoid body form, convergently evolved from similar transitional morphologies in the two superfamilies. Another is a paedomorphic trend in the lineage containing Haplochthoniidae and Pediculochelidae, which has led to the loss of any noticeable predator defense. An appropriate classification of Enarthronota, and of Oribatida in general, will be a compromise that highlights, but does not overemphasise, this diversity in body form.

    4. Page 76
      Abstract

      Phylogenetic analysis of generic relationships in the mite family Acaridae allows hypotheses to be formulated concerning shifts in habitat preferences and host utilization over evolutionary time. The results of historical ecological analysis suggest that early derivative Acaridae inhabit vertebrate nests and use nidicolous insects for dispersal. A shift into the nests of primarily solitary bees and wasps resulted in the radiation of the Horstiinae. A second shift into the nests of primarily social insects (bumblebees, honey bees, ants and termites) resulted in the radiation of the Tyrophaginae. From a possibly termite-associated ancestor, a subsequent radiation of mites evolved away from close associations with host insects and into a wide variety of moist temporary habitats. Within the resulting radiation of the subfamily Rhizoglyphinae, habitat and host generalists, secondary specialists in very specific microhabitats as well as associations with particular insect groups have evolved.

    5. Page 83
      Abstract
      To whom correspondence should be sent

      It seems to be a common evolutionary phenomenon that closely related systematic groups display strong differences with regard to species numbers, diversity of inhabited biotopes and intensity of adaptive radiation. Parasitengonae (Acari: Prostigmata) provide apt examples for the examination of this phenomenon. These mites are known to inhabit a great variety of biotopes ranging from xeric to aquatic. Moreover, they display a considerable species-richness and diversity of organisation patterns. However, whereas some taxa (e.g. Erythraeoidea, Trombidiidae) are highly successful, others (e.g. Calyptostomatoidea, Johnstonianidae) are represented by low species numbers and they inhabit only a few biotope types.

      We here focus on the question of which organismal patterns have caused the evolutionary success of the whole group as well as of some subgroups, and which patterns have restricted the potential for adaptive radiation in others? Features that facilitate adaptations to different biotope types and modes of living are (1) Emancipation of the internal milieu from external conditions. This may be achieved by glands that seal body-openings by means of secretions, by morphological internalisation of body regions, by mechanisms allowing regulation of of the water- and ionic balance in a wide range of environmental conditions, by protective egg- or spermsheaths and by spermatophores having a stable water balance at various humidity conditions; (2) mechanisms allowing regulation of the water- and ionic balance in a wide range of environmental conditions; (3) a complex life-cycle including a parasitic larva and two calyptostatic nymphs. The parasitic larva increases the potential to disperse and to colonise patchy and/or temporary biotopes. Calyptostases allow complex metamorphoses and the development of strongly heteromorphic active instars which enable species to use different resources during ontogeny.

      A restricted potential for adaptation to new environmental conditions may be caused by the evolutionary loss of emancipatory structures and functions and the decrease of regulatory potentials. This may have evolved in the course of adaptation to a particular type of biotope (e.g. as in the hygrophilous Johnstonianidae). It may be also due to a character pattern that causes exclusion from many resources and habitat types as may be the case in the Calyptostomatoidea, being in some respects ‘living fossils’ when compared to its sister group Erythraeoidea.

    6. Page 100
      Abstract

      The phylogenetic relationships among prostigmatid families are far from being resolved. Previous analyses have focused entirely on morphological characters. The current paper is an attempt to identify a gene which can provide useful molecular data to address these relationships. DNA was extracted from mites representing 12 prostigmatid families. The polymerase chain reaction was used to amplify the V4 region of the nuclear 18S rRNA gene and two regions of the mitochondrial cytochrome oxidase I (COI) gene, and these fragments were sequenced. Phylogenetic inference using a variety of algorithms revealed strong support for nodes linking taxa within the same family but support for interfamily relationships was not significant. An exception is the close relationship of the Trombidiidae and Erythraeidae which was well supported. In a separate analysis the 18S rRNA sequences of the Prostigmata were combined with those of other chelicerates available in public databases. This analysis showed strong support for the monophyly of the Prostigmata.

    1. Page 113
      Abstract

      The belief that small size is positively correlated to high diversity has sustained a hypothesis of hyperdiversity in the Acari that has not been supported by studies of Northern Hemisphere acarofaunas. If mites are ‘megadiverse’, then acarine species richness in the tropics must be significantly higher than in other climatic zones. Based on studies in subtropical to tropical rainforests in Australia, this does appear to be true. Even extensive collections within strictly defined habitats do not adequately estimate local species richness, and sampling the same habitat across the landscape results in the continual accumulation of new species. The reasons for higher levels of acarine diversity in subtropical to tropical systems are not immediately apparent. Local assemblages of mites are characterised by small body size (e.g. adults of 52% of 415 species from a subtropical rainforest were less than half a millimetre in length), but this is also true of temperate zone assemblages. However, geographical and microhabitat distributions in tropical assemblages appear to differ significantly from those in temperate zone. These differences may reflect different levels of host diversity, host specificity, and microhabitat specificity in tropical mites.

    2. Page 121
      Abstract

      From samples taken at different localities in northern Germany during the years 1989–1997 it became evident that parasitengone mites belonging to the same genus often occur sympatrically. Thirty-seven species were found, belonging to 25 genera, of which 26 species were examined with regard to the validity of species status, their life history and their environmental demands. In all of the closely related co-occurring species, most characters (e.g. nutrition of postlarval instars) are only slightly differentiated or identical whereas interspecific differences were found concerning the parasitic phase of the larvae (e.g. host range, annual appearance of larvae). This is an indication of the strong selection pressure correlated with larval parasitism occurring today and which had occurred during the evolutionary history of the main parasitengone subgroups. The data show that those taxa of Parasitengonae which have retained the ancestral life-style and type of parasitic association, differentiation in larval parasitism has been the key process facilitating co-occurrence of closely related species in the same biotope.

    3. Page 136
      Abstract

      Aquatic mites are rarely included in biomonitoring studies or as indicators in themselves, despite several studies showing that they are sensitive to different types of pollution. The sensitivity of aquatic mites to urban pollution near Sydney, Australia was investigated to determine their potential as bioindicators. Mites were collected from six moderately polluted and six unpolluted rivers using kick samples in riffles and sweep samples in edges. The numbers of species and abundances of aquatic mites were far higher at the unpolluted than the polluted sites for both habitats. The numbers of species and abundances of aquatic mites were also significantly higher in edge samples than riffle samples for unpolluted sites. There was little overlap between the species collected from riffles and edges, demonstrating that each habitat had a distinct fauna. Analysis of Similarity showed that the polluted and unpolluted sites could be discriminated using the mite assemblage composition for both habitats. However, the results were not quite as significant as when family data for all macroinvertebrates were used. The results of this study suggest that aquatic mites could be very useful bioindicators, particularly for lowland rivers where riffle habitats are rare and the other macroinvertebrates collected from edge habitats are generally tolerant taxa.

    4. Page 143
      Abstract

      The faunas of ptyctimous mites of different subregions of the Oriental and Australian regions have been described and analysed. Similarity between the faunas of these and the neighbouring regions is statistically insignificant, the only common species being the widely distributed ones. No species has been found to occur only in neighbouring regions. Arguments are given to support the thesis that the Orient is the centre of origin and speciation of ptyctimous mites. The hypothesis that all genera originated before the breakup of Pangea, and that in some regions certain species underwent strong speciation and adaptive radiation, has been supported.

    5. Page 149
      Abstract

      Population biologists now have at their disposal new molecular tools with which to explore some questions that were difficult to address just 10 years ago. Among possible applications of these methods are the detection of sibling species and races, examination of genetic systems, tracing of the source of introductions, estimation of the level of migration, and gene flow between populations. These methods rely on the detection of genetic variation at individual genetic markers and the application of the methods of population genetics. Mitochondrial and nuclear variation in tetranychid mites are used to illustrate how different markers can provide different types of information about evolutionary biology, and to show the advantages of using a combination of different markers.

    1. Page 155
      Abstract

      In many taxa, courtship is neither a harmonious union of the sexes nor a masculine contest to impress females. Instead, females strive to retain control of fertilisation while males attempt to bypass female choice through deception or coercion. Here we discuss the mating biology of two clades of water mites (Parasitengona: Hydracarina), one exhibiting deceit (Unionicolidae) and the other coercion (Arrenuridae). Previous behavioural and cladistic studies of North American unionicolid species suggested that courtship could be an example of a ‘sensory trap’ in which male courtship takes advantage of pre-existing female sensitivities. We tested the robustness of the sensory trap hypothesis by adding several Australian species from previously unrepresented genera (Encentridophorus, Recifella) and subgenera (Neumania (Lemienia) sp.) plus one additional North American species of Neumania to the behaviouralcladistic analysis. The results neither support nor reject the sensory trap hypothesis, but rather maintain the ambiguity of the original conclusion. In some species of Arrenurus (Arrenuridae), possession of an intromittant device (the petiole) appears designed to bypass a female’s control over mate choice. We tested whether Arrenurus males with petioles (a) spent less time courting or (b) had simpler repertoires of courtship behaviour than males without petioles. There was no evidence of shorter courtship time in modified males; however, the least complex courtship occurred in a petiolate species and the most complex in an apetiolate one. More sensitive measures of courtship effort and complexity are required to thoroughly test this hypothesis.

    2. Page 170
      Abstract

      Parthenogenesis in the family Acaridae was examined through literature records and laboratory cultures of several species. Live specimens of parthenogenetic species of Schwiebea and Thyreophagus were collected in Japan, and Sancassania and Acotyledon formosani from Japan were documented as parthenogenetic. The type of parthenogenesis was thelytoky in all species. We hypothesise that parthenogenesis evolved in these genera independently. Experiments compared life-history traits for two pairs of sexual and asexual species of Schwiebea (similis-group and lebruni-group). Asexual species exhibited either higher fecundity or faster development than their sexual relatives, but not both. It was hypothesised that related sexual and asexual species can coexist because they segregate their habitats and niche in the field. The asexual species conform to theory in inhabiting aquatic situations. The asexual S. elongata was assumed to have speciated relatively recently because potential habitats often overlapped with those of its sexual relative, and the male was retained. On the other hand, the lebruni-type mites seemed to represent a longer separate history because they are morphologically more distinct and occupied different types of substrates.

    3. Page 176
      Abstract

      Males of an undescribed astigmatic species of the algophagid genus Hericia demonstrate precopulatory contact mate-guarding behaviour. Adults are sexually dimorphic, and most of the morphological differences found in males are associated with guarding behaviour. In this regard, coxae IV of the male are located ventrally and mesiad of coxae III, thereby resulting in legs IV taking a position directly below legs III. Legs IV are also bowed ventrally and can be rotated forward to form a ‘basket’ under the idiosoma. Males use their baskets for ‘scooping’ up quiescent tritonymphal females and holding them securely under their idiosomas. Males thereby guard immature females until they ecdyse to adults, at which time mating takes place. Some males were observed guarding adult females for extended periods of time, presumably after copulation. It is therefore possible that this species also exhibits post-insemination mate-guarding behaviour, however details concerning this behavior are poorly known.

    4. Page 180
      Abstract

      Direct sperm transfer is shown to occur in Homocaligus amphibius Wainstein, 1975, a member of the raphignathoid mite family Homocaligidae Wood, from mites cultured in the laboratory. The female/male ratio in the studied population was approximately 1:2. Insemination in this species is direct, and is achieved by direct contact of the genital organs. A complex reproductive behaviour (guarding, initiation of females to sperm intake, male competition) is demonstrated. This complex reproductive behaviour can be considered as a preadaptation to a specific translocal environment of the fresh-water shore-line edge.

    1. Page 185
      Abstract

      Twenty-two previously described species and four undescribed species of bat wing parasites in the genus Periglischrus (Spinturnicidae) were analysed from a new morphological point of view. Some elements considered here proved to be important in the taxonomy of Periglischrus, such as the different distribution patterns of foveae on the dorsal shield, the size and proportions of the proteronotal setae, and the presence or absence of a coxal ridge. These were all good markers to define two principal evolutionary trends: (1) the acutisternus-clade, associated mainly with Phyllostominae and Macrotinae bats; and (2) the caligus-clade, associated mainly with Glossophagini, Stenodermatini and Desmodontinae bats. Furthermore, the outline and ornamentation pattern of the dorsal shield, the outline of the sternal and sternogenital shields, and some idiosomal chaetotaxy, were useful to redefine eight species groups in both clades. In addition, it is confirmed that Periglischrus natali is quite different from mites of the genus Periglischrus, and must therefore be considered to belong to the previously recognised genus Mesoperiglischrus.

    2. Page 196
      Abstract

      The morphology and fine structure of the genital system of overwintering females in two species of Typhlodromus are described by means of light and transmission electron microscopy. An unpaired ovary is present in the idiosoma, posterior to the ventriculus, dorsal to the colon and anterior to the postcolon. Dorsally, the ovary displays a central dome-shaped elevation, the camera spermatis, and the oocytes seem to be subglobular in cross section with a distinct roundish nucleolus. The soma cells of the camera spermatis support and surround the oocytes. The camera spermatis is connected ventro-laterally with the lyrate organ, which is provided with two arms that are in contact with the ovary. The arms reach the dorsal region of the idiosoma, extend anteriorly as far as coxae III, and lie between the posterior caeca and the ventriculus. The lyrate organ presents large cells provided with a very distinct nucleus. These cells make up a nutritive tissue connected to the oocytes by nutritive cords that extend into the camera spermatis. The ovary continues ventrally into the oviduct I, which has a lumen with prismatic cell walls. Oviduct II (vagina) leads to the genital orifice and has cuticle-lined walls.

    3. Page 203
      Abstract

      The female reproductive system of Sarcoptes scabiei is described using light and transmission electron microscopy. The system consists of two functional units: a sperm storage and transport component, and a pair of ovaries and a shell gland. The two units are not directly connected so that sperm must migrate through female tissues to reach the ovaries. The ‘nutritive’ type ovary consists of a large central cell surrounded by developing previtellogenic oocytes which are connected to the central cell via cytoplasmic bridges. Oocytes are fertilized in the ovary before moving to the paired oviducts where chorion formation and vitellogenesis take place. These two processes are carried out by the oocyte in that nurse and follicle cells are absent, and the ovary wall is non-secretory. The oviducts converge on the shell gland which is made up of two cell types. Type 1 cells apply their secretory granules to the outer surface of the chorion to form an exochorion. Thus, the egg shell is a bipartite structure of dual origin. Release of the secretory material of Type 2 cells was not observed. The shell gland is the only part of the reproductive tract with intrinsic musculature. Mature eggs pass to the outside through the cuticle-lined vagina.

    4. Page 213
      Abstract

      We propose the use of confocal laser scanning microscopy (CLSM) to examine the shape of the pharyngeal pump complex in Pygmephoridae in order to distinguish among different genera and to distinguish among closely related species within genera. Heavily sclerotised structures in the exoskeleton obscure the real shape of the pharyngeal pump complex when using conventional light microscopy. The shape of examined pharyngeal pumps depended on the orientation of the gnathosoma of the mites after mounting. However, by making use of the muscular pharyngeal pump units that autofluoresce when illuminated with light of the correct wavelength, one is now able with CLSM to compile 3D virtual images of these structures and rotate them about different axes in order to determine their real shape.

    5. Page 217
      Abstract

      Some of the sense organs on the tibio-tarsus of leg I of a phoretomorphic female of Pediculaster mesembrinae (Canestrini) (Pygmephoroidea: Siteroptidae) and on tarsi I and II of Phytoptus avellanae Nalepa (Eriophyoidea: Phytoptidae) were studied using transmission and scanning electron microscopy. The siteroptid solenidial shaft consists of a multiporous wall enclosing several dendritic branches. Its sensory components include a varying number of neurons depending on the particular solenidion on the leg. No tubular bodies are associated with this sensory structure. By contrast, the shaft of the phytoptid solenidion has very small apical pores and an aporous outer surface along its length. The solenidion on tarsus I has four neurons, and that on tarsus II has three. The outer dendritic segments are unbranched, penetrate the shaft and run up to its apex. As with the siteroptid, no tubular bodies are associated with this structure. These ultrastructural features are consistent with a chemoreceptive role involved in mite trophic activity and behaviour. In particular, the phytoptid solenidion is assumed to be gustatory, while an olfactory role is suggested for the structurally different siteroptid solenidion. In addition, ultrastructural descriptions are given for the tarsal setae and the empodium of P. avellanae, which have mechanoreceptive roles.

    6. Page 226
      Abstract

      After special treatments, such as microwave fixation and enhanced osmification according to the osmium-thiocarbohydrazide-osmium technique, it is possible to separate internal organs of astigmatic mites by treatment in a commercial ultrasonic-cleaner device. Their microanatomy can then be investigated by scanning electron microscopy. This technique is a good tool to demonstrate different organs without large expenditure. A detailed description of the microdissection technique is given and the results are illustrated by means of the nervous, musculatory, digestive and reproductive systems of Glycyphagidae.

    7. Page 230
      Abstract

      Cuticular mineralisation by calcium carbonate or calcium oxalate occurs in various primitive and derived taxa of oribatid mites. We applied transmission and scanning electron microscopy to determine the nature of cuticular chambers in certain members of Enarthronota, and the involvement of these chambers in the deposition of minerals. In almost all cases, chambers were associated with the epicuticle and were filled with deposits. In Eniochthoniidae and Mesoplophoridae the chambers form caverns within the epicuticle; they are associated with all hardened cuticle of the body surface, and are clearly the site of calcium oxalate deposition. In Hypochthoniidae (including Nothrolohmannia) chambers are instead modifications of epicuticular indentations above pore canals, and the deposited mineral is calcium phosphate (probably apatite). Distribution of chambers varies within the family. In Hypochthonius they are in patches of various sizes and at various locations on the body and legs, while in Malacoangelia they are more generally distributed. The porose notogastral organs of Malacoangelia and Nothrolohmannia have extended pore canals that contain material similar to that of the chambers. Examined Lohmanniidae have cuticular chambers like those of Hypochthoniidae, and their distribution forms the pattern of transverse bands that has wrongly been considered evidence of primitive segmentation.

    8. Page 242
      Abstract

      The leg setal ontogeny of a caligonellid mite is presented for the first time. Leg chaetotaxic notations and their relative positions in larva and adult legs are illustrated establishing setal homologies with those of the Stigmaeidae, Raphignathidae and sister families in the Acariformes. It is hoped that other workers will be stimulated to look closer into leg chaetotaxy because there is a wealth of anatomical information extremely useful in further understanding of Acari systematics and phylogeny.

    9. Page 250
      Abstract

      The presence of an alarm pheromone is demonstrated for the first time in the deutonymphal stage of the oribatid mite, Nothrus palustris (C. L. Koch). The active principle is identified as geranial (3,7-dimethyl-[E]-2,6-octadienal, active at 10–100ng).

    1. Page 255
      Abstract

      Reproductive and nutritional biology of the oribatid mite Tectocepheus velatus were studied in populations inhabiting five adjacent or approximate biotopes in the Czech Republic – agroecosystem, shrubland, calcareous steppe, grassland and pine woodland – over two years. No males were found, and most adult females were gravid with one or two eggs. The juvenile/adult ratio fluctuated during the year and reached higher values at sites with higher value of dominance of T. velatus. Food consumption dynamics and food types did not vary seasonally, and were similar in all biotopes studied. With histological methods, food was observed throughout the year and in all parts of the alimentary tract in all juveniles. In adults, two basic types of food bolus were found: (1) a compact bolus with a surface coat, which sometimes contained hyphae and spores, and (2) a loose substance without any membrane. Bacteria were observed in the mesenteron. Hemocytes were more obvious in specimens with food in the alimentary tract. Thus, among the populations studied the nature of the biotope, including anthropological influences, has a negligible effect on the nutritive and reproductive biology of T. velatus.

    2. Page 262
      Abstract

      Oribatid mites perform an active role in the decomposition of organic matter and serve as an important element in the humification process in the soil ecosystem. We examine the potential role in biodegradation of two common species of these mites that represent the important families Phthiracaridae and Lohmanniidae. Individuals of Hoplophthiracarus rimosus Mahunka, 1978 and Lohmannia n. sp. were subjected to a series of laboratory and field studies including food choice tests, gut content examination, enzyme analysis and assessment of nutrients in litter before and after consumption by these mites. Results of food choice tests and gut analysis clearly showed the ability of the two species to degrade higher plant material, particularly woody elements by H. rimosus and leafy components by Lohmannia n. sp.. This was further confirmed through enzyme assays, which demonstrated the release of cellobiase by both species. Concentrations of the macro and micronutrients N, P, K, Fe, Mn, Cu and Zn were significantly higher in litter of Artocarpus integrifolia, after it had passed through the gut of the two study species, confirming the positive involvement of these mites in litter degradation.

    3. Page 266
      Abstract

      Microbial communities commonly shift between fungal and bacterial dominance, but little is known of how the mites associated with such communities respond to these changes. Two mite species, Trichoribates trimaculatus (Oribatida) and Tyrophagus putrescentiae (Acaridida), which are respectively algophagous and mycophagous, were subjected to two moisture regimes in laboratory cultures using algal-covered bark as substrate and initial food source. Data were collected by histology, faecal pellet investigation and enzyme activity tests, and several phenomena were noted; (a) The mycophage gradually adapted to feeding on invading microbes, but the algophage did not; (b) Palatable food can be harmful under some circumstances (high moisture); (c) When palatable food is not available, excrements and bacteria, which have a low nutritional value for mites, can be substituted; (d) Feeding activity of the mycophage ameliorated culture conditions for the algophage, indicating that mycophages play an important role in the balance of simple mite communities, at least under experimental conditions; (e) The pattern in which species are introduced (together or separately) is a significant factor affecting the processes in simple mite communities.

    4. Page 269
      Abstract

      Talus formations are distinct biotopes that previously have not been recognised and included in acarological field research. Sampling at 51 talus formations in the Czech Republic and Austria resulted in the collection of 34 species of the predatory mite family Rhagidiidae. Most of these are psychrophilous species known from such habitats as woodland or meadow litter, but six are new to science and several represent unusual, disjunct populations. Among the latter are Rhagidia gelida, R. breviseta, R. parvilobata, Coccorhagidia pittardi and Poecilophysis recussa which were previously known only from colder climates, and Foveacheles terricola, which was previously known only from caves.

    5. Page 272
      Abstract

      To test the hypothesis that passalid beetles (Coleoptera: Passalidae) have an exceptionally high diversity of symbiotic mites, I analysed species assemblages of Mesostigmata on large (> 1 cm) arthropods living within and beneath rotting logs at four sites in sub-tropical rainforests and three sites in tropical rainforests in Queensland, Australia. In total, I collected 740 log-inhabitants, representing about 42 species from 17 families. Passalid beetles were the most commonly collected log-inhabitant (426 individuals; 9 species); cockroaches, scarabaeid larvae and millipedes were also common. Of the 42 species of log-inhabitant, 29 carried at least one species of Mesostigmata, and I collected a total of 9374 mites, representing 71 species from 14 families. After removing the effects of the abundance of passalid beetles, they still had more species of mites associated with them than all of the other log-inhabitants combined. The diversity of mites on the Passalidae is at least double that of any other family of log-inhabitant. Indeed, if the number of associated mite families (24) is considered, Passalidae may have one of the most diverse assemblages of mites found on any family of animals.

    6. Page 277
      Abstract

      This work examined the reaction of soil mites to deforestation and fire down to 15 cm depth, in a yellow latosol one-hectare primary forest plot prepared for a biomass burning experiment. It had been totally cut and its plant biomass left on site, drying for three months. Soil cores were collected from a non-disturbed neighbouring forest and, from the site before and after the fire, at weekly and monthly intervals during the first year and once during the fifth year after burning. Results are reported for the general soil fauna during the entire period and data on identification of mites include the following collections: logged forest, one day, two weeks and one year after burning. Acari made up 79% of the total fauna in the control forest, 90% in the logged plot, 35% one day after burning, 77% two weeks after burning, 95% one year after burning and 68% five years after burning. One-year after burning population densities increased at all three depths. Only five years after burning did group diversity reach numbers similar to those of non-disturbed forest, but instability of the system persisted. Long-term site monitoring is being conducted.

    7. Page 283
      Abstract

      As adult Oribatida and Uropodina are well sclerotised, it has been assumed that most predation is limited to the immature stages; however, some mites, ants and beetles have been observed feeding on armoured mites. We studied scydmaenid beetles (Coleoptera: Scydmaenidae) from rainforest in south east Queensland and tested the hypothesis proposed by Schmid (1988) that scydmaenids are restricted to armoured mite prey. Of the 43 scydmaenids that we observed in small arenas, 32 (74%) fed on armoured mites. These included representatives of at least five genera and 22 morphospecies; however, 15 individuals (representing three of the five genera) also scavenged on dead arthropods such as ants and springtails. Although some Australian species of Horaeomorphus and Stenichnus appeared to be specialised on Oppioidea (Oribatida), certain species of Euconnus were extreme generalists feeding on many types of armoured Oribatida and Uropodina. Additionally, we observed predation on armoured mites by Enicocephalidae (Hemiptera), but not by Pselaphidae (Coleoptera).

    1. Page 291
      Abstract

      The false spider mite, Brevipalpus obovatus Donnadieu, is a major pest of fruit trees and ornamental plants in Egypt. This work was directed at studying the seasonal abundance, host related biology and field control of B. obovatus. Populations of B. obovatus on citrus trees were monitored for 12 months. Populations peaked in early spring and fall at an average of 0.71±0.02 and between 0.52±0.04 and 0.61±0.02 mites/leaf, respectively. B. obovatus was reared on citrus and mint leaves in the laboratory conditions (25±2-C and 65±5% RH) and the duration of developmental stages was measured. The mean incubation period was 3.07 and 4.16 days on citrus and mint, respectively. Hatch rate was 87.49% and 72.9% for the two hosts. The active larval, protonymphal and deutonymphal stages lasted an average of 2.76, 2.63 and 3.21 days on citrus, and 3.13, 3.23 and 4.53 days on mint. Female longevity averaged 34.26 and 41.16 days on citrus and mint, respectively. Fecundity was also observed for five generations. The effect of two acaricides, Ortus (fenpyroximate) and Neoron (bromopropylate), on B. obovatus were evaluated in citrus orchards in the Tahrir area, Egypt. The results indicated that Ortus reduced the mite population faster than Neoron.

    2. Page 295
      Abstract

      Twenty two species of grain legumes from four genera that are important or potentially important to Australian agriculture were examined for their response to feeding by redlegged earth mite (Halotydeus destructor) under controlled conditions. Special attention was paid to differences among species within a genus. Plants were exposed to mites at the seedling stage and feeding damage scored one week and two weeks after mite application. The results showed that within the genus Lupinus, lines of yellow lupin (L. luteus) had the highest feeding scores, while mites fed less on lines from narrow-leafed lupin (L. angustifolius). Lines from albus lupin (L. albus) and rough seeded lupins (L. atlanticus, L. cosentini, L. pilosus) suffered minimal attack by mites. H. destructor feeding damage also differed between species from the genus Vicia. V. sativa was attacked most, while V. ervillia and V. articulata were fed on very little. Five species from Lathyrus differed in levels of H. destructor feeding damage. L. tingitanus and L. ochrus were fed on most. L. cicera and L. sativus were fed on very little. Species and subspecies from Pisum were readily damaged by H. destructor feeding, with no significant variation among them. It is unlikely that the same mechanisms cause resistance to H. destructor over such a range of species. Mite feeding was clearly affected by interspecific variation within genera. A better knowledge of the mechanisms involved will assist selection and breeding of crops showing resistance to this pest.

    3. Page 300
      Abstract

      The overwintering populations of Panonychus ulmi and Aculus schlechtendali showed small variations in densities on three different cultivars of apple, Aroma, Summerred and Gravenstein. The summer population densities of P. ulmi and A. schlechtendali were significantly different on the different cultivars. Aroma had the highest number (21/leaf) of P. ulmi per leaf at the end of June. On the other hand, Summerred showed the highest (936/leaf) numbers of A. schlechtendali per leaf in the middle of August. There was a gradual increase in the density of A. schlechtendali during the study period.

    4. Page 306
      Abstract

      Studies on the physiological and biochemical aspects of mite-plant interactions were conducted on different host plants: chrysanthemum, bean and cucumber growing under greenhouse conditions or in the open. The growth of plants injured by mites was studied after different periods of mite infestation. It was found that mite populations at low densities can stimulate the growth of injured plants as well as their photosynthetic activity by about 10–15% compared to uninjured plants. Photosynthetic activity in strongly injured leaves of experimental plants was much lower than in uninjured leaves. The decrease in CO2 assimilation was positively correlated with chlorophyll reduction and disturbance in assimilate distribution. The oxidative processes in leaves of injured plants were very active during the entire period of mite feeding. The rate of dark respiration was about 20% higher in leaves infested with mites compared to uninfested leaves. The activity of oxidative enzymes, peroxidase (1.11.1.7 and polyphenol oxidase (1.10.3.2) in mite infested cucumber plants was increased as a result of mite feeding. It created a suitable situation for the oxidation of phenolic compounds. The content of soluble sugars in injured leaves after a short period of mite feeding was usually low, while their production, translocation and accumulation into starch were accelerated. At the beginning of mite feeding the amino acids concentration in injured chrysanthemum leaves was lower than in healthy leaves, and increased as mite injury became greater. Changes in the concentration of amino acids were also observed in injured cucumber leaves. During a period of mite feeding some changes in the concentration of primary and secondary metabolites in the host plant can be connected with defence reactions of the host. Differences in the reactions of susceptible and resistant varieties were also noticed.

    5. Page 314
      Abstract

      Resistance to spider mites has been found in a number of Gossypium species, including G. barbadense, G. arboreum, G. herbaceum and G. australe. Among the cultivated cottons, G. hirsutum has several morphological and biochemical traits that confer partial resistance, while G. barbadense varieties show high antibiosis to T. urticae. Within G. hirsutum, both constitutive and induced components of plant resistance have been identified. Genotypes with lower sugar and starch content are generally poorer hosts for spider mites. Genotypes with elevated levels of condensed tannins are often, but not always, more resistant to spider mites. G. hirsutum also shows induced resistance in response to prior mite feeding or mechanical damage. Morphological traits associated with resistance include a thicker spongy parenchyma layer, which reduces mite stylet penetration of the palisade, and a more lobed leaf shape or glabrous leaf surface, which provide less protection for mite eggs. Genotypes with very hairy leaf surfaces are more resistant to spider mites because they interfere with mite movement. It is important to consider that some plant resistance traits for mites may conflict with resistance to other pests, with the needs of beneficial insects, with the development of acaricide resistance and with the needs of cotton processors.

    6. Page 328
      Abstract

      Halotydeus destructor (Tucker) (Acari: Penthaleidae) is a major pest of pasture legumes in southern Australia. The mites live on the soil surface and move up to the canopy of pasture legumes to feed. H. destructor feed in aggregations. They aggregate more on cotyledons previously damaged by mites or artificially damaged than on undamaged cotyledons, probably attracted by low concentrations of the volatile compounds generated as a consequence. The development of resistant pasture legumes is a priority for reducing damage. A case study of resistance mechanisms on subterranean clover is reviewed. Two mechanisms of resistance are found in cotyledons, one is due to physical strength of the epidermis, and the other is due to the production of high levels of a green leaf volatile, 1-octen-3-one. In trifoliate leaves the plant seems to depend on the isoflavonoid constituents which have accumulated in the leaves, and in particular those on the leaf surface, perhaps associated with trichomes. The use of these mechanisms is being tested as markers for breeding programs.

    7. Page 342
      Abstract

      Eriophyid mites have many attributes that make them of interest for the biological control of weedy plants, among them a restricted host range. A critical part of any biological control program is to test the host-range of candidate agents to establish the level of risk posed to non-target plants, and ensure that agent releases will not do more harm than good. This provides valuable data for studies of host choice by the mites and of host-plant susceptibility within the preferred host range. Two cases are considered here; that of Eriophyes chondrillae, a gall-forming species used for the biological control of skeleton weed, Chondrilla juncea, in Australia, U.S.A and Argentina, and Aculus hyperici, a non-gall forming species, recently introduced into Australia for the control of St John’s wort, Hypericum perforatum. Populations of both weed species show differential susceptibility to attack by their respective mite phytophages. The expression of variation in host-plant susceptibility in the two cases is compared and contrasted.

    8. Page 349
      Abstract

      Petrobia latens, a phytophagous pest mite, cosmopolitan in distribution, infests mainly wheat Triticum aestivum, and barley Hordeum vulgare, in semi-arid zones of Rajasthan. It is prevalent in arid regions all over India, especially in the states of Rajasthan, Haryana, Delhi, Punjab and Madhaya Pradesh. Its abundance is high in the winter, reaching peak infestations in February-March, particularly when dry sunny prolonged winters occur. Feeding damage causes leaves to wither, as chlorotic spots enlarge and developing grains become shrivelled. The result of the studies conducted on the effect of the nutrients nitrogen, phosphorous, potash, zinc, boron and iron., and soil salinity ranging from Ec 0.26 to 10.20., and p. 8.60 to 10.30 showed that the population of P. latens was minimal (10.3 mites/10 cm2 slide area) in plots treated with zinc and maximal in untreated controls (25.4). Mite incidence was minimal (0.2 mite/10 cm2 slide area) at high salinity (Ec 5.57 and p. 9.4), and maximal (1.9) at low salinity (Ec 0.26 and p. 8.6).

    9. Page 352
      Abstract

      The life history and population development of Rhyncaphytoptus negundivagrans Farkas were examined by collecting weekly leaf samples from box elders. It was found that R. negundivagrans has a complex life history. At the end of May, the reddish-brown deutogynes left over-wintering sites and appeared on the underside of the leaves. They laid eggs which hatched into cream-coloured protogynes and males. The protogynes continued reproduction throughout summer, and the mite population density reached its maximum level in July. A low number of the deutogynes which occurred in summer migrated to over-wintering sites. From mid-August on, the deutogyne population increased, while the protogyne population decreased. The deutogynes moved to dry bark crevices for hibernation and the mites disappeared from leaves at the end of October.

    10. Page 355
      Abstract

      The Kanzawa spider mite, Tetranychus kanzawai Kishida, and the two-spotted spider mite, T. urticae Koch (green form), are both important pests on pea and watermelon in Wakayama, Japan. In August and September, T. kanzawai maintained a low-density population on the non-cultivated host Clerodendrum trichotomum in the border vegetation, and then dispersed into pea fields when peas were sown. The T. kanzawai population increased in density in pea fields, reaching a peak in November or December. T. urticae were not observed on border vegetation but lived on chrysanthemum during the summer, moving into pea fields in September. T. urticae occurred on chrysanthemum throughout the year, including the cultivation and nursery period. T. urticae continuously reproduced only on cultivated plants, which were under acaricide application year round, whereas T. kanzawai occurred on both cultivated and non-cultivated plants, resulting in the resistant population mixing with the susceptible population on border vegetation. These differences in their life cycles could explain the differences in susceptibility between the two mite species; T. urticae has developed high resistance to acaricides while T. kanzawai has remained susceptible.

    11. Page 361
      Abstract

      A recent study of mite – honeybee interactions in Kerala found Neocypholaelaps stridulans (Evans) (Acari: Ameroseiidae) interacting with worker bees and coconut inflorescences. Occurrence of female mites was recorded first on worker bees and hives of Apis cerana F. and Apis mellifera L. Later a range of populations of the mite was encountered on coconut inflorescences. Incidence of the mite on 3 varieties of coconut namely, chowghat green dwarf (variety-I), D X T hybrid (variety-II) and chowghat orange dwarf (variety-III) was examined from June 1995 to August 1997. Intense oviposition and population explosion of the mite was observed on the inflorescences of variety I. Peak population of the mite was observed on the inflorescences 1 to 2 weeks of age, and the activity of the mites appeared to promote button fall. Variety III showed the lowest population density of the mite. Analysis of the population densities of the mite among the 3 varieties showed a low susceptibility of variety III to mite infestation. Adult female mites were found utilising worker bees for transportation and dispersal.

    1. Page 369
      Abstract

      This paper reviews several rhabdovirus or rhabdovirus-like diseases (e.g. the virus causing leprosis on citrus and coffee ring spot on coffee, Ligustrum ring spot, green spot on passion fruit, orchid fleck, and the symptoms of zonate chlorosis) and their associated mite vectors in the genus Brevipalpus (Tenuipalpidae). B. phoenicis (Geijskes), B. obovatus Donnadieu, and B. californicus (Banks) have been identified as vectors in the transmission of one or more of these diseases. Two important crops, coffee and citrus, are affected by coffee ring spot and citrus leprosis, respectively. Presently, leprosis is the major virus disease of citrus in Brazil and coffee ring spot, after many years as a non-economic disease, caused serious economic losses in Minas Gerais State in Brazil during 1995.

    2. Page 376
      Abstract

      Eight species of mites in the family Tydeidae were identified from seven citrus groves located in central and south central Florida. Lorryia formosa was the most abundant species and was found in all parts of citrus trees, on one vine, and on ground cover plants beneath the trees. Orthotydeus gloveri, Tydeus mumai, Afrotydeus munsteri, Homeotydeus near shawi, Parapronematus near acaciae, Apopronematus sp. and Metapronematus sp. were the other species found in association with citrus. All occurred at lower densities and had restricted distributions within citrus trees.

    3. Page 381
      Abstract

      Biological control of spider mites (Tetranychus urticae Koch and T. ludeni Zacher) in Australian field-grown strawberry crops using the predatory mite Phytoseiulus persimilis Athias-Henriot, has been practised commercially since 1984. Although adoption was slow in the early years, a significant number of growers now use the system. The adoption rate increased through the involvement of private consultants in pest monitoring and management. Increased confidence of growers in biological control of spider mites has led to the recent acceptance and implementation of the ‘pest-in-first’ (PIF) technique first proposed in 1984. The method of semi-random distribution of predatory mites into a strawberry crop was based on the assumption that a reasonable proportion of the introduced predators will be deposited either close to, or in, plants infested with spider mites, and that the predators will become established and disperse quickly enough throughout the crop to prevent spider mite outbreaks. Regular monitoring and good timing of releases are necessary for this system to work effectively. This degree of management has often been lacking on farms unless consultants were involved. The ‘pest-in-first’ technique involves the artificial infestation of marked plants within the strawberry crop with spider mites. When they have established, P. persimilis is introduced into those plants. Although ‘pest-in-first’ still requires good management, it is simpler to employ, is more cost effective and the results are more positive and predictable. It also allows programmed management of other pests with minimal impact on predatory mites, and assists predator suppliers to plan production.

    4. Page 387
      Abstract

      Current glasshouse biological control practice relies on regular prophylactic introductions of one or two ‘best’ species of natural enemy. Whilst this is effective for much of the time, occasional failures occur due to factors such as differences in response to seasonal changes in environmental conditions, and/or host-plant effects. This study aims to improve the control of Tetranychus urticae on edible crops in greenhouses by introducing a guild of predators, each ecologically adapted to a particular niche in the life cycle of the pest or the crop cycle of the host-plant. The activity and predatory behaviour of two predatory mite species (Phytoseiulus persimilis and Amblyseius californicus) were studied to determine the effects of environmental aspects such as humidity and temperature levels in the presence of the prey T. urticae on tomatoes, aubergines, cucumbers and peppers. Host-plant species strongly influenced the performance of the predators with both species being most active on pepper, and least active on aubergines. When tested at three different humidity levels (30%, 65% and 90% r.h.) performance measures of P. persimilis such as distance covered, turning rate and speed of movement peaked at high relative humidity and high temperature levels. In contrast A. californicus preferred low humidity levels and high temperature levels. Furthermore it was observed, that A. californicus could survive longer periods on low prey density.

    5. Page 392
      Abstract

      Many species of Pinus of Northern Hemisphere origin have been introduced into Brazil, and are now grown extensively due to their importance to the timber industry and as ornamentals. Almost all of these introductions were done through seeds, but seedlings of some species were brought by immigrants, for example, Pinus pinea L., brought into Southern Brazil by Italians. Eriophyid mites identified as Platyphytoptus pineae Castagnoli, 1973, a species described from P. pinea in Italy, were collected from needles of Pinus oocarpa Schiede, in Brasília, Central Brazil. Hypotheses as to how this mite was introduced into Brazil are presented. The need for quarantine measures to avoid the introduction of other eriophyoid species associated with Pinus into Brazil are emphasized.

    6. Page 394
      Abstract

      The mite Microdispus lambi (Krczal) is phoretic on various species of Diptera associated with cultivated mushrooms in eastern Australia. The phoretic stage is the mated adult female. While the mite will attach to almost anything that moves, in a mixed population of adult Diptera, the preferred host is the phorid Megaselia halterata. M. lambi can be found attached to female M. halterata invading recently established mushroom crops on commercial farms. After several generations, M lambi swarm onto the surface of the mushroom beds at the same time as adult phorids are also emerging from the same beds. The phorids mate and disperse to newly established crops, starting start the next generation of phorids and mites.

    7. Page 399
      Abstract

      We suspected organophosphate (OP) resistance in T. urticae from cotton in Australia may confer cross-resistance to aldicarb. However, there was no accurate method available to test aldicarb that was compatible with our standard method using a Potter spray tower. We report a laboratory-based method to detect aldicarb resistance in T. urticae, using technical grade aldicarb dissolved in acetone, mixed with water and sprayed through a Potter spray tower. The spray tower is housed in an efficient down draft extraction cabinet. The method proved sufficiently sensitive to detect small differences in level of response and was useful for detecting and monitoring aldicarb resistance. Base-line data produced for T. urticae indicate a concentration of 0.5 g ai aldicarb / L should be used to discriminate resistance. Cross-resistance to aldicarb from OP resistance in T. urticae from cotton was not detected. Aldicarb has been used for several years in Australian cotton to control thrips and also gives early season control of T. urticae. Our data indicate that this practice is currently effective for T. urticae control and is likely to remain so unless there is a significant change in use patterns.

    8. Page 403
      Abstract

      A survey of the Banks grass mite, a pest of date palms in California, showed that adults and eggs occurred throughout the year on date fronds. On fruit bunches, mite numbers were highest in July (mid-summer) when the fruit was immature and susceptible to feeding damage. Mite densities on bunches were highly variable within trees. Predatory mites also were found on fronds throughout the year but only sporadically in January (late winter) and March (spring). No predatory mites were found on bunches until June. Bunches receiving commercial applications of sulfur sustained date mite numbers five times higher than in non-treated trees. Sulfur treatment suppressed numbers of predatory mites, which could have contributed to the increase in date mite numbers. Non-treated trees had a higher proportion of lightly infested bunches than did treated trees, while treated trees had more bunches that were heavily infested.

    9. Page 409
      Abstract

      Scolothrips indicus Priesner was found in spider mite colonies on eggplant in Taiwan. Its life cycle, food consumption, and seasonal fluctuations were studied to understand its impact on spider mite populations. S. indicus was reared in an incubator at 28 C with a photoperiod of 13: 11 (L: D), and fed eggs of Tetranychus kanzawai Kishida. The egg, larva 1, larva 2, prepupal, and pupal stages of S. indicus lasted 5.0, 2.0, 2.0, 1.0, and 1.1 days, respectively, with a total developmental time of 11.1 days. The two larval stages consumed 9.1 and 29.7 spider mite eggs, respectively. Adult females lived 11 days on average, and laid 22.8 eggs. Daily fecundity peaked on the 4th day after eclosion, and 60% of eggs were laid in the first 6 days. In their lifetimes, on average, adult females consumed 650.2 spider mite eggs, with a daily consumption of 56.5 spider mite eggs. This thrips consumed approximately 30 spider mite eggs to produce one egg of her own. Surveys conducted in eggplant fields showed that the population of this thrips fluctuated following changes in the spider mite population. A decrease in the spider mite population affected this thrips’ population more than precipitation did in the surveyed year. In the field, this thrips occurred mostly on leaves containing a few hundred spider mites. This may provide information on the distribution of S. indicus in relation to spider mite populations.

    10. Page 413
      Abstract

      To explain the sporadic appearance of Lorryia formosa Cooreman (Acari: Tydeidae) on grapefruit and its consistent presence in orange agroecosystems of northeastern Mexico, an experimental study was designed in which field-collected mites from orange and grapefruit were reared on respective leaf substrates under laboratory conditions. Developmental stages and life table parameters for this mite on both host leaves were estimated. The results indicated that on orange, the immature and adult stages of this mite developed 15 and 20% faster respectively, compared with grapefruit. The population of this mite on orange increased almost 43% per generation, had a positive rm and required a period of 89.2 days to double its abundance. On grapefruit, the L. formosa population declined by about 45% per generation, and it had a negative rm indicating that its population reduces to one half within 54.4 days. Adult females made up 70% of the population on orange compared with only 38% on grapefruit. These data indicate that a L. formosa population is capable of surviving and reproducing on both of these plants, but its population increases only on orange. We conclude that L. formosa is probably a casual visitor to grapefruit and a resident of orange.

    11. Page 419
      Abstract

      Collection of mites from jujube in Thailand revealed the occurrence of at least 16 species of mites belonging to seven families. Among these nine species were regarded as pests and the rest were regarded as predators. The most important and dominant species of phytophagous mites was the African red mite, Eutetranychus africanus (Tucker), while the most common predator was Phytoseius hongkongensis (Swirski and Shechter). The gall forming mite Aceria ghanii Keifer was recorded in Thailand for the first time. There was no difference in the abundance and diversity of mites on jujube in IPM and conventional plots. The density of mite pests, mainly spider mites, was normally low while that of the phytoseiid predators was generally abundant, almost throughout the investigation. A sudden increase in the population of spider mites was observed in December and January. There was only a slight fluctuation in the population of phytoseiid predators, which indicated their ability to survive on other alternate food sources during the absences of mite pests of jujube in the orchard.

    12. Page 423
      Abstract

      Interactions between larvae of the green lace wing Chrysoperla carnea and the spider mite Tetranychus neocaledonicus were observed on okra at various predator:prey ratios. In the laboratory, these were 1:25, 1:50, 1:100, 1:200, 1:500. In field trials 25,000, 50,000 and 100,000 C. carnea were released in a field at main research station, University of Agricultural Sciences, Dharwad. At 1:25 and 1:50 ratios in the laboratory, the predator eliminated the prey completely. At 1:100,1:200 and 1:500 ratios the prey mite maintained populations even 13 days after release of the predators. C. carnea failed to cope with the prey due to the high density of female mites which continued to lay eggs. In the field the predator released at the highest dosage of 100,000 larvae ha−1 proved as effective as dicofol 0.04% spray and was superior to predator doses at 25,000 and 50,000 larvae ha−1.

    1. Page 429
      Abstract

      There are three apple producing regions in the south western area of South Africa. These are around Elgin, Ceres and in the Langkloof centered around Joubertina. The spider mites, Tetranychus urticae Koch and Panonychus ulmi (Koch), are found in the Elgin area while only T. urticae causes damage in the Ceres area and the Langkloof. A variety of indigenous predatory mites, mainly phytoseiids, and two predatory beetles have been found. However, their contribution to biological control of these two spider mites is negligible. During 1989 Galendromus occidentalis (Nesbitt) was imported and released in the Ceres and Elgin areas. It established in the former but not in the latter; however, biological control achieved by this predator in the Ceres area was disappointing. Phytoseiulus persimilis Athias-Henriot appeared in apple orchards during 1989 and was distributed for biological control during 1990. However, successful biological control was erratic and largely dependent on the presence of certain weeds in the cover crop. To counter this, experimental importations and releases from a European insectary were conducted. These were not successful. During 1994 Neoseiulus californicus (McGregor) was recorded in apple orchards. It was very widespread and has resulted in a marked reduction in miticide sprays. In addition, no adverse effects on the local predators have been detected.

    2. Page 436
      Abstract

      This paper reviews and compares mite control programs in Australian horticulture that use exotic and native phytoseiids. Three relatively prey-specific phytoseiid species, Galendromus occidentalis (Nesbitt) (two pesticide-resistant strains), Typhlodromus pyri Scheuten and Neoseiulus fallacis (Garman) were introduced into Australia in the 1970s for control of twospotted spider mite (TSM), Tetranychus urticae Koch, or European red mite, Panonychus ulmi (Koch), on apples and other deciduous fruit. In addition, the renowned TSM predator, Phytoseiulus persimilis Athias-Henriot, appeared in Australia for the first time in 1978. All four species successfully established and three (G. occidentalis, T. pyri, P. persimilis) became important components of integrated mite control programs in a number of horticultural crops. The success of G. occidentalis and T. pyri in deciduous orchards continues to be closely linked to their tolerance of some pesticides. They are rarely found outside crop ecosystems. There is no evidence to suggest that these introduced phytoseiids have invaded native habitats or have led to imbalances in the native phytoseiid fauna. In southern New South Wales development of low pesticide input programs in stone fruit have led to a native phytoseiid, Euseius victoriensis Womersley, displacing G. occidentalis in the control of TSM. Recent research has shown that native phytoseiids readily colonise horticultural crops with low pesticide inputs such as citrus, grapes and lychees, and that they provide good control of pest mites. Furthermore, most native phytoseiids found in crops appear to be generalist feeders, maintaining populations in the absence of mite prey and therefore removing the need for close monitoring of pest and predator populations. Seven native or endemic phytoseiids (E. victoriensis, Typhlodromus doreenae Schicha, Amblyseius herbicolus (Chant), Amblyseius lentiginosus Denmark and Schicha, Euseius elinae Schicha, Typhlodromus dossei Schicha, Phytoseius fotheringhamiae Denmark and Schicha) are utilised in current biological control programs in Australian horticulture. G. occidentalis, T. pyri and P. persimilis continue to play an important role in mite control, particularly in pesticide-driven and therefore closely monitored crops like apples and strawberries. However, it is likely that native phytoseiids will play an increasingly important role in mite control in Australian horticulture as pesticide inputs lessen and crop ecosystems become more contiguous with natural ecosystems.

    3. Page 444
      Abstract

      The lucerne flea, Sminthurus viridis, is a serious pest of clover in dairy pastures in northern Tasmania. Studies on an established complex of European predatory mites were carried out in the state between 1976–80. The most important of these predators were the bdellid, Bdellodes lapidaria, the parasitids, Pergamasus longicornis and P. quisquiliarum and the anystid, Anystis baccarum. However, there was no evidence that any of these species, either singly or in combination, were able to exert significant control. Neomolgus capillatus was successfully established in Tasmania as an additional predator of S. viridis following introductions from the homoclimatic area of the Brittany region of northwest France. The introduction of N. capillatus into the predator complex reduced the density of S. viridis by ca. 85% in both autumn and spring. However, S. viridis activity begins in early spring when activity of N. capillatus is low so S. viridis is able to reach damaging population levels later during spring, despite later high predation levels. In contrast, N. capillatus activity precedes S. viridis in autumn and the naturally lower autumn populations are controlled to non-damaging levels. N. capillatus spreads very slowly (ca. 75m/year under favourable conditions). This restricts its effectiveness as a short term control measure. However, redistribution programmes have now resulted in the collection and transfer of around 1.6 million predators to over 800 sites in northern Tasmania. Surveys have shown that N. capillatus can be expected to establish at 90% of the release sites which now includes most dairy farms where S. viridis limits production. In the future, landholders will need to be encouraged to redistribute N. capillatus from established sites within their properties and to adopt biological control as part of an integrated control strategy to control spring populations. The possible benefits and disadvantages of using an additional predator, Anystis wallacei, to assist control of spring populations of S. viridis are also considered.

    4. Page 453
      Abstract

      The first mite species used for biological control of a weed was Tetranychus desertorum (= T. opuntiae) against prickly pear in the 1920s and, although an accidental introduction, it demonstrated several of the properties that can make an agent successful: a high degree of host-specificity, easy establishment, rapid population buildup, and rapid dispersal. Deliberate introductions of mites for biological weed control, however, began only in the 1970s. There has now been sufficient work to take stock of the successes and failures and to re-evaluate the potential of mites to control weed infestations. Mites have a variety of life-history strategies, such as gall-forming, cell-sucking and leaf-mining, and can act as vectors of plant diseases. This paper examines the usefulness of these different strategies for weed control, using selected case studies. Mite life-history attributes that favour successful biological control are discussed, and cases where the potential for control has not been realised are evaluated. Although no major weed control success has yet been attributable to mites, they have in many cases made important contributions to overall weed management. Given the large numbers of phytophagous mite species associated with plants that have become weedy in introduced ranges, they provide a promising pool of candidate agents for future control projects.

    5. Page 464
      Abstract

      Advances have been made in understanding the mechanisms behind the current geographical distribution and recent colonisation of Euseius Wainstein spp. on citrus in southern Africa. Three widely distributed species occur within three distinct latitudinal ranges. E. addoensis (van der Merwe & Ryke) occurs between 29 and 35°S, E. citri (van der Merwe & Ryke) between 22 and 29°S and E. pafuriensis (van der Merwe) between 17 and 23°S. Attempts to establish E. pafuriensis within the middle of the range occupied by E. citri failed due to the inability of E. pafuriensis to overwinter. Experiments showed that E. pafuriensis entered diapause in short day-length conditions combined with low temperature, whereas E. citri did not. Other Euseius spp. have restricted distributions in specific habitats. E. tutsi (Pritchard & Baker) occurs at altitudes above 1,000 m in South Africa and above 1,400 m in Zimbabwe, within areas that are otherwise occupied by the three widely distributed species mentioned above. E. transvaalensis (van der Merwe & Ryke) has only been found on citrus in habitats where mist or drizzle is common in winter. E. orygmus (Ueckermann & Loots) has only been found on citrus north of 20°S in orchards where few pesticides are sprayed. Differences between species in their susceptibility to pesticides used in citrus has allowed E. citri to displace E. tutsi at lower altitudes and to move into the latitudinal range of E. pafuriensis. Morphological differences between species are greatest when comparing E. tutsi and E. transvaalensis with E. pafuriensis and E. rhusi (van der Merwe). Most dorsal setae on the latter two species are extremely short whereas all dorsal setae on the former two species are long. As the regions where E. pafuriensis (and to a lesser extent E. rhusi) occurs are mostly at low altitude with warm winters and hot summers, it is possible that the average dorsal setal length is associated with thermoregulation.

    6. Page 470
      Abstract

      The biology of Amblyseius coccosocius Ghai and Menon, an important predator of tea red spider mite in India, was examined in the laboratory. Rearing at four constant temperatures, viz. 20, 25, 30, 35°C indicated that developmental period increased with decreasing temperature, while daily rate of egg laying, fecundity and longevity (both female and male) were highest at 25°C and lowest at 35°C. Considering the relatively shorter developmental period, higher fecundity, low mortality and maximum longevity, 25°C was found to be the most suitable for development of A. coccosocius while 35°C was least suitable.

    7. Page 473
      Abstract

      Despite much interest in using mites for the biological control of pests, little is known about the overall pattern of research conducted on these natural enemies (with the exception of the Phytoseiidae). Two major data-banks, AGRICOLA (from 1970) and CAB Abstracts (from 1984), were searched for references to 11 families meeting the following prerequistes: (1) at least one member had been used in biocontrol; (2) at least 40 references were available and (3) they did not consist mainly of pests. Due to the structure of the databanks, the entire period had to be divided into three parts: 1970–1984, 1984–1991 and 1991–1997. A total of 3904 references to these families were obtained. Publication rate increased steadily during the three periods; ca 650 papers were added from interval to interval and half were published during the last seven years. Publications on the Phytoseiidae dominated the literature, with a consistent >50% majority during all periods. Another analysis was limited to the eight families about which 99 or more papers were published. The Ascidae, Laelapidae, Phytoseiidae and Stigmaeidae together accounted for almost 80% of all papers and showed similar growth. Research on other families was uneven. Interest in the Macrochelidae levelled off, whereas studies on the Pyemotidae declined. This analysis reflects the current pattern of research on mites as biocontrol agents and indicates trends of an important component of pest control.

    8. Page 476
      Abstract

      Interest in phytoseiid mites in Australia began in 1954 when Womersley described 12 native species. In 1966 a cooperative effort between Federal and State agencies was launched to develop a pest management program in pome fruit. During the 1960s, Readshaw collected 15 species of predatory mites from apple orchards across the country and identified those with most potential for the control of phytophagous mites. In the 1970s he oversaw the importation and release of insecticide-resistant strains of Galendromus occidentalis (Nesbitt), Typhlodromus pyri Scheuten and Neoseiulus fallacis (Garman). The success of this program sparked interest in other applications of phytoseiids in biological control programs. Phytoseiulus persimilis Athias-Henriot was discovered in strawberries in New South Wales in 1978, and commercial development for application in strawberries, nurseries and protected crops followed. Only P. persimilis and G. occidentalis are currently mass-reared by commercial insectaries in Australia. Australia has a wealth of phytoseiid species. Schicha described over 90 species from Australia, but many more remain undescribed or undiscovered. Very little is known about the ecology of most of them. Those on which attention has so far focussed are associated with citrus, stone and pome fruit, grapevines, strawberries and protected crops. Apart from P. persimilis, manipulation of phytoseiids in Australia has been largely confined to classical biological control programs of release and establishment in perennial tree crops, with the aim of creating a permanent population in the environment, and conservation of native species by careful selection of pesticides. There is scope for commercial exploitation and mass-release of indigenous phytoseiids in Australia, particularly in short term crops, to reduce the present heavy reliance on chemical pesticides. This paper reviews the past, present and future of phytoseiid exploitation in Australia.

    9. Page 484
      Abstract

      An analysis of data so far available from India reveals that mites belonging to the families Phytoseiidae, Cheyletidae, Stigmaeidae, Anystidae, Bdellidae, Erythraeidae, Tydeidae, Cunaxidae, and Ascidae; predatory insects belonging to the Thripidae, Staphylinidae, Anthocoridae, Lygaeidae, Coccinellidae, Hemerobiidae, and Chrysopidae; and fungi belonging to the genera Cladosporium, Neozygites and Hirsutella, are important natural enemies of phytophagous mites of India, and some of these have potential for keeping pest mite populations in check. Likewise some mites of the families Acaridae, Trombidiidae, Anystidae, Pyemotidae, Erythraeidae, Bdellidae, Phytoseiidae, Laelapidae, Uropodidae, Otopheidomenidae and a few Oribatida are known to feed on or parasitise important insect pests. Three species of Oribatida are known to feed upon nematode pests, while one species each of Oribatida and uropodid mites have been reported to attack molluscan pests. Finally, as many as nine species of mites are known to feed on noxious weeds, and some can effectively control them. All these are reviewed in this paper, citing the relevant references and giving, wherever possible, their food preference, feeding habits, feeding potentiality, etc. with a view to highlighting promising natural enemies for inclusion in biological control programs in India.

    10. Page 498
      Abstract

      Daily predation, oviposition and functional responses of Amblyseius ovalis foraging for different stages of Tetranychus urticae were studied on 2 × 2 cm2 polyethylene arenas. The predators foraging for eggs and larvae increased the daily predation rate faster with increasing prey densities, and reached higher plateaus than those feeding on later stages of T. urticae (Holling’s Type II functional responses). The coefficients of time required to produce an egg (b1) and handling time (Th) were estimated from the fitted regression equations by disk model. The daily reproductive rate of A. ovalis was decelerated with incremental prey densities. The maximum-daily reproduction and predation rates of female A. ovalis feeding on different prey stadia were respectively estimated from 1 / b1’s (egg = 1.71, larva = 2.07, nymph = 0.86, female = 1.36, and male = 0.53) and 1 / Th’s (egg = 12.82, larva = 15.15, nymph = 4.93, female = 4.37, and male = 0.97), which were used to evaluate the reproductive value of a prey (food-reproduction-exchange indices). Among all the tested prey stadia the female T. urticae gave the highest predator reproductive values, but the lowest predation rate. The size, activity and the webbing produced by the prey females were assumed to be major factors preventing predation.

    11. Page 506
      Abstract

      When foraging for eggs and females of Tetranychus urticae Koch on different substrates (polyethylene tile vs. lima bean leaf arenas), Amblyseius ovalis (Evans) demonstrated a Holling’s disk function in small arenas and a sigmoid function in larger arenas. When feeding on eggs or females and responding to density of T. urticae, A. ovalis showed a faster increasing rate of daily predation but a longer period to the plateaus on leaf arenas than on polyethylene tiles. A. ovalis foraging for females of T. urticae reached a predation plateau faster and showed a higher predation plateau than those foraging for eggs. The size of the rearing arena of polyethylene tiles accelerated the daily predation rate faster on smaller arenas than on larger ones, but both reached similar level of plateaus. The highest daily predation rates estimated by 1 / Th and b0, obtained from fitted disk and sigmoid regression equations respectively, were not significantly different between small and large arenas. We concluded that female A. ovalis spent most of the time handling prey, i.e. with a constant daily predation potential at high prey density. Searching time was negligible in the smaller testing units.

    12. Page 513
      Abstract

      Releases of the predatory mite, Amblyseius longispinosus (Evans) on strawberries in Thailand at rates of 2, 5 and 10 mites per plant at 2-week intervals gave good results in controlling the two-spotted spider mite, Tetranychus urticae Koch. Release rates of 2–5 mites per plant were both effective and economical. A study using A. longispinosus to control T. urticae in a strawberry greenhouse during heavy infestations showed that 7 releases at rates of 2–5 mites per plant at 2-week intervals gave good control of T. urticae within 12 weeks. The average inflorescences per plant were statistically different between predator release treatments and the control.

    13. Page 518
      Abstract

      The Chilean predatory mite Phytoseiulus persimilis Athias-Henriot is a well known introduced biocontrol agent that has become naturalised in agricultural fields in many areas of Australia. In a previous study, subtropical rainforest remnants of Queensland were shown to be resistant to invasion by P. persimilis. To determine if this resulted from environmental preferences of P. persimilis for open, sunny habitats, we performed two tests. In the first, we introduced the predators onto potted bean plants infested with their preferred prey (Tetranychus urticae C. L. Koch) 200 m into the rainforest and in fields at two sites (Redlands and Mt Glorious) and followed population densities of both prey and predator for two weeks. We found no difference in the mean numbers of predators between fields and rainforest. In a second experiment in a glasshouse, where the predator was given a choice between shaded and unshaded bean plants, predators preferred shaded plants. Thus, when its prey are present, P. persimilis appears to be able to exploit the rainforest habitat.

    14. Page 522
      Abstract

      In the present work we examine the distribution of phytoseiid mites in two different environments in Sicily: natural ecosystems (forests and mediterranean maquis) and agroecosystems. In the latter the plants sampled were spontaneous and cultivated. Consequently we compared phytoseiid species present in the following three groups of plants: (1) spontaneous plants in natural ecosystems, (2) spontaneous plants in agroecosystems and (3) cultivated plants in agroecosystems. For each group, herbaceous, shrubby and arboreal plants were considered. We measured the similarity between the phytoseiid faunas of these three types of plants. In natural ecosystems, we found 32 species of phytoseiid mites on arboreal plants, 14 on shrubby plants and 15 on herbaceous plants. In agricultural ecosystems, we found nine species of phytoseiids on arboreal spontaneous plants, 21 on shrubby plants, and 19 on herbaceous plants. Finally, 25 species were collected on cultivated arboreal plants, 21 on shrubby, and seven on herbaceous plants. The similarity (Sorensen index) was highest between cultivated shrubby and spontaneous shrubby plants in agricultural ecosystems (0.71). A high similarity of 0.60 was also found between these two groups and the arboreal cultivated and arboreal spontaneous plants in natural ecosystems. We conclude that in Sicilian environments, great importance should be given to spontaneous plants for the conservation of the indigenous phytoseiid fauna.

    15. Page 530
      Abstract

      We surveyed the phytoseiid mites of citrus, apple, lychee and rice in China. Totals of 31, 18, 15, 11 species occured on these crops respectively. A list of the species occurring on each crop is given. Several of these species have been shown to be of value in controlling phytophagous mite pests.

    1. Page 535
      Abstract

      Mites and ticks continue to be of medical and public health concern in Australia. Trombiculid mites are responsible for scrub itch and occasional cases of scrub typhus in northern Australia, and there has been a recent fatality. Scabies continues to be a community problem, misdiagnosis is an issue and permethrin resistance has been reported. Localities in eastern Australia have relatively high population densities of dust mites, which produce respiratory and dermatologic complaints. Bird, rodent and plant mites cause seasonal discomfort. Infestations with stored product mites are less common than previously, although one exotic species causing severe irritation in produce handlers has been detected recently. Delusionary parasitosis is a difficult issue, involving considerations of mite infestation and/or neurosis. Ixodid ticks are responsible for allergic reactions which are sometimes severe in humans, and a few species can cause an ascending flaccid paralysis in children. Ixodes-borne rickettsiae cause spotted fever infections along the eastern seaboard, and Lyme disease has been reported but its status is controversial. Viruses have been associated with ixodid and argasid ticks of sea-birds on off-shore islands. Exotic tick species have been introduced to Australia, and travellers infected with African tick typhus have been detected in Australia.

    2. Page 547
      Abstract

      Tick-borne zoonoses in Europe include Lyme borreliosis (LB), tick-borne encephalitis (TBE), babesiosis, ehrlichiosis, Q-fever and rickettsiosis. Some of these diseases, such as Q-fever and the spotted fever rickettsioses, have been known for many decades and have attracted little attention in recent times, although there are several unanswered questions concerning their ecology and epidemiology. On the other hand considerable recent attention has been paid to zoonotic diseases transmitted by the commonest ixodid tick species in Europe, Ixodes ricinus L. This topic came to the fore with the emergence of Lyme borreliosis (LB) in the early 1980s and the subsequent realisation that interaction between other concurrently transmitted pathogens, such as TBE virus and various species of Ehrlichia and Babesia, may be highly significant. The focality of some of these diseases differ significantly and the reasons are to be found in the behaviour of the pathogens in ticks and/or reservoir hosts. The transmission of several different pathogens by the same tick species may have implications for diagnosis, pathogenesis and epidemiology.

    3. Page 552
      Abstract

      This paper presents a current picture of scabies research and management and considers whether meaningful gains have been made into control of this disease in humans. A brief historical outline is followed by a summary of progress in studies of the taxonomy and anatomy, host response and immunity, diagnosis and clinical picture, and epidemiology. Although there is still some taxonomic uncertainty, most authors regard Sarcoptes scabiei as a single species with several varieties, according to host. Molecular means of determining varieties have been identified. Work is continuing on the internal morphology of the mite, and SEM studies have further elucidated aspects of Sarcoptes feeding and other behaviour. Recent studies of host response have identified key antigen presenting cells and components of cell-mediated immunity, and described other features of the host response. Some of this research might lead to a diagnostic test, which would be of considerable value. Diagnosis continues to be a problem, and poor diagnosis and untreated cases will contribute to the widespread occurrence of scabies, which has not significantly abated in most countries since the global rise in prevalence of the disease in the 1960s and 70s. Impoverished sectors of the community are still those at greatest risk of infestation, with indigenous groups in some countries being particularly affected, as well as those with HIV. Avermectin drugs are becoming more widespread in use and are helping control infestations where the traditional suite of treatments has proved ineffective. While not life-threatening, the disease can give rise to more serious sequels, and it is a chronic burden to public health authorities. Although a great deal of knowledge of scabies has accumulated over the years, the severely practical problems of its accurate diagnosis, swift and effective treatment, and control, remain significant challenges for which there appears to be no quick or easy answer.

    4. Page 558
      Abstract

      The predator dust mite, Cheyletus tenuipilis (Fain et al., 1980), was identified as part of the house dust mite fauna in Australia in 1994. It is well established that house dust mites, Dermatophagoides spp., are an important source of allergens which may trigger attacks of asthma and rhinitis. It might therefore be possible to utilise the predator properties of Cheyletus tenuipilis to control the numbers of the house dust mite Dermatophagoides pteronyssinus (Trouessart, 1897). In this study we prepared allergenic extracts from C. tenuipilis for skin prick testing and antibody staining. The results showed that C. tenuipilis is allergenic in some subjects who are sensitised to D. pteronyssinus. Therefore, the use of the predator C. tenuipilis to control domestic D. pteronyssinus numbers may not reduce potential allergen exposure for potentially susceptible individuals.

    5. Page 565
      Abstract

      The Asian honeybee, Apis cerana F., is the principal bee species employed in the apiculture industry in India. A recent survey of the mite fauna associated with Apis spp. in Kerala has yielded more than twenty species of mites belonging to four orders, including 15 new records. The type of association of the mites with bees has been determined through analysis of their distribution within the colonies and gut contents of the individuals. Ectoparasitism, brood parasitism, cleptoparasitism, phoresy and saprophagy are the types of association detected between mites and bees. Among the mites collected, a tarsonemid species, Pseudacarapis indoapis Lindquist represents the most widely distributed species throughout the state.

    6. Page 569
      Abstract

      The infection of oribatid mites by cestodes was examined at three farm sites in Kerala, India. Naturally infected mites were found in 5 of the 60 species of mites encountered, namely Galumna flabellifera orientalis Aoki, 1965, Scheloribates praeincisus var. interruptus Berlese, 1916, Ischeloribates lanceolatus Aoki, 1984, Pergalumna intermedia and a new species of Plakoribates. Various developmental stages of Moniezia sp., egg, onchosphere, spherical larva and cysticercoid were found in the mites’ bodies. The percentage infection among vector species ranged between 1.2 and 4.3. S. praeincisus var. interruptus recorded the highest rate of infection whereas Plakoribates sp. nov. showed the lowest. G. flabellifera orientalis was the only species found infected at all three sites. S. praeincisus var. interruptus exhibited cestode infection at two sites, while the remaining three species were infected at one site each. G. flabellifera orientalis and S. praeincisus var. interruptus appeared more prone to Moniezia infection and hence members of Galumnidae and Scheloribatidae emerged as potential agents in the transmission of monieziasis. This warrants augmentation of control measures of oribatid vectors. Furthermore, detection of nematode parasites in these mites suggests scope for future studies on the control of these vectors.

    7. Page 576
      Abstract

      Two different types of poultry houses (conventional and trampoline rearing system) in Lower Saxony, Germany were investigated in order to determine how the drying of the litter in the trampoline system affects the acarofauna. The acarid mite Sancassania berlesei occurred in both systems. In the conventional system, S. berlesei was dominant (99.8%) and reached a maximum density of about 2000 mites/g of litter. The abundance of S. berlesei depended on the substrate humidity. Due to the reduced humidity in the litter in the trampoline system, the abundance of this mite in this system was 800 times less than in a conventional one. In each chicken rearing period (about six weeks) in the conventional system, a distinct change was observed in the population of this mite. Two weeks after the beginning of each breeding period the mite population increased rapidly, and then decreased suddenly after another three weeks.

    8. Page 583
      Abstract

      The present study reports on the ectoparasitic mites found on Heteromys gaumeri Alen and Chapman, 1897 from Yucatan, Mexico. The following mites were identified: Steptolaelaps heteromys Furman, 1955 Androlaelaps (Haemolaelaps) fahrenholzi (Berlese, 1911), Hirstionyssus sp., Macrocheles sp., Ixodes sp., Amblyomma sp., Dermacentor sp., Pseudoschoengastia scitula Brennan and Jones, 1959, Euschoengastoides sp., Geomylichus (Ageomylichus) mexicanus Fain, 1976 one unidentified species of Trombiculidae, and one of the Acaridae. The most common mites were Steptolaelaps heteromys and Ixodes sp. The presence of Hirstionyssus sp. Dermacentor sp., Euschoengastoides sp., and Geomylichus (Ageomylichus) mexicanus are recorded for first time on this host.

    9. Page 586
      Abstract

      Five nests of Neotoma albigula were collected in Durango, México and the mite fauna examined. A total of 7,427 arthropods was collected, of which 5,086 were mites, representing at least 89 species and 59 families. The mites were analysed in terms of their ecology and distribution in the nests. Some species and families were found associated with nests of N. albigula for the first time.

    1. Page 597
      Abstract

      Unfed starving nymphs I, nymphs II, females and males of Argas reflexus (F.) were maintained at ambient temperature and humidity inside an experimental attic, a study site similar to the tick’s natural habitat. To determine whether A. reflexus is able to maintain its water balance at that site and whether active absorption of water vapour (WVA) occurs, tick body mass was monitored at 5 to 8-week intervals over a 14-month period. Tick body mass losses varied seasonally between ≈0% and 0.7%/day, confirming the high water retention capacity of A. reflexus. Tick mass losses correlated well with the seasonal pattern of water vapour saturation deficit. However, the relatively high mortalities of between 20% and 70% of the ticks indicate that the maintenance conditions (single ticks in glass vials) were not optimal for A. reflexus and that rates of mass loss are probably lower under natural conditions. Mean water contents of ≤65% in surviving ticks show that A. reflexus had experienced a certain degree of dehydration at the end of summer. Net gains in tick body mass, indicative of water vapour absorption, were only observed in autumn/winter, suggesting that unfed A. reflexus have a higher water content during overwintering than during the remainder of the year. Periods of >75% RH, the threshold for WVA in A. reflexus, coincided with comparatively low temperatures inside the attic. Thus, net gains through WVA were predominantly achieved at temperatures below 10°C.

    2. Page 604
      Abstract

      Insect and crustacean endocrinological studies have significantly advanced our understanding of the hormonal regulation of molting, metamorphosis and reproduction in the Mandibulata. Juvenile hormone (JH) in insects serves as a ‘status quo’ hormone. An increase in ecdysteroid levels in the presence of JH initiates a larval-larval molt, and ecdysteroids in the absence of JH results in metamorphosis to the adult. Juvenile hormone so far has only been found in the Insecta. Methyl farnesoate (the immediate biosynthetic precursor to JH) accelerates the action of ecdysteroids, promotes molting and reduces the duration of the intermolt period, and may have ‘status quo’ activity in the Crustacea. In insects and Crustacea, juvenile hormone and methyl farnesoate, respectively, appear to control vitellogenesis and egg maturation. In comparison to insects and Crustacea, our understanding of the endocrinology of ticks is minimal. Ticks most likely produce ecdysteroids from the epidermis under control of the synganglion, and these ecdysteroids regulate molting and have some role in egg maturation. No specific functions have been assigned to neuroendocrine organs in ticks like the retrocerebral organ complex or the lateral segmental organs. A critical re-examination of the endocrinology literature on ticks does not strongly support the presence of JH in ticks or a role for JH in tick metamorphosis or reproduction. For example, no clear evidence is available that the exogenous application of JH or JH analogs elicits delayed nymphal development or supernumerary molts in ticks; juvenile hormone and JH analogs failed to rescue anti-JH (precocene and fluoromevalonate) effects on metamorphosis and reproduction; and JH and JH analogs do not induce vitellogenesis. A few exceptions to these findings are discussed. Attempts to directly detect JH and its biosynthetic precursors in ticks by radiometric JH biosynthesis studies, JH Tenebrio and Galleria bioassays and ion selective EI GC/MS have also been unsuccessful. Considering that the sister group to the Insecta, the Crustacea, do not have juvenile hormone, the hypothesis that ticks have JH and use JH in the same manner as insects seems less likely today than previously thought. Further studies are needed to understand the role of ecdysteroids and identify other hormones that regulate tick molting, metamorphosis and reproduction.

    3. Page 612
      Abstract

      Synthesis of the insect juvenile hormone (JH) homologues and their precursors and the measurement of JH titer were investigated in two tick species, Dermacentor variablis and Ornithodoros parkeri. No JHI, JHII, JHIII, JHIII bisepoxide, methyl farnesoate or farnesol was synthesised in vitro from [methyl-3H]-methionine and farnesoic acid or from [1-14C]-acetate by synganglion, salivary gland, gut, ovary, fat body or muscle from multiple developmental stages and/or in larvae and adults. The same results were obtained with backless ticks incubated with JH precursors in vitro and when [methyl-3H]-methionine was injected into ticks. Diploptera punctata, Grom-phadorhina portentosa or Periplaneta americana were used as positive controls in these experiments and produced farnesol, methyl farnesoate and/or JHIII. No juvenilising activity was found in lipid extracts from eggs, larvae, nymphs or adults of D. variabilis using the Galleria pupal cuticle bioassay. Lipid extracts from D. punctata and 100pg of JHIII were positive controls in these experiments. No JHI, JHII, JHIII, JHIII bisepoxide, methyl farnesoate or farnesol was detected in hemolymph extracts from blood fed, virgin and replete D. variabilis or blood fed O. parkeri females analyzed by selective ion, electron impact, gas chromatograpy-mass spectrometry (EI GC-MS). The same technique was used for the accurate measurement of JH from hemolymph of D. punctata as a positive control. In our investigations of D. variabilis and/or O. parkeri, we detected no synthesis of the common insect juvenile hormones or precursors, none of the aforementioned juvenoids in tick hemolymph by EI GC-MS, nor juvenilising activity associated with tick extracts using the Galleria bioassay.

    4. Page 618
      Abstract

      Three abundant immunoglobulin G binding proteins (IGBPs) of 29 kD (IGBPMA), 25 kD (IGBPMB), and 21 kD (IGBPMC) were isolated from partly fed male Rhipicephalus appendiculatus ticks using an agarose-IgG column. Sequencing analyses showed that IGBPMB and -MC are related proteins. Both IGBPMB and -MC are glycosylated. IGBPMC is a secreted protein whereas IGBPMB does not have a signal sequence. Using immunoblotting, each of the three IGBPs was shown to be antigenically distinct. The distinction of IGBPMB and -MC antigenicities suggests that ticks may ‘hide’ the antigenicity of the unsecreted protein from their host to avoid being targeted by the host’s immune response. The protein profile of IGBPMA in male R. appendiculatus changed when the ticks stopped feeding whereas the profiles of IGBPMB and -MC remained unchanged. Detection of a precursor protein of IGBPMA indicates that male ticks modify salivary gland protein production according to their feeding needs. The mechanism of such post-translation protein modification that releases the functional form of IGBPMA is unknown, but probably involves a salivary gland derived protease.

    5. Page 622
      Abstract

      PAGE analysis of vitellogenin (Vg) in the soft ticks, Ornithodoros moubata and O. parkeri revealed the presence of two Vg components (Vg-1 and Vg-2) in both species. Both components react with anti-vitellin serum. Vitellin (Vn) and Vg-2 were homogenous as judged by PAGE, electron microscopy and immunodiffusion. Electron micrographs and molecular weights (600 kDa for Vn and Vg-2, 300 kDa for Vg-1) suggest Vn and Vg-2 are dimers of Vg-1. Six or seven polypeptides for Vgs and six or seven polypeptides for Vn were demonstrated by SDS-PAGE. The total molecular weight of these multiple polypeptides was greater than that of the end products. This discrepancy is likely a result of uncleaved intermediate products of proteolysis. Vitellogenin proteins are synthesised in the fat body, carried to the ovary by the hemolymph, processed to Vn by proteolysis, then incorporated into the oocytes. Vitellogenesis is most commonly induced by a blood meal. Ligation experiments showed that two factors are required to stimulate the production of Vg in the fat body. The first factor was shown to be a peptide produced by the synganglion and named vitellogenesis-inducing factor (VIF). This factor stimulates a tissue in the posterior half to produce a second factor, fat body stimulating factor (FSF), to stimulate the fat body to produce Vg. It is speculated that this second factor is a steroid. Injection of ecdysteroids stimulated low levels of Vg production in unfed females. Ecdysteroid titers in the hemolymph showed two peaks, one coinciding with the release of FSF and a second larger peak that coincided with oviposition.

    6. Page 628
      Abstract

      A specific prostaglandin E2 (PGE2) receptor has been identified in the salivary glands of female lone star ticks, Amblyomma americanum (L.). The receptor is linked to a guanine nucleotide (G) protein and activates a phosphoinositide phospholipase C signalling pathway increasing the inositol trisphosphate level and mobilising intracellular Ca2+. Low concentrations of PGE2 stimulate secretion of anticoagulant proteins by dispersed salivary gland acini. We hypothesise that, after the initial stimulation of salivary glands by dopamine, the PGE2 formed mobilises Ca2+ and results in the secretion (exocytosis) of bioactive proteins into the saliva during tick feeding.

    7. Page 634
      Abstract

      Previous studies suggested that Lone Star Ticks (LST), Amblyomma americanum, are not evenly distributed in nature, but are instead clumped or clustered in areas frequented by their vertebrate hosts. Results of two studies are presented here: (1) a project to carefully document LST clustering in relation to shade and soil moisture, and (2) a pilot project to evaluate the effectiveness of acaricidal spot treatment of clustering sites. In both studies, trails were marked through the woods and drag-cloth tick collections were made (every 10 metres) weekly to assess spatial distribution patterns and relative abundance. The first study showed clear patterns of lone star tick clustering, especially of nymphs, in association with shade and soil moisture. Ticks were only collected in areas with >23% soil moisture. Only three ticks out of 221 were collected in 10% or less shade. The average percent shade for areas where all adult LST’s were caught was 63% in lane one and 43% in lane two. The second study constituted an attempt to identify spots of LST clustering along nature trails in a Mississippi State Park and to spot treat those areas with deltamethrin, a pyrethroid insecticide. Spot treatment provided tick control of 72.7–100% for two months (with two exceptions). For the entire first month after spraying there was an average 88.1% control.

    8. Page 638
      Abstract

      Fed female ticks, Dermacentor variabilis, survived for at least 5 days without significant mortality following intrahemocoelic inoculation of the bacterial species Bacillus subtilis, Staphylococcus aureus, Micrococcus luteus, Escherichia coli, and Borrelia burgdorferi. In contrast, survival of ticks 5 days after inoculation with Pseudomonas aeruginosa was only 12% and the few surviving individuals appeared moribund. However, survival of ticks inoculated with heat-killed P. aerurginosa was 100%, suggesting that lethality of this bacterial species required viable cells. D. variabilis was found to control E. coli, a representative gram negative bacterium, very rapidly. Some control was evident in as little as 1 hour after bacterial inoculation, and all E. coli cells were cleared from the hemolymph within 6 hours. This is a much more rapid response than that previously observed for B. subtilis. D. variabilis hemolymph plasma from E. coli-challenged ticks inhibited microbial growth, but hemolymph from non-challenged ticks did not inhibit growth of E. coli. This differs from studies with ticks challenged with B. subtilis, which were found to be constitutively anti-microbial. Anti-E. coli activity of hemolymph plasma from challenged ticks was correlated with two relatively non-polar fractions separated by HPLC using a reversed phase Vydac (C4) protein column. However, these fractions had no effect on B. subtilis. Similarly, fractions separated by HPLC from B. subtilis-challenged ticks had no effect on E. coli growth. In addition to its activity against the non-vectored, non-pathogenic bacteria, D. variabils hemolymph from E. coli-stimulated ticks was also found to be borreliocidal against the Lyme disease spirochete, Borrelia burgdorferi. Further study is needed to purify and identify the antimicrobial proteins or peptides active in tick hemolymph against this array of different types of microbes.

    9. Page 645
      Abstract

      A study was undertaken to examine the ability of different individuals of a selected cattle breed to sustain Theileria parva parva infection and high tick infestation. This was done by determining piroplasm levels of T. p. parva in the blood of infected susceptible Bos taurus cattle. The life span of individual cattle infected with different strains of T. p. parva and the size of various Rhipicephalus appendiculatus tick populations to engorge on the infected cattle was assessed. Eight steers of European breed, (Bos taurus type), previously shown to be negative for antibodies against T. parva showed significant differences in their ability to sustain different T. p. parva strain infections. Significant differences in numbers of ticks which completed feeding were demonstrated in the different tick populations. However, no difference was recorded in the numbers of ticks which completed feeding on cattle infected with the different strains of the parasite.