A comprehensive molecular phylogeny of the terrestrial Parasitengona (Acariformes, Prostigmata) provides insights into the evolution of their metamorphosis, invasion into aquatic habitats and classification.

Parasitengona (velvet mites, chiggers and water mites) is a highly diverse and globally distributed mite lineage encompassing over 11,000 described species, inhabiting terrestrial, freshwater and marine habitats. Certain species, such as chiggers (Trombiculidae), have a great medical and veterinary importance as they feed on their vertebrate hosts and vector pathogens. Despite extensive previous research, the classification of Parasitengona is still contentious, particularly regarding the boundaries between superfamilies and families, exacerbated by the absence of a comprehensive phylogeny. The ontogeny of most Parasitengona is distinct by the presence of striking metamorphosis, with parasitic larvae being heteromorphic compared to the predatory free-living deutonymphs and adults. The enigmatic superfamily Allotanaupodoidea is an exception, with larvae and active post-larval stages being morphologically similar, suggesting that the absence of metamorphosis may be either an ancestral state or a secondary reversal. Furthermore, there is disagreement in the literature on whether Parasitengona had freshwater or terrestrial origin. Here, we inferred phylogenetic relationships of Parasitengona (89 species, 36 families) and 307 outgroups using five genes (7,838 nt aligned). This phylogeny suggests a terrestrial origin of Parasitengona and a secondary loss of metamorphosis in Allotanaoupodoidea. We recovered the superfamily Trombidioidea (Trombidioidea sensu lato) as a large, well-supported, higher-level clade including 10 sampled families. We propose a new classification for the terrestrial Parasitengona with three new major divisions (epifamilies) of the superfamily Trombidioidea: Trombelloidae (families Audyanidae, Trombellidae, Neotrombidiidae, Johnstonianidae, Chyzeriidae); Trombidioidae (Microtrombidiidae, Neothrombiidae, Achaemenothrombiidae, Trombidiidae, Podothrombiidae); and Trombiculoidae (=Trombiculidae sensu lato). Adding them to previously recognized superfamilies Allotanaupodoidea, Amphotrombioidea, Calyptostomatoidea, Erythraeoidea, Tanaupodoidae and Yurebilloidae.

Removing grass clippings reduces bermudagrass mite (Acari: Eriophyidae) infestation during turfgrass regrowth.

Bermudagrass mite (Aceria cynodoniensis Sayed) infestation stunts bermudagrass (Cynodon spp. [Poales: Poaceae]) growth, leading to thinned turf and lower aesthetic and recreational value. Bermudagrass mites cause characteristic symptoms called witch's brooms, including shortened internodes and leaves and the proliferation of tillers. Grass clippings produced by mowing or scalping bermudagrass harbor mites, which abandon the desiccating grass clippings and spread to surrounding turfgrass. Dropped grass clippings can lead to infestation of new turfgrass. Nursery experiments were conducted with potted bermudagrass to determine the effect of removing witch's brooms or grass clippings after scalping on witch's broom densities on the recovering bermudagrass. Additionally, laboratory experiments were conducted to assess the potential for mites to abandon detached witch's brooms and to evaluate mite survival after leaving their hosts. The number of initial witch's brooms and individually removing witch's brooms did not affect subsequent witch's broom densities, suggesting that infested but asymptomatic terminals later developed into witch's brooms. Removing grass clippings after scalping reduced witch's broom densities by over 65% in two trials. Most mites (96%) abandoned witch's brooms within 48 h after detaching witch's brooms, and adult mites survived an average of 5.6 h after removal from the host plant. Removing clippings after scalping may improve bermudagrass mite management and limit damage on the recovering turfgrass. Additionally, clippings resulting from regular mowing or scalping should be disposed of properly because this study demonstrates that mites abandon desiccating host plants and survive sufficiently long to infest surrounding turfgrass.

The impact of different photoperiod regimes on vital life traits of Amblyseius swirskii and Neoseiulus cucumeris (Acari: Phytoseiidae).

Environmental factors, such as photoperiod can play an important role in the development and performance of predatory mites. The influence of five photoperiod regimes (0: 24, 8: 16, 12: 12, 16: 8, and 24: 0 h; Light: Dark) on the population parameters of the predatory mites, Amblyseius swirskii Athias-Henriot and Neoseiulus cucumeris (Oudemans) was studied under the laboratory conditions at 25 °C and 25 ± 1 °C, 65 ± 5% RH. Regarding A. swirskii, the longest and shortest total pre-adult and total preoviposition periods (TPOP) were in the photoperiod of 12 L:12D and 16 L:8D, respectively. The oviposition days, adult longevity, total life span, fecundity, gross reproductive rate (GRR), and net reproductive rate (R0) of the predator had no significant difference in all photoperiods tested. The intrinsic rate of increase (r) and the finite rate of increase (λ) in 16 L:8D photoperiod had no significant difference with the other photoperiods tested except 12 L:12D. Regarding N. cucumeris, the shortest total pre-adult and TPOP were in full darkness. The oviposition days and fecundity were significantly higher in 16 L:8D than the others. The value of R0 in 16 L:8D was significantly higher than 8 L:16D. The highest values of the parameters r and λ were observed in full darkness, which had no significant difference with 16 L:8D and 24 L:0D. According to the results, the photoperiod regime had a more significant influence in terms of development and reproduction on N. cucumeris than A. swirskii, and 16:8 (L: D) h photoperiod was recognized as the proper regime for their rearing.

Exudate droplets incorporated on eggs by Raoiella indica Hirst female during oviposition may avoid the predation of Amblyseius largoensis (Muma).

Raoiella indica Hirst has rapidly and widely spread throughout the New World since 2004, primarily infesting coconut palms and interacting with the predator Amblyseius largoensis (Muma). Although A. largoensis feeds on R. indica at all stages of development, it cannot naturally reduce its population to levels that do not impact the host plant. Raoiella indica possesses dorsal setae that secrete exudates during all post-embryonic developmental stages, and females have a behavior that deliberately deposits droplets on the freshly laid egg, possibly as a defense strategy against predation in vulnerable stages. In this context, we analyzed whether the presence or absence of droplets in R. indica eggs affects predation using A. largoensis as a biological model. Thus, we evaluated whether some biological and behavioral characteristics of A. largoensis could be affected by the consumption of R. indica egg masses washed or unwashed with water. Also, we performed a chemical analysis of the droplets exuded by R. indica and provided a description of the oviposition behavior of R. indica. The predator showed a higher consumption rate and preference for washed eggs. The results suggest that the exudate droplets have defensive functions, which are incorporated by the female onto the egg during oviposition and subsequently during a patrolling behavior, as they lose their effect after being washed with water. Although the droplets do not prevent the predator from feeding, they reduce the number of R. indica eggs consumed without affecting the growth of A. largoensis.

Prey stage preference of Amblyseius paraaerialis (Acari: Phytoseiidae) on varied life stages of the spider mites Tetranychus urticae, Tetranychus macfarlanei and Oligonychus biharensis (Acari: Tetranychidae) and exploring the mass rearing possibilities of this predatory mite on alternative diets.

Spider mites Tetranychus urticae, Tetranychus macfarlanei and Oligonychus biharensis are considered to be highly polyphagous in nature and causes severe damage to a wide range of plants around the world. Amblyseius paraaerialis is an efficient phytoseiid predator of spider mites with a potential to survive on both natural and alternative diets. Evaluation of predatory potential and prey stage preference provides valuable information on the efficacy of the predatory species in controlling mite population. Feeding experiments were conducted on mulberry leaf discs under the laboratory conditions of 30 ± 2 °C and 70 ± 5% relative humidity (RH). After 24 h of feeding experiment, the adult female predator exhibited a significant preference in feeding towards the eggs of T. macfarlanei (42.6%) and the larval stages of T. urticae (46%) and O. biharensis (25.3%). The mass rearing possibilities of A. paraaerialis was tested by tracking and comparing the developmental duration of individual life stages on varied food sources like, honey, castor (Ricinus communis) pollen, honey-pollen mixture and mixed life stages of T. urticae. The predator was failed to complete its development on honey and pollen when supplied separately. However it was successfully developed on honey-pollen mixture and mixed life stages of T. urticae. The developmental studies unravelled a shortest developmental duration and an extended adult longevity and lifespan of A. paraaerialis when reared on the alternative diet, thus opened up the mass rearing possibility of the predatory species under laboratory conditions.

Life table parameters of Amblyseius largoensis, Amblyseius swirskii and Proprioseiopsis lenis (Acari: Phytoseiidae) fed on eggs and larvae of Frankliniella occidentalis.

The immature development and reproduction of the predatory mites Amblyseius largoensis (Muma), Proprioseiopsis lenis (Corpuz and Rimando), and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) were investigated using both thrips eggs and first instars of the western flower thrips, Frankliniella occidentalis Pergande, as prey in a controlled laboratory environment at 25 °C and 60% relative humidity. When provided with thrips eggs as food, A. largoensis exhibited a notably shorter immature development period for both males (7.05 days) and females (6.51 days) as compared with A. swirskii (8.05 and 7.19 days, respectively) and P. lenis (8.10 days and 7.05 days, respectively). Amblyseius largoensis also displayed a higher oviposition rate (2.19 eggs/female/day) than A. swirskii and P. lenis (1.79 and 1.78 eggs/female/day, respectively). Moreover, it exhibited the highest fecundity (25.34 eggs/female), followed by P. lenis (24.23 eggs/female) and A. swirskii (22.86 eggs/female). These variations led to A. largoensis having the highest intrinsic rate of increase (rm) at 0.209, followed by A. swirskii at 0.188, and P. lenis at 0.165. However, when the predatory mites were provided with first instars of F. occidentalis, A. swirskii demonstrated a faster immature development period for both males (7.67 days) and females (7.59 days) as compared with P. lenis (9.00 days and 7.86 days, respectively) and A. largoensis (8.47 days and 8.61 days, respectively). While the oviposition rates of P. lenis (1.92 eggs/female/day) and A. swirskii (1.90 eggs/female/day) were similar when feeding on this prey, A. largoensis produced fewer eggs (1.83 eggs/female/day). Further, A. swirskii exhibited the highest fecundity (31.93 eggs/female), followed by A. largoensis (25.71 eggs/female) and P. lenis (23 eggs/female). Consequently, the intrinsic rate of increase (rm) on thrips first instars was highest in A. swirskii (0.190), followed by A. largoensis (0.186), and P. lenis (0.176). In summary, our findings indicate that in terms of life history parameters A. largoensis performs optimally when feeding on thrips eggs, whereas A. swirskii performs best when preying on the mobile first instars of the thrips. These insights into the dietary preferences and reproductive capabilities of the studied predatory mite species have important implications for their potential use as biological control agents against F. occidentalis in agricultural settings.

Sublethal effects of a spiromesifen and abamectin combination on Tetranychus urticae (Acari: Tetranychidae) and its predators Phytoseiulus persimilis and Amblyseius swirskii (Acari: Phytoseiiidae).

The two-spotted spider mite, Tetranychus urticae Koch (TSSM), is an important cosmopolitan pest of agricultural crops that is often managed in greenhouses by augmentation of predatory mites in combination with acaricides. Here we examined the transgenerational effects of low lethal concentrations of a widely-used acaricide, Oberon Speed® (a combination of spiromesifen and abamectin), on the life history traits and population growth of T. urticae and two of its predators, Phytoseiulus persimilis Athias-Henriot and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae). The concentrations employed corresponded to the LC10, LC20 and LC30 values estimated for TSSM protonymphs 48 h post-exposure in a topical bioassay, which yielded an LC50 value of 207.2 ppm. Parental exposure of TSSM to all three low concentrations increased the total developmental time of progeny; both the LC20 and LC30 treatments reduced adult longevity and number of oviposition days, but only the LC30 treatment increased the preoviposition period. Similarly, both the LC20 and LC30 treatments significantly reduced life table parameters (r, R0, λ, and GRR), and increased generation time (T) and population doubling time (DT). Although maternal exposure to the acaricide had various impacts on progeny life history, A. swirskii was less affected than P. persimilis, suggesting the former species would be more compatible for integration with Oberon Speed® for control of T. urticae in greenhouse vegetable production.

Biological control of mites by xerophile Eurotium species isolated from the surface of dry cured ham and dry beef cecina.

Some meat dry products, including dry cured ham and dry beef cecina, are cured in cellars at moderately cold temperature allowing the growth of a lawn of fungi on their surface. During the curing process, frequently these products became contaminated with fungivore mites of the Acaridae family that feed on fungal mycelium and spores. AIMS: The aim of this article is to study the possible biological control of mites by fungi that form part of the normal microbiota of these meat products. METHODS AND RESULTS: Some yellow/orange pigmented fungi growing on the ham surface decreased the proliferation of mites; therefore, we isolated from ham and cecina xerophilic yellow/orange coloured fungal strains that were identified as members of the genus Eurotium (recently reclassified as Aspergillus section Aspergillus). Using molecular genetic tools, we have identified 158 strains as Eurotium rubrum (Aspergillus ruber), Eurotium repens (Aspergillus pseudoglaucus) and Eurotium chevalieri (Aspergillus chevalieri). Two strains, E. rubrum C47 and E. rubrum C49, showed strong miticidal activity. The toxic compound(s) are associated with the formation of cleistothecia. In synchronized mite development experiments, we observed that all stages of the mite lifecycle were inhibited by the E. rubrum C47 strain. In addition, we searched for miticidal activity in 13 culture collection Eurotium strains isolated from different habitats, and found that only one, Eurotium cristatum NRRL 4222 (Aspergillus cristatus) has a strong miticidal activity. CONCLUSIONS: These fungal strains have proliferated on the surface of ham and cecina for decades, and possibly have acquired miticidal activity as a resistance mechanism against fungivores. SIGNIFICANCE AND IMPACT OF THE STUDY: Biological control of infecting mites by favouring growth of E. rubrun C47, in place of the normal mixed population of Aspergillus and Penicillium, is an attractive approach to control mite infestations.

Low-temperature storage of the poultry red mite, Dermanyssus gallinae, facilitates laboratory colony maintenance and population growth.

The poultry red mite, Dermanyssus gallinae, is currently the most common ectoparasite affecting egg-laying hens. Since continuous culture of D. gallinae on birds is a biologically and economically costly endeavour, storage techniques for mites are urgently needed. Effects of temperature on adult and nymph survival were first studied to optimize storage conditions. Then, fecundity of D. gallinae was studied after mites were stored at optimal storage conditions. Results showed the survival rates of protonymphs (42.11%), deutonymphs (8.19%) and females (19.78%) at 5°C after 84 days were higher than those at 0, 25 and 30°C. Thereafter the fecundity and the capability of re-establishing colonies of D. gallinae were evaluated after they were stored for 40 and 80 days at 5°C. After storage, the mean number of eggs showed no statistical difference between treated (5°C for 40 or 80 days) and control groups (25°C for 7 days), while the hatching rates of eggs were in all cases above 97%. The dynamic changes of mite populations and egg numbers showed similar trends to the control group after the stored adult or nymph mites were fed on chicks. Dermanyssus gallinae can be successfully stored at 5°C for 80 days with no interference with the fecundity of mites, and the stored mites could re-establish colonies successfully. Adults and nymphs were two main stages with capability for low temperature storage. These results suggest that low temperature storage is a viable option for colony maintenance of D. gallinae under laboratory conditions.

Mode of entry of secondary metabolites of the bacteria Xenorhabdus szentirmaii and X. nematophila into Tetranychus urticae, and their toxicity to the predatory mites Phytoseiulus persimilis and Neoseiulus californicus.

The bacterial metabolites in supernatants of Xenorhabdus species have acaricidal activity, but this mode of entry into mites has not yet been elucidated. Herein, we report on the possible mode of entry of Xenorhabdus szentirmaii and Xenorhabdus nematophila supernatants into Tetranychus urticae (Acari: Tetranychidae) adult females. We also assessed the toxicity of the supernatants against the developmental stages of the predatory mites, Phytoseiulus persimilis and Neoseiulus californicus (Acari: Phytoseiidae). Experiments were conducted at 25 ± 1 °C, 70 ± 5% relative humidity, and 16:8h light:dark conditions. Our data showed that the bioactive acaricidal compound is most effective (86.5 to 89% mortality) when the entire integument of T. urticae comes in contact with it compared to contact of the ventral side only (26.5-34%). Against P. persimilis and N. californicus at 6 days post-application (dpa), the eggs were not affected by the X. szentirmaii or X. nematophila supernatant, whereas mortality of the mobile stages (larva, protonymph, deutonymph, adult) was 18.5% to 39.2%. Overall, the predatory mites were less affected by the bacterial metabolites than T. urticae. We hypothesize that the differences in morphology such as longer legs and thicker cuticle, as well as the diet of the predatory mites, reduce the contact of the body parts to the supernatant-treated surfaces. We need to isolate, identify, and characterize the X. szentirmaii and X. nematophila metabolite(s) and demonstrate efficacy to pestiferous mites and safety to plants, non-target organisms and the environment before it can be used as an acaricide.

Genomic insights into mite phylogeny, fitness, development, and reproduction.

BACKGROUND: Predatory mites (Acari: Phytoseiidae) are the most important beneficial arthropods used in augmentative biological pest control of protected crops around the world. However, the genomes of mites are far less well understood than those of insects and the evolutionary relationships among mite and other chelicerate orders are contested, with the enigmatic origin of mites at one of the centres in discussion of the evolution of Arachnida. RESULTS: We here report the 173 Mb nuclear genome (from 51.75 Gb pairs of Illumina reads) of the predatory mite, Neoseiulus cucumeris, a biocontrol agent against pests such as mites and thrips worldwide. We identified nearly 20.6 Mb (~ 11.93% of this genome) of repetitive sequences and annotated 18,735 protein-coding genes (a typical gene 2888 bp in size); the total length of protein-coding genes was about 50.55 Mb (29.2% of this assembly). About 37% (6981) of the genes are unique to N. cucumeris based on comparison with other arachnid genomes. Our phylogenomic analysis supported the monophyly of Acari, therefore rejecting the biphyletic origin of mites advocated by other studies based on limited gene fragments or few taxa in recent years. Our transcriptomic analyses of different life stages of N. cucumeris provide new insights into genes involved in its development. Putative genes involved in vitellogenesis, regulation of oviposition, sex determination, development of legs, signal perception, detoxification and stress-resistance, and innate immune systems are identified. CONCLUSIONS: Our genomics and developmental transcriptomics analyses of N. cucumeris provide invaluable resources for further research on the development, reproduction, and fitness of this economically important mite in particular and Arachnida in general.

Immune mechanisms in human and canine demodicosis: A review.

Demodex mites are saprophytic parasites of the mammalian skin, mostly found in or near pilosebaceous units of hairy regions. While they can be found in healthy humans and animals without causing any clinical manifestations, they were suggested to create pathogenic symptoms when they appear in high densities under favourable conditions (ie, demodicosis). Nevertheless, their role as the primary causative agent of the pathogenic conditions in humans is debated today. Canine demodicosis, which is highly prevalent in certain dog breeds, provides a valuable tool for studying the pathogenesis of human demodicosis. Canine and human demodicosis are caused by different Demodex species, and the clinical manifestations in former could be life-threatening. Nevertheless, current literature suggests similar immune responses and immune evasion mechanisms in human and canine demodicosis; cellular immunity appeared to have a central role in protection against demodicosis, and Demodex mites were shown to influence both innate and adaptive immune response to escape immune attack. The aim of this review is to summarize the relevant literature on demodicosis obtained from studies conducted on both organisms, and draw the attention to the effect of mite-associated factors (eg, microbiota) on the different clinical manifestations displayed during human and canine demodicosis.

Critically Appraised Topic on Adverse Food Reactions of Companion Animals (8): Storage Mites in Commercial Pet foods.

BACKGROUND: Dogs with year-round atopic dermatitis are often sensitized to Dermatophagoides house dust mites (HDM). Storage mites (SM) are known to grow on cereal-rich foods. Tyrophagus SM can exacerbate clinical signs of allergy in laboratory dogs sensitized to HDM. Consequently, atopic dogs with high-levels of HDM-specific IgE are likely to have a flare of signs after eating a food contaminated with SM; the development of such flares would lead to a false positive diagnosis of food allergy. Herein, we reviewed the published evidence about the growth of SM on commercial dry pet foods. RESULTS: We searched two databases on January 25, 2019 for articles providing original information on the growth of SM on commercial dog foods. We found ten articles, five reporting results of laboratory experiments and five from field studies. Storage mites, especially Tyrophagus putrescentiae, can multiply on protein- and fat-rich dog foods. The population growth is higher when the initial mite density is high and when kibbles are crushed. When storage conditions lead to the overgrowth of molds on the kibbles, the mite proliferation is higher. Storage mites do not bore holes in food packages but invade bags via defective seals. In the field, SM contamination usually is undetectable in newly-opened commercial dog foods, and, if present, their number is low. When newly-purchased bags are stored in temperate conditions indoors, little overgrowth-if any-of SM occurs. However, when kept in environmental conditions with higher temperature and humidity, Tyrophagus mites will enter and proliferate in sealed food packages. CONCLUSIONS: Commercial dry pet foods should be kept indoors and sealed to decrease the risk of contamination with SM. When performing dietary restriction (elimination) and provocation trials for the diagnosis of food allergies in dogs, it seems preferable to choose newly-purchased bags-of both original and testing diets-to reduce the probability of their contamination with SM, especially Tyrophagus putrescentiae. In case of doubt about the presence of SM in any of these foods, one should perform food challenges with single home-cooked ingredients. Storage mite contamination might lead to an erroneous diagnosis of food allergy in HDM-sensitized dogs.

Screening of reference genes using real-time quantitative PCR for gene expression studies in Neoseiulus barkeri Hughes (Acari: Phytoseiidae).

A stable reference gene is a key prerequisite for accurate assessment of gene expression. At present, the real-time reverse transcriptase quantitative polymerase chain reaction has been widely used in the analysis of gene expression in a variety of organisms. Neoseiulus barkeri Hughes (Acari: Phytoseiidae) is a major predator of mites on many important economically crops. Until now, however, there are no reports evaluating the stability of reference genes in this species. In view of this, we used GeNorm, NormFinder, BestKeeper, and RefFinder software tools to evaluate the expression stability of 11 candidate reference genes in developmental stages and under various abiotic stresses. According to our results, ß-ACT and Hsp40 were the top two stable reference genes in developmental stages. The Hsp60 and Hsp90 were the most stable reference genes in various acaricides stress. For alterations in temperature, Hsp40 and α-TUB were the most suitable reference genes. About UV stress, EF1α and α-TUB were the best choice, and for the different prey stress, ß-ACT and α-TUB were best suited. In normal conditions, the ß-ACT and α-TUB were the two of the highest stable reference genes to respond to all kinds of stresses. The current study provided a valuable foundation for the further analysis of gene expression in N. barkeri.

Do the pattern and strength of species associations in ectoparasite communities conform to biogeographic rules?

We tested whether biogeographic patterns characteristic of species diversity and composition may also apply to community assembly by investigating geographic variation in the pattern (PSA) (aggregation versus segregation) and strength of species associations (SSA) in flea and mite communities harbored by small mammalian hosts in Western Siberia. We asked whether (a) there is a relationship between latitude and PSA or SSA and (b) similarities in PSA or SSA follow a distance decay pattern or if they are better explained by variation in environmental factors (altitude, amount of vegetation, precipitation, and air temperature). We used a sign of a co-occurrence metric (the C-score) as an indicator of PSA and its absolute standardized value as a measure of SSA. We analyzed data using logistic and linear models, generalized dissimilarity modeling (GDM), and a logistic version of the multiple regression on distance matrices (MRM). The majority of the C-scores of the observed presence/absence matrices indicated a tendency to species aggregation rather than segregation. No effect of latitude on PSA or SSA was found. The dissimilarity in PSA was affected by environmental dissimilarity in mite compound communities only. A relatively large proportion of the deviance of spatial variation in SSA was explained by the GDMs in infracommunities, but not component communities, and in only three (of seven) and two (of eight) host species of fleas and mites, respectively. The best predictors of dissimilarity in SSA in fleas differed between host species, whereas the same factor (precipitation) was the best predictor of dissimilarity in SSA in mites. We conclude that PSA and SSA in parasite communities rarely conform to biogeographic rules. However, when a biogeographic pattern is detected, its manifestation differs among hosts and between ectoparasite taxa.

Is the spatial distribution of lentic water mite assemblages (Acari: Hydrachnidia) governed by prey availability?

Predation is a biotic interaction that links water mites to different taxonomic groups of benthic invertebrates. Diptera larvae (Chironomidae) and microcrustaceans (Cladocera, Copepoda, Ostracoda) are known to be the most commonly preferred prey by water mites. Although these predatory interactions are known from observations and ex situ investigations, the distribution patterns and co-occurrence of water mites and their prey in littoral lentic habitats have been poorly studied. Our goal was to determine whether predation might serve as a significant factor in water mite assemblage composition and distribution. Samples were taken from littoral zones of 21 artificial lakes (reservoirs) in the Dinaric Western Balkan ecoregion of Croatia. At every site, 10 samples were collected with regard to shore slope in depth zones of up to 1 m. In total 490 samples were collected from April 2016 to July 2017. Data analysis showed that the spatial distribution of water mites was partially correlated with the environmental parameters we measured (explaining 45.1% of total water mite variation). A positive correlation between water mite abundance and diversity and depth gradient (favouring more stable conditions in deeper parts of the littoral zone) was also observed. Finally, water mite abundance and species richness variation were found to be best predicted by the abundance of potential prey groups. Predation was statistically determined to be a strong dispersion variable, most probably influencing both spatial distribution and composition of water mite assemblages.

The gut epithelium from feeding to fasting in the predatory soil mite Pergamasus longicornis (Mesostigmata: Parasitidae): one tissue, two roles.

A review of acarine gut physiology based on published narratives dispersed over the historical international literature is given. Then, in an experimental study of the free-living predatory soil mite Pergamasus longicornis (Berlese), quantitative micro-anatomical changes in the gut epithelium are critically assessed from a temporal series of histological sections during and after feeding on larval dipteran prey. An argued functional synthesis based upon comparative kinetics is offered for verification in other mesostigmatids. Mid- and hind-gut epithelia cell types interconvert in a rational way dependent upon the physical consequences of ingestion, absorption and egestion. The fasted transitional pseudo-stratified epithelium rapidly becomes first squamous on prey ingestion (by stretching), then columnar during digestion before confirmed partial disintegration (gut 'lumenation') during egestion back to a pseudo-stratified state. Exponential processes within the mid- and endodermic hind-gut exhibit 'stiff' dynamics. Cells expand rapidly ([Formula: see text] 22.9-49.5 min) and vacuolate quickly ([Formula: see text] 1.1 h). Cells shrink very slowly ([Formula: see text] 4.9 days) and devacuolate gently ([Formula: see text] 1.0-1.7 days). Egestive cellular degeneration has an initial [Formula: see text] 7.7 h. Digestion appears to be triggered by maximum gut expansion-estimated at 10 min post start of feeding. Synchrony with changes in gut lumen contents suggests common changes in physiological function over time for the cells as a whole tightly-coupled epithelium. Distinct in architecture as a tissue over time the various constituent cell types appear functionally the same. Functional phases are: early fluid transportation (0-1 h) and extracellular activity (10-90 min); through rising food absorption (10 min to [Formula: see text] day); to slow intracellular meal processing and degenerative egestive waste material production (1 to [Formula: see text] days) much as in ticks. The same epithelium is both absorptive and degenerative in role. The switch in predominant physiology begins 4 h after the start of feeding. Two separate pulses of clavate cells appear to be a mechanism to facilitate transport by increasing epithelial surface area in contact with the lumen. Free-floating cells may augment early extracellular lumenal digestion. Possible evidence for salivary enzyme alkaline-related extra-corporeal digestion was found. Giant mycetome-like cells were found embedded in the mid-gut wall. Anteriorly, the mid-gut behaves like a temporally expendable food processing tissue and minor long-term resistive store. Posteriorly the mid-gut behaves like a major assimilative/catabolic tissue and 'last-out' food depot (i.e., a 'hepatopancreas' function) allowing the mite to resist starvation for up to 3.5 weeks after a single meal. A 'conveyor-belt' wave of physiology (i.e., feeding and digestion, then egestion and excretion) sweeps posteriorly but not necessarily pygidially over time. Assimilation efficiency is estimated at 82%. The total feeding cycle time histologically from a single meal allowing for the bulk of intracellular digestion and egestive release is not 52.5 h but of the order of 6 days ([Formula: see text] total gut emptyings per day), plus typically a further 3 days for subsequent excretion to occur. Final complete gut system clearance in this cryptozooid may take much longer ([Formula: see text] days). A common physiology across the anactinotrichid acarines is proposed. A look to the future of this field is included.

Life table parameters of the red palm mite Raoiella indica (Acari: Tenuipalpidae) at various temperatures and for sexual and asexual reproduction.

The red palm mite, Raoiella indica Hirst, is a threat to coconut, banana and native Arecaceae and Heliconiaceae in Brazil. This mite originated in the Eastern Hemisphere and was first reported in 2004 in the Americas, where the pest is spreading quickly and causing severe damage to its host plants. The objective of this work was to determine the life-history parameters of R. indica at constant temperatures, estimate its thermal requirements [threshold temperature (Tb) and thermal constant (K)] and also compare its life table parameters between sexual reproduction and parthenogenesis. The life tables were constructed on leaflets of Adonidia merrillii at 15, 20, 24, 27, 30 and 34 °C and 65% RH and a 12-h photoperiod. The longevity and the number of laid eggs of non-copulated adult females were evaluated at 27 °C. Raoiella indica had complete development, from egg to adult, only at 20, 24, 27 and 30 °C. At 15 °C, the eggs did not hatch, and at 34 °C, the mites survived only until the larval stage. For sexual reproduction, the optimal temperature was 27 °C, under which the reproductive parameters were higher. The reproductive parameters for sexual reproduction were higher than those for parthenogenesis. The Tb was 14.79 °C, and the thermal constant was 208.33 degree days. The life parameters estimated in this study can be used for modelling and predicting the population growth of R. indica in the field and consequently for improving their management strategies.

Biological and demographic parameters of Tegolophus brunneus (Acari: Eriophyidae) in citrus.

The brown citrus rust mite, Tegolophus brunneus Flechtmann (Acari: Eriophyidae), causes citrus rust, as does Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae). As the citrus rust damage has intensified in recent years and T. brunneus has been reported in high population levels in several regions of Brazil, this mite has caused concern to growers and technicians. Because T. brunneus has been little studied and its bioecological characteristics are unknown, this study investigated the biological and demographic parameters of T. brunneus on citrus fruits under laboratory conditions. Our results showed that the egg incubation period and viability were 3.0 and 94.5%, respectively. The larval and nymphal stage durations were 1.1 and 2.8 days, respectively. The development time of the immature stage was 6.9 days, with 92.3% survival. When females and males were maintained together, the sex ratio of offspring was 0.7; virgin females produced only males. The pre-oviposition (from adult emergence to the first egg) and total pre-oviposition (egg-to-egg) periods were 1.6 and 8.5 days, respectively. Fecundity was 8.5 eggs, and female and male longevities were 13.2 and 11.4 days, respectively. The estimate of demographic parameters indicated that the Ro and T of T. brunneus were 6.45 offspring and 13.0 days, and r and λ were 0.142 and 1.153 day-1, respectively. These results suggest that T. brunneus has high growth potential on citrus trees. Therefore, management strategies may be required to reduce the population levels and damage caused by T. brunneus in citrus groves.

Inter- and intraspecific variability of morphological and molecular characters in Allothrombium species, with special reference to Allothrombium fuliginosum.

Morphology-based identification of Allothrombium spp., in view of the limited knowledge of intraspecific variation, hinders the recognition of species borders and affects the views on the actual distribution of species. Therefore, identification will benefit from reference to molecular methods. The separate species identity of specimens putatively representing Allothrombium fuliginosum and A. pulvinum, both reported as widely distributed in the Palaearctic region and considered as potential biological control agents, was checked using morphological and molecular analyses. The representatives of various Allothrombium spp. collected in the Palaearctic were included in the analysis in order to ascertain the distance between species. The results of the morphological examination, supported by statistical inference, along with the comparison of COI and/or ITS2 sequences, weaken the hypothesis of synoccurrence of both species in the Palaearctic region. Hence, we hypothesize that A. fuliginosum is widely distributed in the Palaearctic, whereas A. pulvinum should be regarded a Nearctic species.