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.

Molecular phylogeny of Phyllocoptes associated with roses discloses the presence of a new species

There are few plant maladies as devastating as rose rosette, a disease caused by an eriophyoid -transmitted virus. Rosette annihilates roses across North America, and to date, there is a single verified vector of the virus, Phyllocoptes fructiphilus Keifer. In direct contrast to the importance of rose for the ornamental industry there is limited knowledge on the eriophyoids that inhabit roses in North America and even less information on their vectoring capacities. This study dissects the genetic diversity of the eriophyoid fauna in rosette-affected hotspots and provides evidence of the existence of an undescribed species named Phyllocoptes arcani sp. nov., that could potentially be a second vector of the rosette virus.

New findings of spinturnicid mites (Mesostigmata: Gamasina: Spinturnicidae) from the Caucasus

The Caucasus is a large region in Eurasia consisting of four countries: Russia, Georgia, Azerbaijan, and Armenia. Although it is one of the biodiversity hotspots in the world, the bat ectoparasite fauna has been poorly studied. To promotionally fill in the gaps regarding bat ectoparasites, we conducted five field surveys on bats and their ectoparasites at nine localities within the region between April 2016 and March 2021. Eight species and subspecies of spinturnicid mites were recorded over the surveys: Eyndhovenia euryalis oudemansi, Spinturnix acuminata acuminata, S. emarginata, S. myoti, S. nobleti, S. plecotina, S. psi, and S. punctata. Among them, three species, Spinturnix emarginata, S. nobleti and S. punctate, are newly recorded from the Caucasus region, and one each of subspecies and species, Eyndhovenia euryalis oudemansi and S. plecotina, are newly recorded from Georgia. In addition, Myotis tschuliensis was recorded as a new host species of S. myoti.

Ultrastructure of the intestinal system in unfed larvae of Limnesia maculata (O.F. Müller, 1776) (Acariformes, Limnesiidae)

The intestinal system of unfed fresh-water mite larvae Limnesia maculata (O.F. Müller, 1776) (Acariformes, Limnesiidae) has been studied with transmission electron microscopy. The intestinal system is composed of the foregut, including the pharynx and the esophagus, the sac-like blind midgut and the excretory organ. The pharynx begins with the mouth covered by the labrum. The pharynx runs along the bottom of the gnathosoma and shows ventral dilators. No valves are expressed between the pharynx and the esophagus. The esophagus possesses strongly plicate walls and, before entering the midgut, passes through the brain. The sac-like midgut does not reveal a well-pronounced lumen, developed epithelium and separate lobes. It consists of the two cell types of endoderm origin mixed in the midgut volume. The first type - the vacuolated cells - does not possess Golgi bodies and lysosomal apparatus and shows electron-lucent vacuoles with a granular inclusion inside. These cells apparently do not take part in digestion of the embryonic yolk. The second type - the non-vacuolated cells - shows both, a well developed Golgi complex and large heterolysosomes, and obviously digests the embryonic yolk. Consequently, they may be attributed as specialized vitellophages. Nevertheless, both cell types may take part in formation of the definitive midgut epithelium. The sac-like thin-walled excretory organ is strongly dilated and contains the embryonic wastes in the form of electron-dense globules and birefringent particles. No muscle envelope surrounds the excretory organ. The embryonic wastes together with wastes accumulated during feeding may be evacuated from the organ only after completion of feeding. The excretory canal on this developmental stage is not connected with the excretory organ. It opens to the outside with a simple slit-like excretory pore. Before feeding, larvae have to pass the process of the post-molt development before their midgut would be ready to receive nutrients.

Temperature stress induces mites to help their carrion beetle hosts by eliminating rival blowflies

Ecological conditions are known to change the expression of mutualisms though the causal agents driving such changes remain poorly understood. Here we show that temperature stress modulates the harm threatened by a common enemy, and thereby induces a phoretic mite to become a protective mutualist. Our experiments focus on the interactions between the burying beetle Nicrophorus vespilloides, an associated mite species Poecilochirus carabi and their common enemy, blowflies, when all three species reproduce on the same small vertebrate carrion. We show that mites compete with beetle larvae for food in the absence of blowflies, and reduce beetle reproductive success. However, when blowflies breed on the carrion too, mites enhance beetle reproductive success by eating blowfly eggs. High densities of mites are especially effective at promoting beetle reproductive success at higher and lower natural ranges in temperature, when blowfly larvae are more potent rivals for the limited resources on the carcass.

New Species of the Genus Periglischrus (Acari: Spinturnicidae) from Monophyllus Bats (Chiroptera: Phyllostomidae) in the West Indies, Including a Morphometric Analysis of Its Intraspecific Variation

The discovery of a new species, Periglischrus empheresotrichus, was determined through a review of museum collections, as well as a field survey of ectoparasites of island bats. This new species parasitizes on two bat species of the genus Monophyllus Leach, the Greater Antillean Long-tongued bat Monophyllus redmani Leach and the Lesser Antillean Long-tongued bat Monophyllus plethodon Miller. The female, male, deuthonymphs, and protonymph are described and illustrated. P. empheresotrichus n. sp. has an insular distribution, we evaluated the morphological variation of the adult populations, and concluded that intra-specific variation is correlated both with host species and locality (island) in the West Indies.

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.

Oppia nitens C.L. Koch, 1836 (Acari: Oribatida): Current Status of Its Bionomics and Relevance as a Model Invertebrate in Soil Ecotoxicology

The oribatid soil mite Oppia nitens C.L. Koch, 1836, is a model microarthropod in soil ecotoxicity testing. This species has a significant role in supporting soil functions and as a suitable indicator of soil contamination. Despite its significance to the environment and to ecotoxicology, however, very little is known of its biology, ecology, and suborganismal responses to contaminants in the soil. In the present review, we present detailed and critical insights into the biology and ecology of O. nitens in relation to traits that are crucial to its adaptive responses to contaminants in soil. We used a species sensitivity distribution model to rank the species sensitivity to heavy metals (cadmium and zinc) and neonicotinoids (imidacloprid and thiacloprid) compared with other standardized soil invertebrates. Although the International Organization for Standardization and Environment and Climate Change Canada are currently standardizing a protocol for the use of O. nitens in soil toxicity testing, we believe that O. nitens is limited as a model soil invertebrate until the molecular pathways associated with its response to contaminants are better understood. These pathways can only be elucidated with information from the mites' genome or transcriptome, which is currently lacking. Despite this limitation, we propose a possible molecular pathway to metal tolerance and a putative adverse outcome pathway to heavy metal toxicity in O. nitens. Environ Toxicol Chem 2019;38:2593-2613. © 2019 SETAC.

Ketalization of 2-heptanone to prolong its activity as mite repellant for the protection of honey bees

BACKGROUND

2-Heptanone is a volatile liquid known to be effective in protecting honey bees from parasitic mite infestations in hives. The present study aimed to show that chemical derivatives of 2-heptanone would release the ketone for a significantly longer time than it takes for the pure ketone to evaporate and preferably for as long as two brood cycles of a honey bee (42 days).

RESULTS

A liquid ketal of 2-heptanone with glycerol (Glyc-Ket) and solid ketals of the ketone with polyvinyl alcohol (PVAl-Ket), containing different amounts of the ketone, were synthesized. The fully resolved ¹ H and ¹³ C nuclear magenetic resonance (NMR) spectra of the ketals are discussed. In the case of the polymer, differential scanning calorimetry (DSC) of a ketal was also compared with the unketalized polyvinyl alcohol. The length of time for which 2-heptanone was released by the ketals was determined by gas chromatography-mass spectrometry of the headspace. In the case of Glyc-Ket, the concentration of the 2-heptanone in the liquid phase was also monitored by ¹ H NMR spectroscopy. The deketalization was pH dependent, ranging between 2.0 and 2.5 for Glyc-Ket and between 2.0 and 3.5 for PVAl-Ket.

CONCLUSION

Under bee hive conditions, the release of 55 mmol 2-heptanone from Glyc-Ket lasted for 42 days, whereas the release of the ketone from the PVAl-Ket with a similar amount of the ketone lasted for 23 days, versus a maximum of 17 days for an equivalent amount of the pure ketone. These ketals therefore have the potential to be effective mite repellants for the protection of honey bees. © 2019 Society of Chemical Industry.

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 R_o 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.

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, β-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, β-ACT and α-TUB were best suited. In normal conditions, the β-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.

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.

Detection and identification of dust mite allergens in the air conditioning filters in Chandigarh, India

Modern lifestyle with the increasing use of air conditioner (AC) has been linked with breathing difficulties, irritation, dryness, and other symptoms. Hence, dust mites were isolated from AC filters, which causes allergic diseases. A total of 95 dust samples were collected from AC filters from hospitals, guest house, office, school, and homes in Chandigarh, India. The highest concentration of dust mites was detected from hospitals (9/g), offices (7/g), households (6/g), guest houses (3/g), and schools (0/g). Based on the morphology of dust mites observed under a light microscope, Dermatophagoides and Acarus species were found most common. Indoor air quality was also monitored to find out their relation with dust mites present in AC filters. Further, the respiratory health status of indoor facility users was also assessed using a standard questionnaire as a study tool. It was seen that 55.3% of male among the total respondents were having an allergy and only 44.7% of the females had an allergy. The allergy among the male respondents (55.3%) was significantly more (p < 0.05) in comparison with female respondents (44.7%). Some of the respondents also reported a family history of rhinitis (31.9%), asthma (12.8%), recurrent urticaria (6.4%), and conjunctivitis (6.4%). Interestingly, 23.4% of study participants reported that they get disturbed by the use of AC and house dust was found to be the most triggering factor in enhancing the symptoms of allergy. Thus, it is recommended that air conditioner filters should be cleaned regularly to prevent the accumulation of the dust mites and related allergens on filter dust.

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.

Effects of root and leaf litter identity and diversity on oribatid mite abundance, species richness and community composition

Habitat heterogeneity is an important driver of aboveground species diversity but few studies have investigated effects on soil communities. Trees shape their surrounding by both leaf litter and roots generating small scale heterogeneity and potentially governing community patterns of soil organisms. To assess the role of vegetation for the soil fauna, we studied whether tree species (Fagus sylvatica L., Acer pseudoplatanus L., Fraxinus excelsior L., Tilia cordata Mill.), markedly differing in leaf litter quality and root associated mycorrhizal symbionts, affect oribatid mite communities by shaping below- and aboveground resources and habitat complexity and availability. Oribatid mite abundance, species richness, community structure and the proportion of litter living and parthenogenetic individuals were analyzed and related to microbial biomass and the amount of remaining litter mass. Although leaf litter species with higher nutritional values decomposed considerably faster, microbial biomass only slightly differed between leaf litter species. Neither root species nor leaf litter species affected abundance, species richness or community structure of oribatid mites. However, root species had an effect on the proportion of parthenogenetic individuals with increased proportions in the presence of beech roots. Overall, the results suggest that identity and diversity of vegetation via leaf litter or roots are of minor importance for structuring oribatid mite communities of a temperate forest ecosystem.

Supplementary food for Neoseiulus californicus boosts biological control of Tetranychus urticae on strawberry

BACKGROUND

A wide range of supplementary food resources can be offered to generalist predatory mites to improve their survival and reproduction and enhance their persistence in the environment. We investigated the relative suitability of different pollen types for the survival and reproduction of Neoseiulus californicus and its life history on a mixed diet of pollen and prey. We also evaluated the population dynamics of Tetranychus urticae in the presence of N. californicus with or without pollen, and in comparison to Phytoseiulus macropilis.

RESULTS

Survival and reproduction of N. californicus adults were satisfactory on exclusive diets of T. urticae, cattail pollen, palm pollen and bee pollen. However, mites did not reproduce when fed only pollen during both immature and adult stages. Both predatory mites successfully controlled T. urticae. Although the specialist P. macropilis was more efficient in suppressing the pest population in the short term, it abandoned plants at low prey densities, whereas N. californicus performed better and persisted longer under prey scarcity.

CONCLUSION

N. californicus is an efficient biological control agent of T. urticae and the provision of supplementary food could retain them in the crop prior to the arrival of the pest or in periods of prey scarcity. © 2019 Society of Chemical Industry.

Biology and predation capacity of Parasitus bituberosus (Acari: Mesostigmata: Parasitidae) on Frankliniella occidentalis (Thysanoptera: Thripidae), and free-living nematodes as its complementary prey

BACKGROUND

Parasitus bituberosus is common in rose fields and nearby vegetation around Bogotá. In rearing units, it is often aggregated, feeding on Frankliniella occidentalis edaphic phases. Preliminary observations suggested predator immatures can not reach adulthood if isolated. The objectives were to evaluate the suitability of F. occidentalis as prey for P. bituberosus, to evaluate free-living nematodes as complementary food, and to confirm the aggregation effect on predator biology. Aggregation types: (1) isolated mites, (2) mites paired only as deutonymphs and early adulthood, and (3) mites always paired. Diets: thrips (T), nematodes (N) and thrips + nematodes (NT).

RESULTS

Parasitus bituberosus juveniles did not feed on live F. occidentalis, but developed and oviposited on nematodes. Approximately 77% of the isolated mites died as immatures. Mortality was low (21-23%) when predators were paired at least in the deutonymph and the early adult phase. Female daily predation rates were comparable to other predators on F. occidentalis (≥2.5). Continuously paired mites had high biotic potential, especially when the diet included nematodes (r_m  ≥ 0.33; R_o  ≥ 33.90; daily oviposition rate ≥ 10.9).

CONCLUSION

The results of this study warrant further investigation of this predator, to evaluate methods for its mass production, inclusion in conservation biocontrol programs and performance against the pest at a larger scale. © 2019 Society of Chemical Industry.

Context dependent life-history shift in Macrodinychus sellnicki mites attacking a native ant host in Colombia

Ant parasitoidism has been reported in seven of the 26 recognized species of the mite genus Macrodinychus (Machrodynichidae). Macrodynichus sellnicki, previously reported as a parasitoid of the invasive ant Nylanderia fulva in Colombia, is now reported, in the same region, as attacking a native host, Ectatomma sp. 2 (E. ruidum complex). The mite develops within the protective silk cocoon of an Ectatomma pupa and waits for the emergence of the young ant before leaving the cocoon, unmolested. Overall nest prevalence was relatively high (34.6% of the 52 nests containing cocoons) but pupae prevalence was low (4.0%, n = 1401 cocoons). Mite life-history (parasite or parasitoid) was context dependent, shifting according to the intensity of the attack on a same host. Contrary to the strictly parasitoidic association of M. sellnicki with N. fulva, single mite attacks against E. ruidum did not result in host killing and solitary M. sellnicki (78.6% of the cases) behaved as parasites. However, in 21.4% of the attacks (0.9% of all available host pupae) more than one mite was involved and behaved as parasitoids, draining the host of its internal fluids and killing it. This is the first association of a macrodinychid mite with a species of the subfamily Ectatomminae, and the first ant associated mite for which such a context dependent life-style shift is described.

Darkness increases the population growth rate of the poultry red mite Dermanyssus gallinae

BACKGROUND

The poultry red mite (PRM), Dermanyssus gallinae, is one of the most economically deleterious ectoparasites affecting egg-laying hens worldwide. It may be possible to control D. gallinae populations by manipulating lighting regimes within poultry units. However, no studies have clearly shown the effects of darkness on the population growth rate of D. gallinae.

METHODS

The effect of darkness on the population growth rate of D. gallinae was investigated, together with the first description of the molecular identity of the mite from China. Mite variables under two lighting regimens (1:23 h L:D and 12:12 h L:D) were compared, including number of mites and eggs, survival and feeding rates, engorgement, oviposition, hatchability and the life-cycle of D. gallinae.

RESULTS

The results showed that the number of mites (13,763 ± 956) and eggs (5424 ± 317) in the rearing system with prolonged darkness of 1:23 h L:D at 4th week were 2.4- and 3.6-fold higher than those under a conventional lighting regimen of 12:12 h L:D, respectively. The feeding rates of mites under prolonged darkness ranged from 36.7 ± 1.1% to 52.0 ± 7.0%, which were significantly higher than those under conventional lighting regimen (ranging from 22.6 ± 1.9% to 37.3 ± 1.6%). The mean weight of engorged females (0.26 ± 0.01 mg) and the mean number of eggs per female (on average 5.87 ± 0.36) under prolonged darkness were significantly higher than those under conventional lighting regimen (0.22 ± 0.01 mg and 3.62 ± 0.31, respectively). However, the survival rate ranging from 98.07 ± 0.10% to 98.93 ± 0.19%, hatchability of 97.93 ± 0.01% and the life-cycle of D. gallinae (9 days) was not affected by the lighting period.

CONCLUSIONS

Our findings demonstrated that prolonged darkness significantly promoted the proliferation levels of D. gallinae, resulting in increased number of mites and eggs in the rearing system. The promoted population growth of D. gallinae was found to be related to the increased feeding rate, engorgement level and oviposition level of mites under prolonged darkness. The egg hatchability, the survival rates and the duration of life-cycle of D. gallinae were not affected by the light regimes.

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.

Population characteristics of Macrocheles glaber (Acari: Macrochelidae) and Stratiolaelaps scimitus (Acari: Laelapidae) reared on a mushroom fly Coboldia fuscipes (Diptera: Scatopsidae)

Subterranean predatory mites are important biological control agents of pests in soil. In order to understand the population characteristics of two predatory mites, Macrocheles glaber Müller and Stratiolaelaps scimitus Womersley, we studied their development, survival and fecundity data under laboratory conditions using Coboldia fuscipes Meigen as a food source and analyzed them with the age-stage, two-sex life table. Macrocheles glaber had a significantly shorter developmental time, oviposition period, longevity and lower fecundity than those of S. scimitus. The intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R₀ ), net predation rate (C₀ ), and finite predation rate (ω) of M. glaber were significantly lower than those of S. scimitus. Both population parameters and computer simulation implied that S. scimitus is a potential powerful biocontrol agent compared to M. glaber.

Multigenerational exposure of populations of Oppia nitens to zinc under pulse and continuous exposure scenarios

Current soil remediation guidelines for metals reflect single-generation laboratory studies, but in the field, organisms are exposed to metals for more than one generation. The present study assessed the multigenerational effect of zinc (Zn) on Oppia nitens under a pulse or continuous exposure scenario. Synchronized adult mites (parents) were exposed to 6 concentrations of Zn in a field soil. For the pulse exposure, juveniles of parent mites from 3 of the 6 concentrations (105, 158, 237, 335, 553, and 800 mg/kg) were kept in clean media and reared until the third generation. At every generation, the sensitivity of the mites to Zn was tested in a dose-response manner. For the continuous exposure, the mites produced from the parents were re-exposed to the same concentration as their parents. According to critical-level estimates like the median effect concentration, all populations of the F2 and F3 generation mites in the pulse exposure were less sensitive to Zn than the parents and were protected at 250 mg/kg of Zn (Canadian Council of Ministers of the Environment [2018] soil quality guideline). However, the mite generations of the continuous exposure remained as sensitive as the parent generation and were not protected by the Zn guideline level. The Zn niche width narrowed considerably for all continuously exposed mite populations, indicating that they were more sensitive than the parent. Our results show that Zn has a deleterious multigenerational effect on continuously exposed populations of mites. Environ Toxicol Chem 2019;38:896-904. © 2019 SETAC.

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.

Demographic characteristics and population projection of Phytonemus pallidus fragariae reared on different strawberry cultivars

The strawberry mite, Phytonemus pallidus fragariae (Banks) (Acari: Tarsonemidae), is one of the most important pests of greenhouse grown strawberry plants. Field grown strawberries may also be infested by the pest in high humid conditions. Life tables give the most comprehensive description of the development, survival, stage differentiation, reproduction and consequently population growth of a population, and thus it is an important base of population ecology and pest management. In this study, to provide a comprehensive evaluation of an ecology-based and cost-effective control program, life history and demographic parameters of the strawberry mite were studied. The experiment was conducted under laboratory conditions providing 20 ± 1 °C, 80 ± 10% RH and L16:D8 photoperiod. The data were analyzed based on the age-stage, two-sex life table theory. The population parameters net reproduction rate (R₀ = 6.14 offspring), intrinsic rate of increase (r = 0.1317 day^-1), and finite rate of increase (λ = 1.1407 day^-1) on cv. Aromas were lower than those on the other cultivars tested. Based on the population characteristics, Aromas is a less favorable cultivar for the population growth of strawberry mite.

Seasonal dynamics and changing sea level as determinants of the community and trophic structure of oribatid mites in a salt marsh of the Wadden Sea

Global change processes affect seasonal dynamics of salt marshes and thereby their plant and animal communities. However, these changes have been little investigated for microarthropod communities. We studied the effect of seasonality and changes in sea level on oribatid mites in the natural salt marsh and on artificial islands in the back-barrier environment of the island Spiekeroog (Wadden Sea, Germany). Three zones of the artificial islands were filled with transplanted sods from the lower salt marsh zone and thereby exposed to three different inundation frequencies. We hypothesized that oribatid mite communities will differ along the natural salt marsh vegetation zones [upper salt marsh (USM), lower salt marsh (LSM), pioneer zone (PZ)], which are influenced by different tidal regimes. Accordingly, total oribatid mite densities declined from the USM and LSM to the PZ. Similarly, oribatid mite species compositions changed along the salt marsh transect and also responded to variations in inundation frequency in LSM on artificial islands with typical species of the USM, LSM and PZ being Multioppia neglecta (USM), Hermannia pulchella (LSM), Zachvatkinibates quadrivertex (LSM, PZ) and Ameronothrus schneideri (LSM, PZ). Oribatid mite density in the salt marsh and on the artificial islands was at a maximum in winter and spring; this was due in part to high density of juveniles, pointing to two reproductive periods. We hypothesized that oribatid mite trophic structure changes due to variations in abiotic (e.g., tidal dynamics, temperature) and biotic conditions (e.g., resource availability). Stable isotope (15N, 13C) and neutral lipid fatty acid analyses indicated that oribatid mite species have different diets with e.g., Z. quadrivertex feeding on macroalgae and fungi, A. schneideri feeding on microalgae and bacteria, and Scheloribates laevigatus and M. neglecta feeding on dead organic matter, bacteria and fungi. Overall, the results indicate that oribatid mite species in salt marshes are affected by changes in environmental factors such as inundation intensity, with the effects being most pronounced in species with narrow trophic niches and limited niche plasticity. The results also indicate that oribatid mite communities of the LSM respond little to short-term (one year) changes in inundation frequency.

Plant-mediated competition facilitates a phoretic association between a gall mite and a psyllid vector

Phoretic associations between mites and insects commonly occur in patchy and ephemeral habitats. As plants provide stable habitats for herbivores, herbivorous mites are rarely dependent on other animals for phoretic dispersal. However, a phoretic gall mite, Aceria pallida, which is found on plants, seasonally attaches to a herbivorous insect, Bactericera gobica, for overwintering survival. After detachment, the gall mite shares a habitat with its vector and is likely to compete with this vector for plant resources. However, excessive competition works against the sustainability of the seasonal phoretic association. How the gall mite, as an obligate phoretic mite, balances this relationship with its vector during the growing season to achieve phoresy is unknown. Here, the plant-mediated interspecific interaction between the gall mite and the psyllid after detachment was studied in the laboratory and field. The laboratory results showed that infestation by the gall mite had detrimental effects on the survival and development of psyllid nymphs. Meanwhile, the mite population and the gall size were also adversely affected. The results from the field showed that the mean densities of the mite galls and psyllids were lower in the mixed-species infestation treatment than in the single-species infestation treatment across the investigation period. However, the interspecific interaction between the gall mite and the psyllid decreased rather than accelerated leaf abscission caused by the psyllid, which promoted the persistence of the psyllid population and then indirectly contributed to phoretic association. Our results suggest that the plant-mediated competition between the phoretic gall mite and its vector after detachment facilitates the maintenance of the phoretic association.

A cryptic diapause strategy in Halotydeus destructor (Tucker) (Trombidiformes: Penthaleidae) induced by multiple cues

BACKGROUND

The polyphagous mite pest, Halotydeus destructor, typically has three generations during the cool moist season in Australia and produces over-summering diapause eggs in spring. Diapause eggs have a distinct thick and dark chorion and can survive heat, desiccation and the application of pesticides. Farmers suppress mites producing diapause eggs by a carefully timed spring pesticide application using Timerite^® , which predicts the onset of diapause egg production based largely on day length. We investigated the association between diapause induction and other environmental factors that may complicate diapause predictions.

RESULTS

Diapause in H. destructor induction was influenced by three interacting environmental factors, namely day length, temperature and soil moisture. A cryptic type of diapause egg that lacked a thick chorion and was instead morphologically similar to non-diapause eggs was also discovered. Like diapause eggs, this newly discovered egg type could also survive hot and dry summer conditions.

CONCLUSIONS

There is an opportunity to refine the Timerite^® spring spray by incorporating knowledge of other environmental factors inducing diapause in H. destructor. Compared with typical diapause eggs, the production of cryptic diapause eggs could reflect a strategy to deal with diversifying environmental stresses and/or represent a bet-hedging strategy to adapt to unpredictable environments. © 2018 Society of Chemical Industry.

Role of kin recognition in oviposition preference and cannibalism by the predatory mite Gynaeseius liturivorus

Animals often select oviposition sites to minimize the predation risk for eggs and juveniles, which are more vulnerable to predation than adults. When females produce eggs in clusters, the eggs and juveniles are likely to suffer from cannibalism. Although cannibalism among siblings is known to be lower than among non-siblings, there have been few investigations into the possibility that females select oviposition sites that reduce the risk of cannibalism for the offspring. To test this possibility, we examined oviposition preference by adult females of the predatory mite Gynaeseius liturivorus in response to the presence of her own eggs and to eggs of other females, offering plastic discs as oviposition substrates. Although females did not clearly show a preference for plastic discs on which they had oviposited, they avoided plastic discs on which other females had oviposited. When eggs of other females were artificially placed on clean plastic discs, adult female mites avoided these discs, suggesting that the eggs were used as cues for oviposition preference. Cannibalism among juvenile siblings was lower than among non-siblings. These observations show that adult females and juveniles of G. liturivorus discriminate kin relationships among conspecific individuals. Therefore, oviposition preference by adult female G. liturivorus may lead to the reduced risk of cannibalism among offspring.

Webbing life type and behavioral response of the date palm mite, Oligonychus afrasiaticus, to webbing residues on leaves and fruits of date palm

The present study examined the webbing life type and behavioral response of date palm mite (DPM) Oligonychus afrasiaticus (McGregor) toward its webbing residues, in presence or absence of immature individuals, on leaves and fruits of date palm. DPM exhibited a complicated web life type on both the leaves and fruits of date palm, which is characterized by the following features: complicated irregular web structure; webbing density on the leaves is medium and on the fruits extremely high; eggs are always laid on the threads of web without web cover; fecal pellets are deposited on the substrate surface (both leaf and fruit); quiescent stages are on the silken web threads; and the preferred site for feeding and walking is under the web. Behavioral observation of DPM females revealed that the midrib of leaves and the base of fruits of date palm were the preferred sites for feeding and web construction. The number and development stage of DPM affected the behavioral response of females on date palm leaves but not on the fruits. DPM spent most time feeding under the web on both the leaves and fruits of date palm.

The status of Demodex cornei: description of the species and developmental stages, and data on demodecid mites in the domestic dog Canis lupus familiaris

Demodecosis canina is one of the most important dog parasitoses, but its aetiology is still not well known. There are currently two known species of demodecid mite specific to the domestic dog Canis lupus familiaris Linnaeus, 1758 (Carnivora: Canidae). These are Demodex canis Leydig, 1859 (Acariformes: Demodecidae) and Demodex injai Desch & Hillier, 2003. There have also been many reports of the so-called 'short form', considered to be a separate species functioning under the name Demodex cornei nomen nudum, for which, however, no formal valid description has been documented. Taxonomic analysis of short forms of dog demodecid mites, associated with the stratum corneum, was performed, in line with the taxonomic criteria of Demodecidae systematics. This form was found to be a distinct species with features that differ from those of the other known species of this family. The species, including the adult and immature stages, is described. It is likely that different Demodex species parasitizing the domestic dog may be responsible for differentiated symptoms and different courses of demodecosis. However, the basis for clarifying this issue should be the correct, unambiguous identification of the species causing parasitosis.

Water mite (Acari: Hydrachnidia) diversity and distribution in undisturbed Dinaric karst springs

Large undisturbed karst springs in the Dinaric region are particularly interesting and extremely valuable and rare ecosystems, housing diverse and yet undiscovered water mite species. The complex life history traits of water mites include several life stages that are interconnected with other freshwater arthropod groups, making them important components of freshwater fauna. This study examined whether the differences in water mite assemblages between Mediterranean and alpine karst springs were driven by seasonal and/or regional changes in environmental conditions. The first ecological data on water mite dynamics and distribution in the Dinaric region of Croatia are presented. Water mites were represented by 11 taxa, decreasing in taxon richness from alpine to Mediterranean springs. Spatial patterns of water mite assemblages at the regional scale were best explained by water temperature, dissolved oxygen and water velocity. Pseudotorrenticola rhynchota and Oxus setosus were exclusively found in springs with higher water temperature and velocity, whereas the genera Aturus sp. and Woolastookia rotundifrons were exclusively recorded in the alpine springs, where oxygen concentrations were significantly higher. Atractides sp., Lebertia sp. and Sperchon sp. were recorded in most springs. Water mite abundances had a summer peak in the Mediterranean region, whereas two smaller peaks were observed in the spring and fall in the alpine region. Regional differences in the seasonality of water mite abundance were most likely patterned by the emergence of insect crenofauna.

Cryptic diversity within grass-associated Abacarus species complex (Acariformes: Eriophyidae), with the description of a new species, Abacarus plumiger n. sp

Accurate estimation of species richness is often complex as genetic divergence is not always accompanied by appreciable morphological differentiation. In consequence, cryptic lineages or species evolve. Cryptic speciation is common especially in taxa characterized by small and simplified bodies, what makes their proper identification challenging. The cereal rust mite, Abacarus hystrix, was regarded for a long time as a species associated with a wide range of grass hosts, whereas wide host ranges are rather rare in eriophyoid mites. Therefore, the generalist status of A. hystrix was questioned. In this paper we demonstrate that the diversity within Abacarus species associated with grasses is more complex than it was previously thought. The 78 Abacarus mtDNA COI sequences used in this study formed 10 highly supported clades (bootstrap value 99%) and four more distinct genetic lineages were represented by unique sequences. The genetic distances between them ranged from 6.6 to 26.5%. Moreover, morphological study and genetic approach based on the combination of the Poisson Tree Processes model for species delimitation (PTP) and a Bayesian implementation of PTP (bPTP), and Neighbour Joining analyses led to delimitation of a new species within the Abacarus complex: Abacarus plumiger, specialized on smooth brome (Bromus inermis). Furthermore, our analyses demonstrated a pattern of host-associated differentiation within the complex. Overall, our study indicates that cryptic speciation occurs in the grass-associated Abacarus genus, and suggests the need for more extensive sampling using integrative methods.

Development and Reproduction of Neoseiulus californicus (Acari: Phytoseiidae) and Tetranychus urticae (Acari: Tetranychidae) Under Simulated Natural Temperature

Although laboratory observations provide basic knowledge of the development and reproduction of predacious and phytophagous mites, little is known of their behavior under natural conditions. Using a closed system designed to simulate natural climate patterns, we investigated the development and reproduction of the predatory mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) and the pest mite Tetranychus urticae Koch (Acari: Tetranychidae) at air temperatures typical of June to October at three latitudes (Aomori, Tottori, and Naha) in Japan. The peaks of development in both species showed similar trends at each location. The shortest developmental times for both species were observed during August in Aomori, from July to September in Tottori and during August and September in Naha. Development of T. urticae was not completed during October in Aomori due to the decreased air temperature. High reproduction (number of eggs produced during 5 d from the first oviposition) of N. californicus was attained at the conditions that shortened the developmental times (i.e., high-temperature months). T. urticae showed a reproduction trend similar to that of N. californicus except for the low number of eggs produced during August in Naha due to the high mortality of adult females and during October in Tottori due to diapause incidence. This information is in agreement with field observations and together might be useful for planning biological control programs for phytophagous mites and for successful establishment of predacious mites in new habitats.

Food Suitability and Population Dynamics of Lorryia formosa (Acari: Tydeidae)

Lorryia formosa Cooreman (Acari: Tydeidae) is a species of mite commonly associated with citrus in many countries including the United States. A survey report in 1957 suggested phytophagous nature, while other studies claimed that L. formosa populations are associated with honeydew producing insects and sooty mold and it acts as a sanitizing agent. We investigated the effect of various diets on the survival and progeny production of L. formosa on excised leaves and the survival and potential to cause feeding damage to leaves of potted plants in a greenhouse study. A 2-yr field survey of a mandarin orchard was also conducted to elucidate the seasonal infestation, damage potential and population structure of L. formosa in a natural habitat. Results showed that all L. formosa adults and immatures died in less than 14 d on excised leaves, did not survive beyond 7 d on potted citrus plants alone, and caused no observable feeding damage to leaves or fruit. When sugar water, honeydew, or cottony cushion scale, Icerya purchasi Maskell (Hemiptera: Margarodidae), was present, adults and immatures survived the duration of the experiments and produced additional generations. The field survey showed that all stages of L. formosa were present in a mandarin orchard throughout the year and insecticide applications affected but did not eliminate mite populations. Fruit generally had a greater percentage infestation of mites (44.8 ± 4.0) than leaves (16.0 ± 4.7). These studies confirmed that L. formosa cannot sustain a population on leaf tissue alone and is nondamaging to citrus in California.

Combined Use of Predatory Mirids With Amblyseius swirskii (Acari: Phytoseiidae) to Enhance Pest Management in Sweet Pepper

The combined release of Orius laevigatus (Fieber) (Hemiptera: Anthocoridae) with Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) provides effective control of sweet pepper key pests, such as thrips and whiteflies. However, the management of the aphids can still be improved. Recently, the predatory mirids Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) and Macrolophus pygmaeus (Rambur) (Hemiptera: Miridae) have been found to be effective in the control of aphids, thrips and whiteflies when tested alone. Hence, integrating one of these two mirids with A. swirskii might enhance sweet pepper pest management. In this work, we began by investigating the co-occurrence of both mirid species when released together with A. swirskii. This was compared to the standard release of O. laevigatus with A. swirskii. N. tenuis and A. swirskii were involved in a bidirectional intraguild predation (IGP). On the contrary, this interaction (IGP) was apparently unidirectional in the case of M. pygmaeus with A. swirskii and O. laevigatus with A. swirskii. Both, M. pygmaeus and O. laevigatus significantly reduced the abundance of A. swirskii. Secondly, in a greenhouse experiment, where the same release combinations were tested (either N. tenuis, M. pygmaeus or O. laevigatus combined with A. swirskii), IGP seemed to be neutralized. Mirids with A. swirskii significantly suppressed thrips, whitefly, and aphid infestations. Contrarily, the combined use of O. laevigatus with A. swirskii did not reached a satisfactory control for aphids, despite the reduction in thrips and whitefly densities. Therefore, our results suggest that the use of mirids combined with A. swirskii could result in more efficient and robust biological control programs in sweet pepper crops.

Suitability of edaphic arthropods as prey for Proctolaelaps bickleyi and Cosmolaelaps brevistilis (Acari: Mesostigmata: Melicharidae, Laelapidae) under laboratory conditions

Soils are often complex habitats inhabited by a wide range of organisms, some harmful to plants and others beneficial, for example by attacking harmful organisms. Beneficial organisms include predatory mites, some of which have been commercialized for biological control of pest insects and mites. The objective of this work was to evaluate under laboratory condition the suitability of representative soil insect and mite pests, especially Aceria tulipae (Keifer), as prey to the soil-inhabiting predatory mites Proctolaelaps bickleyi (Bram) and Cosmolaelaps brevistilis (Karg). Predation, oviposition and survivorship of recently molted adult females of the predators were assessed in the dark in rearing chambers at 25 ± 1 °C and 75 ± 3% RH. Predation rate by P. bickleyi on A. tulipae was significantly higher than that by C. brevistilis (196.3 vs. 71.0 specimens/day). About 482 A. tulipae were preyed by each P. bickleyi at each day, when 500 A. tulipae were made available daily to the predator. Oviposition rate on that prey was also higher for P. bickleyi (4.2 eggs/day). For C. brevistilis, the highest level of oviposition was on Caliothrips phaseoli (Hood) (1.2 eggs/day). Survivorship was always higher for C. brevistilis (≥ 70%), given its ability to remain alive relatively long even in the absence of prey. High rates of survivorship of P. bickleyi were observed on A. tulipae, Bradysia matogrossensis (Lane) and Protorhabditis sp. Promising results were obtained for P. bickleyi on A. tulipae and even on other prey, justifying the conduction of complementary studies under field condition.

Influence of temperature and light-dark cycle on hatching of Eylais extendens

Little research has been done on egg diapause and the embryonic development of water mites. The aim of this study was to check the impact of temperature and periods of light on hatching of larvae of Eylais extendens. Three batches of eggs which were spawned on 30 July were placed at one of three temperatures (4, 10 and 20 °C) and two periods of light (7 and 14 h per day). Egg hatching (both, percentage of hatched larvae and rate of hatching) was found to differ between 4 versus 10 °C and between 4 versus 20 °C, but not between 10 versus 20 °C. The periods of light had no influence on hatching. This synchronization of hatching, enabling the eggs to emerge from diapause in the spring, could be considered an evolutionary adaptation aimed at postponing hatching of late-spawned eggs until a time allowing for completion of the full development cycle, including the parasitic larval stage.

Gender-specific differences in cannibalism between a laboratory strain and a field strain of a predatory mite

Many phytoseiid species, including Phytoseiulus persimilis, are known to engage in cannibalism when food is scarce and when there is no possibility to disperse. In nature adult females of P. persimilis are known to disperse when prey is locally depleted. Males, in contrast, are expected to stay and wait for potential mates to mature. During this phase, males can obtain food by cannibalizing. Therefore, we hypothesize that male P. persimilis exhibit a higher tendency to cannibalize than females. Because rearing conditions in the laboratory usually prevent dispersal, prolonged culturing may also affect cannibalistic behavior. We hypothesize that this should especially affect cannibalism by females, because they consume far more food. We tested these hypotheses by comparing males and females from two strains, one of which had been in culture for over 20 years, whereas the other was recently collected from the field. It is known that this predator can discriminate between kin and non-kin and prefers cannibalizing the latter, hence to construct lines with high relatedness we created isofemale lines of these two original strains. We subsequently tested to what extent the adult females and males of the original strains and the isofemale lines cannibalized conspecific larvae from the same strain/line in a closed system. Relatedness with the victims did not affect cannibalistic behavior, but males engaged more often in cannibalism than females, and females of the laboratory strain engaged more in cannibalism than those of the field strain, both in agreement with our ideas. We hypothesize that the difference in cannibalism between the two genders will increase when they have the alternative to disperse.

Redescription of Periglischrus herrerai (Acari: Spinturnicidae) Associated to Desmodus rotundus (Chiroptera: Phyllostomidae: Desmodontinae), With a Description of Adult Female Heteromorphism and an Analysis of its Variability Throughout the Neotropics

A redescription, with a discussion of new features and illustrations, for all life stages is presented for the parasitic mite Periglischrus herrerai Machado-Allison associated with the common vampire bat Desmodus rotundus (Geoffoy), including a description of the heteromorphic female and the first description of its female deutonymph. In addition, the morphological variation of P. herrerai is evaluated by morphometric analysis of the adults, concluding that there is an evident geographic variation throughout the neotropics. This study was possible by using type material of P. herrerai from the Machado-Allison collection, and voucher specimens from other collections, and specimens from an extensive surveying of hematophagous bats in some localities of the Pacific and Atlantic versants, and central Mexico.

Ricoseius loxocheles (Acari: Phytoseiidae) is not a predator of false spider mite on coffee crops: What does it eat?

Ricoseius loxocheles (De Leon) (Acari: Phytoseiidae) is often found in coffee crops and is known to feed on coffee leaf rust, Hemileia vastatrix Berkeley and Broome (Uredinales). As the occurrence of coffee leaf rust is limited primarily to the rainy season, the mite may use other food sources to survive during the periods of low pathogen prevalence. It is well known that phytoseiid mites can survive on a variety of food sources, such as herbivorous mites, fungi and pollen. We evaluated the ability of R. loxocheles to survive and reproduce on a diet of Brevipalpus phoenicis Geijskes (Acari: Tenuipalpidae), cattail pollen (Typha spp.), clover rust (Puccinia oxalidis), bee pollen (Santa Bárbara^® dehydrated pollen, Santa Bárbara, MG, Brazil) and coffee leaf rust. Ricoseius loxocheles did not survive or reproduce on any B. phoenicis stages tested (egg, larva, adult). The survival and oviposition of R. loxocheles were directly affected by the presence of coffee rust urediniospores, but not by the presence of the prey. Survival and oviposition of the phytoseiid were similar when fed cattail pollen, clover rust and coffee leaf rust but was lower when fed bee pollen. Our results show that R. loxocheles is not a predator of B. phoenicis but it is able to utilize other resources besides coffee leaf rust.

External morphology of the mouthparts and observations on behavior of Tuckerella japonica on Camellia sinensis in the continental USA

Tuckerella japonica Ehara (Acari: Tetranychoidea: Tuckerellidae) was found on stems of seedling plants of Camellia sinensis (L.) O. Kuntze (Theaceae) in the continental USA. This mite is able to pierce exposed green periderm tissue with its paired stylets on 1- to 3- or 4-year-old stems where the outer bark had split longitudinally. The mite was not found on branches older than 3 or 4 years, where splitting diminished and, eventually, a uniform covering of bark was formed. The mouthparts of T. japonica were examined under scanning electron microscopy and their external morphology was compared with known Tetranychoidea. There were usually one or two feeding holes in an area where the female subsequently deposited one or more eggs. Females were observed defending the areas where their eggs and/or young occurred. This behavior along with potentially limited access to exposed periderm or availability of shoots in the rows of plants may restrict higher populations of T. japonica from becoming established. The potential of T. japonica as an economic pest remains unknown at this time.

Comparison of Microbiomes between Red Poultry Mite Populations (Dermanyssus gallinae): Predominance of Bartonella-like Bacteria

Blood feeding red poultry mites (RPM) serve as vectors of pathogenic bacteria and viruses among vertebrate hosts including wild birds, poultry hens, mammals, and humans. The microbiome of RPM has not yet been studied by high-throughput sequencing. RPM eggs, larvae, and engorged adult/nymph samples obtained in four poultry houses in Czechia were used for microbiome analyses by Illumina amplicon sequencing of the 16S ribosomal RNA (rRNA) gene V4 region. A laboratory RPM population was used as positive control for transcriptome analysis by pyrosequencing with identification of sequences originating from bacteria. The samples of engorged adult/nymph stages had 100-fold more copies of 16S rRNA gene copies than the samples of eggs and larvae. The microbiome composition showed differences among the four poultry houses and among observed developmental stadia. In the adults' microbiome 10 OTUs comprised 90 to 99% of all sequences. Bartonella-like bacteria covered between 30 and 70% of sequences in RPM microbiome and 25% bacterial sequences in transcriptome. The phylogenetic analyses of 16S rRNA gene sequences revealed two distinct groups of Bartonella-like bacteria forming sister groups: (i) symbionts of ants; (ii) Bartonella genus. Cardinium, Wolbachia, and Rickettsiella sp. were found in the microbiomes of all tested stadia, while Spiroplasma eriocheiris and Wolbachia were identified in the laboratory RPM transcriptome. The microbiomes from eggs, larvae, and engorged adults/nymphs differed. Bartonella-like symbionts were found in all stadia and sampling sites. Bartonella-like bacteria was the most diversified group within the RPM microbiome. The presence of identified putative pathogenic bacteria is relevant with respect to human and animal health issues while the identification of symbiontic bacteria can lead to new control methods targeting them to destabilize the arthropod host.

Morpho-functional variety of the coxal glands in cheyletoid mites (Prostigmata). II. Cheyletidae

Trombidiform mites are characterized by the presence of several paired glands in the anterior body portion united by a common conducting duct (podocephalic canal). Apart from the acinous (salivary) glands the podocephalic system includes a pair of tubular coxal glands (CGs) responsible for osmoregulation. The aim of the present study was to figure out how functional changes of acinous glands reflect on the corresponding CG. For this purpose, the anatomy and fine structure of the CG were analyzed in two mite species, Bakericheyla chanayi and Ornithocheyletia sp. (Cheyletidae), which have a different composition of their single acinous gland. The results showed that in both species the CG lacks a filtering saccule. It is composed of the proximal and distal tubes and leads into a cuticle-lined excretory duct. Both tubes demonstrate a similar species-specific fine structure. They are characterized by an extensive system of apical membrane invaginations (internal canals) associated with numerous large mitochondria. Local areas of modified internal canals were regularly observed in both species. They contain structures resembling those constituting filtering slit diaphragms of other animals. In O. sp., CG cells in addition demonstrate features characteristic of protein-like secretion. Apparently this correlates with the loss of true salivary glands in this species, as its acinous gland was previously assumed as silk producing. Contrary to this, the CG of B. chanayi shows no kind of granulation, which coincides with the presence of a salivary portion in its complex acinous gland. The microtubule-rich intercalary cells at the base of the excretory duct were associated with special muscles presumably regulating the dilation of the duct lumen. These cells might represent a basic feature common to different types of podocephalic glands.

Biological control of Echinothrips americanus by phytoseiid predatory mites and the effect of pollen as supplemental food

The poinsettia thrips, Echinothrips americanus Morgan, is an upcoming pest in greenhouse crops, causing serious damage in various vegetable and ornamental crops through extensive foliage feeding. We assessed which stages of E. americanus are attacked and killed by the phytoseiid predatory mites Amblyseius swirskii (Athias-Henriot), Amblydromalus limonicus (Garman and McGregor), Euseius gallicus Kreiter and Tixier and Euseius ovalis (Evans). Both the predation and oviposition rates were assessed in the laboratory to evaluate which mite species is potentially the most effective predator of E. americanus. In two greenhouse trials with non-flowering sweet pepper plants, we compared the efficacy of the predators E. gallicus and E. ovalis with A. swirskii and we assessed how this was affected by the application of cattail pollen. All stages of E. americanus, except adults, were consumed by all species of predatory mites. The highest predation and oviposition rates were recorded for A. limonicus followed by A. swirskii and E. ovalis when first and second larval stages were provided as prey, but E. ovalis appeared to be the best predator of thrips pupae. Euseius gallicus displayed very low predation and oviposition rates compared to the other species of predatory mites. Cattail pollen did not support the population growth of poinsettia thrips, but it strongly increased the predatory mite population densities, particularly those of E. ovalis. Both A. swirskii and E. ovalis significantly reduced thrips densities on plants. The application of pollen significantly enhanced the control of E. americanus by A. swirskii; this was not the case for E. ovalis. Euseius gallicus did not reduce densities of E. americanus on sweet pepper plants, not even at high densities in the presence of pollen.

Lethal and sublethal effects of pesticides in the management of Polyphagotarsonemus latus (Banks) (Acari: Tarsonemidae) on Capsicum annuum L

BACKGROUND

The evaluation of lethal and sublethal effects is of great importance for a complete assessment of the total impact of chemical compounds upon pest populations and the development of management strategies. In this study, we evaluated the lethal and sublethal effects of different synthetic and botanical products on the broad mite Polyphagotarsonemus latus (Banks), a major pest of Capsicum annuum L. and other crops.

RESULTS

Abamectin had the highest lethal effect on P. latus, followed by spiromesifen, azadirachtin, neem oil and nitrogen fertiliser + citric acid. The sublethal effects of the products were indicated by the influence on mite population growth, affecting the numbers of females, males, larvae, pupae and eggs. Furthermore, a negative instantaneous rate of increase in P. latus and repellent effects were observed.

CONCLUSION

The lethal and sublethal effects of abamectin, spiromesifen, azadirachtin and neem oil significantly affect P. latus population growth, as well as causing repellence to this mite on C. annuum, and they should be considered in the integrated pest management of this mite. © 2017 Society of Chemical Industry.

Quantitative Analysis of Long-Term Mass Rearing of Neoseiulus californicus (Acari: Phytoseiidae) on Almond Pollen

Long-term feeding effects of the almond pollen on the life table parameters of Neoseiulus californicus McGregor were assessed after 5, 10, and 20 generations after introduction in the rearing arena. Furthermore, to evaluate behavioral characteristics of the mass-reared predator (strain A) in face with the real prey, functional and numerical responses of the predator to different densities of the twospotted spider mite nymphs were determined, and the obtained data were compared with those reared on twospotted spider mite (strain T). Long-term rearing did not significantly affect total fecundity of N. californicus (ranged from 37.79 to 41.91 eggs). Nevertheless, preadult duration in the 5th generation was significantly longer than the 10th and 20th generations. The intrinsic rate of increase (r) in the 10th (0.2056 d-1) and 20th (0.2201 d-1) generations had not significant difference together. However, the r value slightly dropped in the 5th generation (0.1706 d-1) because of the irregular offering of fresh pollen to the rearing colonies before that. Both strains of N. californicus exhibited a type II functional response; however, the N. californicus reared on the almond pollen (strain A) had a higher attack rate (a) and shorter handling time (Th). The individuals reared on the almond pollen had a greater size than those reared on twospotted spider mite; its higher predation potential is probably due to this characteristic. Consequently, the rearing of N. californicus on the almond pollen positively affected its attributes including high survivorship, body size, and fecundity, and subsequently higher potential to control twospotted spider mite.

Comparative stylostome ultrastructure of Hirsutiella zachvatkini (Trombiculidae) and Trombidium holosericeum (Trombidiidae) larvae

Stylostomes (feeding tubes) of Hirsutiella zachvatkini (Schluger) (Trombiculidae), feeding on bank voles [Myodes glareolus (Schreber)], and of Trombidium holosericeum (L.) (Trombidiidae), feeding on larvae of Stenodemini sp. (Heteroptera, Miridae), were studied by TEM methods and on semi-thin sections. The stylostome of H. zachvatkini is a homogeneous structure of low electron density and without strict margins. It extends within the concave host epidermis, undergoing hyperplasia and hyperkeratosis. TEM does not reveal any obvious stratification in the stylostome walls. The cheliceral movable digits are moved apart by 5-6 µm and tightly applied/adhered to the stylostome substance. A local area beneath the open end of the stylostome canal is not empty but contains a nearly homogeneous substrate, which can pass into the central stylostome canal. The latter is mostly free of contents. In contrast to H. zachvatkini, larvae of T. holosericeum form a root-like stylostome chaotically branching within the clear space underneath the host cuticle free of tissue elements. Tubules of the distal stylostome branches become progressively thinner and disappear blindly. As in H. zachvatkini, the stylostome walls of T. holosericeum are devoid of stratification but show moderate to high electron density. The cheliceral movable digits are moved apart by the same distance, as in H. zachvatkini, and tightly applied to the stylostome substance. The lumen of the central canal is either electron lucent, in the distal portions, or filled with a fine granular or homogeneous substrate of low electron density in the proximal portions forming a type of ampoule. This study shows that Trombiculidae and Trombidiidae share similar initial stages of stylostome formation but the resultant stylostome of each family is distinctly different.

Attempt to Develop Cost-Effective Rearing of Amblyseius swirskii (Acari: Phytoseiidae): Assessment of Different Artificial Diets

Commercial production of Amblyseius swirskii Athias-Henriot based on storage mites needs both space and labor to maintain large cultures of these prey, and also may lead to health problems for workers. Therefore, the accessibility of a suitable artificial diet could eliminate the mentioned problems; however, the artificial diets must support the persistent production of high quality progeny. This study endeavored to find a more easily available and cheaper nutrient that may further reduce the cost of diet production for A. swirskii. The predator's performance was determined when it was fed on a basic artificial diet (AD1) composed of honey, sucrose, tryptone, yeast extract, and hen egg yolk, and on eight other artificial diets consisting of 80% AD1 enriched with different nutrients including maize pollen (AD2), hemolymph of Plusia gamma L. (AD3), Ephestia eggs (AD4), Artemis cysts (AD5), Ephestia last-instar larvae (AD6), multivitamin syrup (AD7), bovine serum albumin (AD8), and bull sperm (AD9). The lowest development time was on AD2. The highest value of fecundity and oviposition period were observed on AD5, followed by AD2 and AD4. The intrinsic rate of increase (r) and the finite rate of increase (λ) reached the maximal value on AD5. Feeding on AD2 and AD5 resulted in highest value of R0 (net reproductive rate). Our results indicated that Artemia cysts and maize pollen had better potential to be used as nutrient in artificial diet for mass production of A. swirskii. Overall, it seems that AD2 is the most cost effective than others.

Temperature-Dependent Demography of Two Closely Related Predatory Mites Neoseiulus womersleyi and N. longispinosus (Acari: Phytoseiidae)

Temperature has significant effects on the development, survival, and reproduction of ectothermic organisms. In this study, we examined the effect of temperature on the demographic characteristics of two predatory mite species, Neosciulus womersleyi (Schicha) and N. longispinosus (Evans), reared on Tetranychus urticae Koch. The developmental and reproductive traits of both species were examined at 10 constant temperatures between 15 °C and 37.5 °C. The preadult development time of N. womersleyi and N. longispinosus decreased with increasing temperature until 32.5 °C and 35 °C, respectively. The lower developmental threshold (T0) and thermal constant (K) estimated by using a linear model were 11.61 °C and 69.36 DD for N. womersleyi and 11.92 °C and 61.5 DD for N. longispinosus, respectively. Total preoviposition period and total longevity of females and males of N. womersleyi and N. longispinosus decreased with increasing temperature. The mean generation time (T) first decreased with temperature until 32.5 and 35 °C for N. womersleyi and N. longispinosus, respectively, and then increased at higher temperatures. The R0 and r values first increased with temperature until 32.5 and 30 °C for N. womersleyi and N. longispinosus, respectively, and then decreased at higher temperatures. The R0 and r values for N. longispinosus at 37.5 °C were 0.3 offspring and -0.143 d-1, respectively. These results show that N. longispinosus is less fit than N. womersleyi at 37.5 °C.

Does Long-Term Feeding on Alternative Prey Affect the Biological Performance of Neoseiulus barkeri (Acari: Phytoseiidae) on the Target Spider Mites?

The predatory mite Neoseiulus barkeri (Hughes) is a good biological control agent for many small sucking pests. We aimed to determine whether rearing long term on alternative prey versus target prey species affected the performance of N. barkeri. Therefore, we investigated the prey preference, life tables, and population parameters of N. barkeri between alternative prey Tyrophagus putrescentiae (Schrank) and three species of spider mites, Tetranychus urticae Koch, Panonychus citri (McGregor), and Eotetranychus kankitus Ehara. We found that N. barkeri preferred the tetranychid mites to the alternative prey. Between the tetranychid mites, the predator consumed more P. citri and E. kankitus than T. urticae. When reared on T. urticae, the total developmental time and longevity of N. barkeri were the longest, whereas the intrinsic rate of increase was the lowest, indicating that the biotic fitness of predatory mite preyed on target of T. urticae was higher than on alternative prey of T. putrescentiae. However, total developmental time, longevity, and fecundity did not differ between N. barkeri reared on T. putrescentiae and P. citri, although these parameters were higher than those for mites reared on E. kankitus, indicating that the predatory mite reared on T. putrescentiae may not be affected to control P. citri, and that coexistence of P. citri and E. kankitus may enhance the control efficiency of N. barkeri. Altogether, our results demonstrated that long-term feeding on the alternative prey T. putrescentiae did not affect the performance of the predatory mite N. barkeri on various target spider mites.