Spider mite egg extract modifies Arabidopsis response to future infestations

Transcriptional plant responses are an important aspect of herbivore oviposition studies. However, most of our current knowledge is derived from studies using Lepidopteran models, where egg-laying and feeding are separate events in time. Little is known regarding plant response to pests where females feed and oviposit simultaneously. The present study characterized oviposition-induced transcriptomic response of Arabidopsis to Tetranychus urticae egg extracts. Transcriptional evidence indicates that early events in plant response to the egg extract involve responses typical to biotic stresses, which include the alteration in the levels of Ca2+ and ROS, the modification of pathways regulated by the phytohormones jasmonic acid and ethylene, and the production of volatiles and glucosinolates as defence mechanisms. These molecular changes affect female fertility, which was significantly reduced when mites fed on plants pre-exposed to the egg extract. However, longer periods of plant exposure to egg extract cause changes in the transcriptional response of the plant reveal a trend to a decrease in the activation of the defensive response. This alteration correlated with a shift at 72 h of exposition in the effect of the mite feeding. At that point, plants become more susceptible and suffer higher damage when challenged by the mite.

Biological attributes and qualitative damage of Oligonychus mangiferus (Rahman & Sapra) (Acariformes: Tetranychidae) on the medicinal plant Ichnocarpus frutescens (L.) W.T. Aiton

Oligonychus mangiferus (Rahman & Sapra) was found infesting the medicinal plant, Ichnocarpus frutescens L. Its biology and reproduction were studied at four different constant temperature conditions in the laboratory. O. mangiferus completed its development faster (7.10 to 8.77 days) at 30° - 32°C. Its egg-laying was highest at 20°C (31.03 eggs/female), but with similar progenial sex ratio ( :? ) (1:2.68 to 1:2.84) across different temperatures. At 25°C, Mean Generation Time (T) and Doubling Time (DT) were lowest 15.26 days and 8.95 days, respectively, while, Intrinsic Rate of Natural Increase (rm) was highest (0.085 female off-springs/female/day). Feeding damage by mangiferus resulted in apparent decline in chlorophyll and flavonoid contents, while alkaloid and terpenoid contents showed increase in mite infested leaves. Observed changes in the quantity of secondary metabolites like alkaloids, flavonoids and terpenoids, subsequent to mite feeding was significant, owing to the medicinal value of the herb. Further investigation on these biochemical changes may throw light on more advantageous medicinal use of Ichnocarpus for treating many human disorders.

A salivary chitinase of Varroa destructor influences host immunity and mite’s survival

Varroa destructor is an ectoparasite of honey bees and an active disease vector, which represents one of the most severe threats for the beekeeping industry. This parasitic mite feeds on the host’s body fluids through a wound in the cuticle, which allows food uptake by the mother mite and its progeny, offering a potential route of entrance for infecting microorganisms. Mite feeding is associated with saliva injection, whose role is still largely unknown. Here we try to fill this gap by identifying putative host regulation factors present in the saliva of V. destructor and performing a functional analysis for one of them, a chitinase (Vd-CHIsal) phylogenetically related to chitinases present in parasitic and predatory arthropods, which shows a specific and very high level of expression in the mite’s salivary glands. Vd-CHIsal is essential for effective mite feeding and survival, since it is apparently involved both in maintaining the feeding wound open and in preventing host infection by opportunistic pathogens. Our results show the important role in the modulation of mite-honey bee interactions exerted by a host regulation factor shared by different evolutionary lineages of parasitic arthropods. We predict that the functional characterization of Varroa sialome will provide new background knowledge on parasitism evolution in arthropods and the opportunity to develop new bioinspired strategies for mite control based on the disruption of their complex interactions with a living food source.

Evaluation of a ‘Preventative’ Strategy to Manage Spider Mites on Almond

Field experiments were conducted in two commercial almond orchards located in the southern San Joaquin Valley during 2016 and 2017 to evaluate a “preventative” strategy to manage spider mites. Pacific mite, Tetranychus pacificus McGregor, was identified as the only mite species infesting the experimental sites in both years. We monitored mites weekly in 3.6-hectare plots over approximately 21 weeks in 2016 and in 2017 using guidelines developed by the University of California. In late May, prior to the detection of mites, preventative acaricide treatments, abamectin, cyflumetofen, or etoxazole were applied to the experimental plots at a field rate. In 2016 and 2017, mite densities in all the treatments increased at early-July, peaked at mid-August, and were undetectable by late August. Preventative acaricide-treated plots in 2016 tended to have significantly lower mite densities than in the untreated control plots. Although in 2017, densities in the acaricide-treated plots tended to not significantly differ from control plots. Mite feeding injury, measured as mean cumulative mite-days, did not exceed the economic threshold during the experiment. The biological control agent, sixspotted thrips, Scolothrips sexmaculatus (Pergande) likely played a role in controlling mite populations at mid and late August. Our results indicate that a preventative strategy does not play a definitive role in T. pacificus management on almond. Additionally, acaricides with the active ingredient, abamectin, are heavily relied on as preventative treatments. We assessed populations of T. pacificus from the mid and southern San Joaquin Valley and found increased tolerance to a medium level of resistance to the acaricide.

The evaluation of feeding, mortality and oviposition of poultry red mite (Dermanyssus gallinae) on aging hens using a high welfare on-hen feeding device

A study was performed to examine any effect of hen age on the feeding ability and mortality of different life-stages of Dermanyssus gallinae [Poultry Red Mite (PRM)] when fed using a high welfare, on-hen mite feeding device. Mite feeding assays were carried out every two weeks on a cohort of five Lohman Brown hens with devices containing adult and deutonymph PRM or adult and protonymph PRM. Feeding rates and mortality of each PRM life stage and oviposition of adult female PRM were evaluated over an 18-week period. There was a significant reduction in oviposition rates of female PRM as they fed on hens of increasing age. However, no clear trend was detected between the feeding rates of all three haematophagous life stages and hen age. The same conclusion was reached regarding mite mortality post-feeding in both deutonymph and adult female PRMs, although a weak positive association was apparent between hen age and protonymph PRM mortality. This study shows that the on-hen feeding device can be used both for short term studies to assess novel anti-PRM products (new acaricides, vaccines etc.) and longer, longitudinal studies to determine longevity of the effects of such novel anti-PRM products. It also demonstrates that blood feeding by mites on older hens is less able to sustain PRM populations than feeding on younger hens. This on-hen mite feeding device directly impacts upon reduction and refinement by greatly reducing the numbers of birds required per experimental group compared to traditional PRM challenge infestation models and by eliminating the need for birds to be exposed to large numbers of mites for extended periods of time that can cause welfare concerns. This paper describes the methodology for these studies and how to assemble pouches and handle mites both before and after feeding assays.

An Improved Method for in Vitro Feeding of Dermanyssus Gallinae (Poultry Red Mite) Using Baudruche Membrane (Goldbeater’s Skin).

Background: Dermanyssus gallinae, or poultry red mite (PRM), is one of the most economically important ectoparasites in laying hens worldwide with infestations leading to both welfare and economic issues. Research into the testing and validation of novel vaccines and systemic acaricides to control PRM initially requires the use of in vitro methodologies before using in vivo assessments. In vitro methods to date have either involved PRM feeding on hen blood through biological membranes such as chick skin, which can be difficult to obtain and variable in quality, or through synthetic membranes that are unsatisfactory due to breakage and lack of natural feeding cues. The use of hen blood in these systems also requires multiple procedures (bleeds) to provide sufficient material for experimental replicates and the potential for using other species, from which larger blood volumes can be withdrawn in a single procedure (e.g. geese), could improve this technique as a refinement in the use of animals in research.Methods: Using adult female PRM, an initial experiment with an existing in vitro feeding device employing a Parafilm™ M membrane [1] was used to investigate any differences in mite feeding, egg laying and mortality when fed goose or hen blood. Subsequently, any effects on these parameters when PRM were fed through two different membranes; Parafilm™ M and Baudruche membrane, and a combination of these membranes with an overlaid polyester mesh to promote mite attachment, were then tested using goose blood as the food source.Results: PRM fed equally well on goose or hen blood through a Parafilm™ M membrane and there were no statistically significant differences in mortality of PRM fed with either blood type, although a significant increase (p = 0.03) in eggs laid per fed mite when using goose blood was demonstrated, indicating that goose blood is a satisfactory replacement for hens blood. A 70% increase in PRM feeding was observed when mites were fed on goose blood through a Baudruche membrane when compared to the Parafilm™ M membrane. Addition of an overlaid polyester mesh did not further improve feeding rates on either membrane. A significant increase (p = 0.04) in PRM egg laying was observed in mites fed on goose blood through Baudruche membrane, compared to those fed through Parafilm™ M. A mean of 1.22 eggs per fed mite was obtained using the Baudruche feeding device compared to only 0.87 eggs per fed mite using the Parafilm™ M device when neither had a polyester mesh overlay. It was noted that PRM feeding through Baudruche membrane had fed to repletion when compared to those fed through Parafilm™ M.Conclusion: The in vitro feeding of poultry red mite can be readily facilitated through the use of goose blood in feeding devices with Baudruche membrane.

Genome-Wide Analysis Reveals Transcription Factors Regulated by Spider-Mite Feeding in Cucumber (Cucumis sativus)

To gain insight into the regulatory networks that underlie the induced defense in cucumber against spider mites, genes encoding transcription factors (TFs) were identified in the cucumber (Cucumissativus) genome and their regulation by two-spotted spider mite (Tetranychusurticae) herbivory was analyzed using RNA-seq. Of the total 1212 annotated TF genes in the cucumber genome, 119 were differentially regulated upon spider-mite herbivory during a period of 3 days. These TF genes belong to different categories but the MYB, bHLH, AP2/ERF and WRKY families had the highest relative numbers of differentially expressed genes. Correlation analysis of the expression of TF genes with defense-associated genes during herbivory and pathogen infestation, and in different organs resulted in the putative identification of regulators of herbivore-induced terpenoid and green-leaf-volatile biosynthesis. Analysis of the cis-acting regulatory elements (CAREs) present in the promoter regions of the genes responsive to spider-mite feeding revealed potential TF regulators. This study describes the TF genes in cucumber that are potentially involved in the regulation of induced defense against herbivory by spider mites.

The predating activity and prey impact on life cycle and development of predatory mite (amblysieus swirskii)

Amblyseius swirskii is commonly used to control whitefly and thrips, twospotted spider mite(T.urticae) in greenhouse vegetables and some ornamental crops. This study in each of three different types(two spotted spider mite feeding , pollen feeding, thrips feeding) of feeding pray, 1 females were observed to die at relative humidity 35-60% and at temperatures of 25-300С, laboratory light:dark(16:8) and characteristics of the pray were studied in the development of fertility. We studied mite’s nutritional features, and hunting activities. Amblysieus swirskii’s egg development good establish 2.18±0.17 days in environment which is pollen feeding, 2.48±0.04 days in thrips feeding environment, 2.014±0.098 in two spotted spider mite feeding environment, Growth is until Larvae turned to Nymph there is a hole day in three environments, until Nymph turned to adult tick there are 3.13±0.23 days in pollen feeding environment, 3.25±0.29 days in thrips feeding environment, 2.014±0.098 two spotted spider mite prey environment. A Generation 6.3±0.3 day’s pollen feeding environment, 6.72±0.25 days in thrips feeding environment, 6.55±0.32 days in two spotted spider mite prey environment. Therefore conclusion is feeding environment doesn’t influence their life cycle. Research shows that adult antelope feeds with 15.2 two spotted spider mite, 5.1 thrips daily, decreasing it`s population. Having observed the females egg development in three different types of feeding environment it showed highest result, 14 days, at a temperature of 29.7 1.47C and 30 3.33% moisture environment. In contrast it showed its lowest result, 6 days, in dusty feeding environment whereas in environment with thrips it lay it`s eggs in 12 days for an average. Observing Amblysieus swirskii’s laying egg and lifespan, found out that they able to lay 13±2.6 eggs in two spotted spider mite provision environment, 13.6±2.08 days survive. In thrips feeding environment laying 6.3±0.5 eggs and survive 12.3±2.08 days, in pollen feeding environment laying 4±1 eggs, 7.6±0.5 days surviving. Ангуучин амблисейус (аmblysieus swirskii) хачгийн идэш тэжээлийн онцлог, үржил хөгжил, ангуучлах идэвхийг судалсан дүн Хураангуй: Ангуучин хачиг амблисейус (Аmblysieus swirskii)ийн үржил хөгжлийг лабораторийн гэрэл: харанхуй (16:8), 25-300С дулаантай, 35-60% чийгшилтэй орчинд ургамлын тоос, шүлхий хачиг, трипс гэсэн гурван идэш тэжээлийн хувилбартайгаар үржил хөгжил, ангуучлах идэвхийг судлав.Ангуучин хачиг амблисейус (Аmblysieus swirskii)-ийн өндөгний хөгжил ургамлын тоос идэштэй орчинд 2.18±0.17 хоног, трипс идэштэй орчинд 2.48±0.04 хоног, шүлхий хачиг идэштэй орчинд 2.014±0.098 хоног авгалдайнаас нимф болох шатанд гурван орчинд бүгд 1 хоног, нимфээс бие гүйцсэн ангуучин хачиг болох шатанд тоос идэштэй орчинд 3.13±0.23 хоног, трипс идэштэй орчинд 3.25±0.29 хоног, энгийн шүлхий хачиг идэштэй орчинд 2.014±0.098 хоног тус тус бойжсон бол 1 үе удам нь тоосоор хооллосон орчинд 6.3±0.3 хоног, трипсээр хооллосон орчинд 6.72±0.25 хоног, энгийн шүлхий хачгаар хооллосон орчинд 6.55±0.32 хоног тус тус үргэлжлэв. Ангуучин бие гүйцсэн амблисейус (Аmblysieus swirskii) хачгийн ангуучлах идэвхийг судлахад өдөрт 15.2 шүлхий хачиг, 5.1 трипс дунджаар идэж тоо, толгойг бууруулж байна. Эмэгчин хачгийн төлөрхөг чанарыг дээр дурьдсан гурван идэш тэжээлийн орчинд судлахад шүлхий хачиг идэш тэжээлийн орчинд хамгийн олон хоног өндөглөсөн буюу дунджаар 14 хоног, хамгийн цөөн хоног өндөглөсөн буюу тоостой идэш тэжээлийн орчинд дунджаар 6 хоног өндөглөсөн бол трипстэй идэш тэжээлийн орчинд дунджаар 12 хоногийн турш өндөглөлт үргэжилж байна. Ангуучин хачгийн өндөглөлт ба амьдрах хугацааг тогтооход энгийн шүлхий хачиг идэш тэжээлийн орчинд 13±2.6 өндөг төрүүлж, 13.6±2.08 хоног амьдарч, трипс идэш тэжээлийн орчинд 6.3±0.5 өндөг гаргаж 12.3±2.08 хоног амьдаржилж басан бол тоостой идэш тэжээлийн орчинд 4±1 өндөг гаргаж 7.6±0.5 хоног тус тус амьдарч байгааг тогтоов. Түлхүүр үг: Биологийн хамгаалал, ангуучлах идэвх, идэш тэжээлийн онцлог

Haemolymph removal by Varroa mite destabilizes the dynamical interaction between immune effectors and virus in bees, as predicted by Volterra's model

The association between the deformed wing virus and the parasitic mite Varroa destructor has been identified as a major cause of worldwide honeybee colony losses. The mite acts as a vector of the viral pathogen and can trigger its replication in infected bees. However, the mechanistic details underlying this tripartite interaction are still poorly defined, and, particularly, the causes of viral proliferation in mite-infested bees. Here, we develop and test a novel hypothesis that mite feeding destabilizes viral immune control through the removal of both virus and immune effectors, triggering uncontrolled viral replication. Our hypothesis is grounded on the predator–prey theory developed by Volterra, which predicts prey proliferation when both predators and preys are constantly removed from the system. Consistent with this hypothesis, we show that the experimental removal of increasing volumes of haemolymph from individual bees results in increasing viral densities. By contrast, we do not find consistent support for alternative proposed mechanisms of viral expansion via mite immune suppression or within-host viral evolution. Our results suggest that haemolymph removal plays an important role in the enhanced pathogen virulence observed in the presence of feeding Varroa mites. Overall, these results provide a new model for the mechanisms driving pathogen–parasite interactions in bees, which ultimately underpin honeybee health decline and colony losses.