Incidence of eriophyid mites (Acariformes: Eriophyidae) and predatory mites (Parasitiformes: Phytoseiidae) in Florida citrus orchards under three different pest management programs.

The abundance and diversity of eriophyid and phytoseiid mites in south and central Florida were assessed in six citrus orchards under three different pest management systems, conventional, organic, and untreated. Tree canopy, ground cover, and leaf litter were sampled every two months in two groves for each of the three pest management systems from April 2019 to February 2021. The citrus rust mite, Phyllocoptruta oleivora (Ashmead) represented 95 to 99% of the rust mites sampled in each grove except in one untreated orchard where it accounted for 45% of the samples (n = 938 total P. oleivora mounted specimens). The pink citrus rust mite, Aculops pelekassi (Keifer) was present in organic and untreated orchards at 5% and 28%, respectively, but absent from conventional orchards (n = 134 total A. pelekassi mounted specimens). Twenty-nine species of phytoseiid mites were identified from 1778 specimens. Thirteen species were present in the canopy, fifteen in the ground cover, and eighteen in the leaf litter with some common species among these habitats. In the tree canopy, Typhlodromalus peregrinus (39%), Euseius spp. (25%), and Iphiseiodes quadripilis (19%) were the dominant species. Typhlodromalus peregrinus (43%), Typhlodromips dentilis (25%), and Proprioseiopsis mexicanus (13%) were the major species in the ground cover. Species richness was lower in organic orchards (3.0) compared to conventional and untreated orchards (5.0 and 4.7, respectively). In the leaf litter, Amblyseius curiosus (26%), Proprioseiopsis carolinianus (15%), Chelaseius floridanus (14%), and Amblyseius tamatavensis (12%) were the most common species. Shannon index was significantly higher in conventional orchards (1.45) compared to organic and untreated orchards (1.02 and 1.05, respectively). Evenness was also higher in conventional orchards (0.86) compared to organic and untreated (0.72 and 0.68, respectively). Finding of several phytoseiids in abundance across pest management programs suggest the need for identifying their role in pest suppression particularly mites.

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.

Empirically tuned theory reveals why symbiont abundance 'mite' vary across hosts.

Research Highlight: del Mar Labrador, M., Serrano, D., Doña, J., Aguilera, E., Arroyo, J. L., Atiénzar, F., Barba, E., Bermejo, A., Blanco, G., Borràs, A., Calleja, J. A., Cantó, J. L., Cortés, V., de la Puente, J., de Palacio, D., Fernández-González, S., Figuerola, J., Frías, Ó., Fuertes-Marcos, B. Garamszegi, L. Z., Gordo, Ó., Gurpegui, M., Kovács, I., Martínez, J. L., Meléndez, L., Mestre, A., Møller, A. P., Monrós, J. S., Moreno-Opo, R., Navarro, C., Pap, P. L., Pérez-Tris, J., Piculo, R., Ponce, C., Proctor, H., Rodríguez, R., Sallent, Á., Senar, J., Tella, J. L., Vágási, C. I., Vögeli, M., & Jovani, R. (2023). Host space, not energy or symbiont size, constrains feather mite abundance across passerine bird species. Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.14032. Symbionts represent crucial links between species in ecosystems. Consequently, understanding their patterns of abundance is a major goal in the study of symbioses. However, multiple biotic and abiotic factors may regulate symbionts, and disentangling the mechanisms that drive variation in their abundance across host species is challenging. One promising strategy to approach this challenge is to incorporate biologically relevant data into theoretical models. In a recent study, Labrador et al. (2023) used this strategy to investigate the poorly understood symbiosis between feather mites and their avian hosts. They integrate a remarkable amount of empirical data with models based on the metabolic theory of ecology to determine what factors limit feather mite abundance across European passerines. Their quantitative analyses indicate that the number of feather barbs limits mite abundance across host species, suggesting that mite populations are spatially, but not energetically, constrained. These findings not only reveal mechanisms that may drive the variation in feather mite abundances across hosts, but also advance our understanding of the ecology of interspecific interactions more generally.

Alterations induced by Colomerus vitis on the structural and physiological leaf features of two grape cultivars.

Vitis vinifera is cultivated worldwide for its high nutritional and commercial value. More than 60 grape cultivars are cultivated in Chile. Two of these, the país and the corinto cultivars, are the oldest known and widely used for the preparation of traditional homemade drinks and consumption as table grapes. These two grape cultivars are affected by Colomerus vitis, an eriophyid mite which establishes on their leaves and forms erinea, where the mite and its offspring obtain shelter and food. Although C. vitis has a cosmopolitan distribution, few studies of its impact on the structure and physiology of affected plants have been reported. Herein we aimed to evaluate the impact of C. vitis infection on the structural and physiological leaf performance of the two grape cultivars. The results showed tissue hyperplasia and cell hypertrophy in the epidermis, with an overproduction of trichomes and emergences in the abaxial epidermis in both cultivars. The anatomical changes were similar between the país and corinto cultivars, but they were proportionally greater in the país, where the area affected by the erinea were greater. No significant changes were detected in the photosynthetic pigment content; however, there was an increase in the total soluble sugars content in the erineum leaves of the país cultivar. Higher contents of anthocyanins and total phenols, as well as the presence of the pinocembrin in the corinto cultivar, which was less affected by C. vitis, could also indicate some resistance to mites' attack, which should be investigated in future studies.

Adaptation of an arthropod predator to a challenging environment is associated with a loss of a genome-wide plastic transcriptional response.

BACKGROUND: Structural and chemical plant defence traits may reduce the efficacy of biological control agents in integrated pest management. Breeding programmes have shown arthropod predators' potential to acclimate to challenging host plants. However, whether and how these predators adapt to novel plant environments remain unclear. Using the predatory mite Phytoseiulus persimilis - herbivorous mite Tetranychus urticae system in an experimental evolution setup, we studied the adaptation mechanisms to tomato and cucumber, plants that possess a distinct repertoire of defensive traits. RESULTS: Experimental evolution experiments on whole plants revealed that allowing P. persimilis to adapt to tomatoes led to an ~100% larger population size. Independent feeding assays showed that tomato- and cucumber-adapted prey reduced predator fecundity. The deleterious effect of ingesting low-quality prey persisted after adaptation of the predator to both cucumber and tomato. We demonstrated that jasmonic acid (JA)-dependent defences reduce prey quality by evaluating predator performance on prey fed on JA defence-deficient tomato plants. Transcriptomic profiling of the replicated P. persimilis lines showed that long-term propagation on tomato and cucumber plants produces distinctive gene-expression levels. Predator adaptation to tomatoes results in the loss of a large transcriptional response, in which predicted cuticle-building rather than detoxification pathways are affected. CONCLUSION: We showed that the adaptation of predatory arthropods to a novel, challenging plant does not necessarily occur via the prey, but rather through the physical environment of the plant. We provided first insights into the underlying molecular mechanisms. © 2023 Society of Chemical Industry.

Osmotin1 is involved in rice resistance to Schizotetranychus oryzae (Acari: Tetranychidae) infestation.

BACKGROUND: Rice is one of the most consumed cereals in the world. Productivity losses are caused by different biotic stresses. One of the most common is the phytophagous mite Schizotetranychus oryzae Rossi de Simons (Acari: Tetranychidae), which inhibits plant development and seed production. The identification of plant defense proteins is important for a better understanding of the mite-plant interaction. We previously detected a high expression of Osmotin1 protein in mite-resistant rice cultivars, under infested conditions, suggesting it could be involved in plant defense against mite attack. We therefore aimed to evaluate the responses of three rice lines overexpressing Osmotin1 (OSM1-OE) and three lines lacking the Osmotin1 gene (osm1-ko) to mite attack. RESULTS: The numbers of individuals (adults, immature stages, and eggs) were significantly lower in OSM1-OE lines than those in wild-type (WT) plants. On the other hand, the osm1-ko lines showed larger numbers of mites per leaf than WT plants. When plants reached the full maturity stage, two out of the three infested OSM1-OE lines presented lower plant height than WT, while the three osm1-ko lines (infested or not) presented higher plant height than WT. The reduction in seed number caused by mite infestation was lower in OSM1-OE lines (12-19%) than in WT plants (34%), while osm1-ko lines presented higher reduction (24-54%) in seed number than WT plants (13%). CONCLUSION: These data suggest that Osmotin1 is involved in rice resistance to S. oryzae infestation. This is the first work showing increased plant resistance to herbivory overexpressing an Osmotin gene. © 2023 Society of Chemical Industry.

Functional response of Neoseiulus californicus (Acari: Phytoseiidae) to Tetranychus urticae (Acari: Tetranychidae) at different temperatures.

Environmental factors like temperature have a great impact on the predation potential of biological control agents. In the present study, the functional response of the predatory mite Neoseiulus californicus (Acari: Phytoseiidae) to the pest mite Tetranychus urticae (Acari: Tetranychidae) at moderate to high temperatures under laboratory conditions was determined. The study aimed to understand the prey-predator interaction under different temperatures and prey densities. Five constant temperatures (24 °C, 27 °C, 30 °C, 33 °C, and 36 °C), and thirteen prey densities (4, 5, 8, 10, 12, 15, 16, 20, 24, 25, 30, 32, and 40) of each stage (adult, nymph, larvae, and egg stage) were employed in the experiment. Observations were made 24 h after the start of each experiment. Results revealed that the predatory mites showed type II functional response to adult females of T. urticae, whereas type I to other stages (nymphs, larvae, and eggs) of T. urticae. The predation capability of adult predatory mites on T. urticae was significant at 24-36 °C. The instantaneous attack rate (a) of N. californicus increased and the handling time (Th) decreased with an increase in temperature. The maximum attack rate was recorded at 36 °C (1.28) for the egg stage. The longest handling time was (0.78) for the larval stage of T. urticae at 30 °C. Daily consumption increased with increasing prey density. Maximum daily consumption was observed at 33 °C (30.00) at the prey density of 40. Searching efficiency decreased with the increase in prey density but was found to increase with the rise in temperature. N. californicus was found to be voracious on the larval and egg stages. Conclusively, the incorporation of N. californicus at earlier stages (larvae and eggs) of T. urticae would be beneficial under warm conditions because managing a pest at its initial stage will save the crop from major losses. The results presented in this study at various temperatures will be helpful in different areas with different temperature extremes. The results of the functional response can also be applied to mass rearing, quality testing, and integrated pest management programmes.

Feeding-induced plant metabolite responses to a phoretic gall mite, its carrier psyllid and both, after detachment.

Phoresy is one of the most distinctive relationships between mites and insects, and the off-host interaction between phoretic mites and their carriers is the most critical factor sustaining the phoretic association. As phoretic associations commonly occur in temporary habitats, little is known about off-host interactions between phoronts and carriers. However, an off-host interaction has been reported, in which the plant-mediated competition between a phoretic gall mite, Aceria pallida, and its psyllid vector, Bactericera gobica, after detachment decreases leaf abscission caused by B. gobica and then directly facilitates their phoretic association. In this obligate phoresy, A. pallida seasonally attaches to B. gobica for overwinter survival and they share the same host plant, Lycium barbarum, during the growing season. It is unknown how the host plant responds to these two herbivores and what plant metabolites are involved in their interspecific interaction. Here, effects of A. pallida and B. gobica on the host plant's transcriptome and metabolome, and on enzymes involved in plant defence, at various infestation stages were studied by inoculating A. pallida and B. gobica either separately or simultaneously on leaves of L. barbarum. Our results showed that (a) A. pallida significantly promoted primary and secondary metabolite accumulation, (b) B. gobica markedly inhibited primary and secondary metabolite accumulation and had little influence on defence enzyme activity, and (c) under simultaneous A. pallida and B. gobica infestation, an intermediate response was predicted. These findings indicate that A. pallida and B. gobica have different effects on host plants, A. pallida inhibits B. gobica mainly by increasing the secondary metabolism of L. barbarum, whereas B. gobica inhibits A. pallida mainly by decreasing the primary metabolism of L. barbarum. In conjunction with our previous research, we speculate that this trade-off in host plant metabolite response between A. pallida and B. gobica after detachment promotes a stable phoretic association.

Novel Jasmonic Acid-Coumarin Pathway in the Eggplant That Inhibits Vitellogenin Gene Expression To Prevent Mite Reproduction.

Plants activate direct and indirect defense mechanisms in response to perceived herbivore invasion, which results in negative consequences for herbivores. Tetranychus cinnabarinus is a polyphagous generalist herbivore that inflicts substantial agricultural and horticultural damage. Our study revealed that mite feeding significantly increased jasmonic acid (JA) in the eggplant. The damage inflicted by the mites decreased considerably following the artificial application of JA, thereby indicating that JA initiated the defense response of the eggplant against mites. The transcriptomic and metabolomic analyses demonstrated the activation of the JA-coumarin pathway in response to mite feeding. This pathway protects the eggplant by suppressing the reproductive capacity and population size of the mites. The JA and coumarin treatments suppressed the vitellogenin gene (TcVg6) expression level. Additionally, RNA interference with TcVg6 significantly reduced the egg production and hatching rate of mites. In conclusion, the JA-coumarin pathway in the eggplant decreases the egg-hatching rate of mites through suppression of TcVg6.

Numerical responses of the predatory mites, Cheyletus eruditus (Trombidiformes: Cheyletidae) and Cheyletus malaccensis, to Liposcelis decolor (Psocodea: Liposcelididae).

Predatory mites display diverse ecological mechanisms to suppress pest population density below certain thresholds known to cause economic loss. The current study explored the numerical responses of the predatory mites, Cheyletus eruditus (Schrank) (Trombidiformes: Cheyletidae) and Cheyletus malaccensis Oudemans, to Liposcelis decolor (Pearman) (Psocodea: Liposcelididae). The numerical responses of these 2 cheyletid mites to nymphs, adult males, and adult females of L. decolor were determined under laboratory conditions at 24 ± 1 °C, 85 ± 5 RH, and 0:24 (L:D) photoperiod. Oviposition rate, oviposition efficiency, and efficiency of conversion of ingested (ECI) food resources were the key numerical response parameters assessed. The present study revealed a general trend of a strong negative and positive correlation between oviposition rates and increase in prey densities (number of prey per 16.98 cm2) for C. eruditus and C. malaccensis, respectively. The oviposition efficiency was mostly similar for both predatory mites and was inversely related to prey density. Generally, ECI (%) decreased considerably with increasing prey density across different prey types for both predators, however, C. malaccensis was more efficient than C. eruditus in utilizing prey biomass. Given the relatively weak numerical responses, we recommended further assessment of these predatory mites before recommending their use for managing stored-product insect pests in the United States.

Gene expression analysis of Canine Demodicosis; A milieu promoting immune tolerance.

Canine demodicosis is a common skin disease seen in companion animal practice that results from an overpopulation of the commensal Demodex mite species. Common predisposing factors to the development of canine demodicosis include immunosuppressive diseases, such as neoplasia and hypothyroidism, and administration of immunosuppressive therapies, such as corticosteroids. Despite this, the pathogenesis of development of canine demodicosis remains unclear. Previous studies have implicated a role for increased expression of toll like receptor 2 (TLR2), increased production of interleukin (IL)-10) and T cell exhaustion. Here, we investigate gene expression of formalin fixed paraffin embedded skin samples from twelve cases of canine demodicosis in comparison to twelve healthy controls, using a 770 gene panel (NanoString Canine IO Panel). Results show an increase in the T cell population, specifically Th1 and Treg cells in dogs with demodicosis. In addition, while there is an upregulation of immunosuppressive cytokines such as IL-10 and IL-13, there is also an upregulation of immune check point molecules including PD-1/PD-L1 and CTLA-4. These findings suggest that Demodex spp. mites are modulating the host immune system to their advantage through upregulation of several immune tolerance promoting pathways.

Tissue-specific regulation of volatile emissions moves predators from flowers to attacked leaves.

Plant-predator mutualisms have been widely described in nature.1,2 How plants fine-tune their mutualistic interactions with the predators they recruit remains poorly understood. In the wild potato (Solanum kurtzianum), predatory mites, Neoseiulus californicus, are recruited to flowers of undamaged plants but rapidly move downward when the herbivorous mites, Tetranychus urticae, damage leaves. This "up-down" movement within the plant corresponds to the shift of N. californicus from palynivory to carnivory, as they change from feeding on pollen to herbivores when moving between different plant organs. This up-down movement of N. californicus is mediated by the organ-specific emissions of volatile organic compounds (VOCs) in flowers and herbivory-elicited leaves. Experiments with exogenous applications, biosynthetic inhibitors, and transient RNAi revealed that salicylic acid and jasmonic acid signaling in flowers and leaves mediates both the changes in VOC emissions and the up-down movement of N. californicus. This alternating communication between flowers and leaves mediated by organ-specific VOC emissions was also found in a cultivated variety of potato, suggesting the agronomic potential of using flowers as reservoirs of natural enemies in the control of potato pests.

Presence of nontarget prey, Tetranychus truncatus, affected the predation by Neoseiulus bicaudus on Tetranychus turkestani.

Neoseiulus bicaudus (Wainstein) (Acari: Phytoseiidae) is a generalist predatory mite that consumes several pest species, including Tetranychus turkestani (Ugarov et Nikolskii) (Acari: Tetranychidae) in the Xinjiang Uygur Autonomous Region. The release numbers of predatory mites are based on the populations of target pests and their ability to control them. Populations of T. turkestani and T. truncatus Ehara (Acari: Tetranychidae) often coexist and damage many crops. To determine whether the presence of the non-target prey T. truncatus affects the ability of N. bicaudus to control the target prey T. turkestani. The study evaluated the predation rate and functional response of N. bicaudus to 4 stages of T. turkestani in the presence of T. truncatus. The consumption of T. turkestani by N. bicaudus gradually decreased as the proportion of T. truncatus increased. The functional response of N. bicaudus to T. turkestani was not changed when T. truncatus was presented, which was consistent with a type II response. The attack rate of N. bicaudus on the egg, larva, and nymph of T. turkestani was significantly decreased and the handling time of N. bicaudus on T. turkestani was significantly extended when T. truncatus was presented. The preference index showed that the preference of N. bicaudus for eggs and female adults of T. turkestani decreased with increasing density of T. turkestani in the same proportion as T. truncatus. The presence of T. truncatus can negatively affect the predation of T. turkestani by N. bicaudus. We suggest that the number of N. bicaudus released to control T. turkestani should be increased when T. truncatus coexist.

Expression and functional analysis of transformer-2 in Phytoseiulus persimilis and other genes potentially participating in reproductive regulation.

Transformer-2 (tra-2) is an important sex-determining gene in insects. It also plays a role in the reproduction of phytoseiid mites. We performed bioinformatic analyses for the tra-2 ortholog in Phytoseiulus persimilis (termed Pptra-2), measured its expression at different stages and quantitatively identified its function in reproduction. This gene encodes 288 amino acids with a conserved RRM domain. The peak of its expression was observed in adult females, especially ca. 5 days after mating. In addition, expression is also higher in eggs than in other stages and adult males. When Pptra-2 was silenced through RNA interference with oral delivery of dsRNA, 56% of the females had their egg hatching rates decreased in the first 5 days, from ca. 100% to ca. 20%, and maintained at low levels during the rest of the oviposition period. To detect other genes functionally related to Pptra-2, transcriptome analyses were performed on day 5 after mating. We compared mRNA expressions among interfered females with significantly reduced egg hatching rate, interfered females without significant hatching rate and CK. In total 403 differential genes were identified, of which 42 functional genes involved in the regulation of female reproduction and embryonic development were screened and discussed.

Investigation of peripheral blood responses in chickens infested with Dermanyssus gallinae.

Among haematophagous ectoparasites that infest chickens, poultry red mite (Dermanyssus gallinae, PRM) is one of the most serious threats to poultry farms. Mass PRM infestation causes various health problems in chickens, resulting in significant productivity reduction in the poultry industry. Despite the efficiency of acaricides for controlling PRMs, the emergence of acaricide-resistant PRMs represents a challenging setback. Infestation with haematophagous ectoparasites, such as PRMs, induces inflammatory and haemostatic reactions in the host. Therefore, we aimed to explore the gene expression in chicken peripheral blood cells to elucidate host responses against PRM infestation in detail. RNA sequencing of blood-fed PRMs was performed, and the levels of the chicken-derived transcripts obtained from the ingested blood cells were analysed. Genes encoding haemoglobin subunits were found to be significantly more expressed, suggesting that PRM infestation causes anaemia in chickens. Additionally, the mRNA and plasma concentrations of CC chemokine ligand 4 and ß2 microglobulin among the immune-related molecules were found to be significantly higher in PRM-infested chickens compared with non-infested animals. These results suggest that PRM infestation induce inflammation in chicken. Further studies are warranted to better understand the influence of PRM infestation on the host physiological states, including immunity.

Pathogenesis and defense mechanism while Beauveria bassiana JEF-410 infects poultry red mite, Dermanyssus gallinae.

The poultry red mite, Dermanyssus gallinae (Mesostigmata: Dermanyssidae), is a major pest that causes great damage to chicken egg production. In one of our previous studies, the management of red mites using entomopathogenic fungi was evaluated, and the acaricidal fungus Beauveria bassiana JEF-410 was selected for further research. In this study, we tried to elucidate the pathogenesis of B. bassiana JEF-410 and the defense mechanisms of red mites at a transcriptome level. Red mites collected from a chicken farm were treated with B. bassiana JEF-410. When the mortality of infected red mites reached 50%, transcriptome analyses were performed to determine the interaction between B. bassiana JEF-410 and red mites. Uninfected red mites and non-infecting fungus served as controls. In B. bassiana JEF-410, up-regulated gene expression was observed in tryptophan metabolism and secondary metabolite biosynthesis pathways. Genes related to acetyl-CoA synthesis were up-regulated in tryptophan metabolism, suggesting that energy metabolism and stress management were strongly activated. Secondary metabolites associated with fungal up-regulated DEGs were related to the production of substances toxic to insects such as beauvericin and beauveriolide, efflux pump of metabolites, energy production, and resistance to stress. In red mites, physical and immune responses that strengthen the cuticle against fungal infection were highly up-regulated. From these gene expression analyses, we identified essential factors for fungal infection and subsequent defenses of red mites. These results will serve as a strong platform for explaining the interaction between B. bassiana JEF-410 and red mites in the stage of active infection.

Suppressive modulation of host immune responses by Dermanyssus gallinae infestation.

The poultry red mite (Dermanyssus gallinae, PRM) is a blood-sucking ectoparasite in chickens and is one of the most serious threats to poultry farms. Mass infestation with PRMs causes various health problems in chickens, resulting in significant productivity reduction in the poultry industry. Infestation with hematophagous ectoparasites, such as ticks, induces host inflammatory and hemostatic reactions. On the other hand, several studies have reported that hematophagous ectoparasites secrete various immunosuppressants from their saliva to suppress host immune responses to maintain blood sucking. Here, we examined the expression of cytokines in peripheral blood cells to investigate whether PRM infestation affects immunological states in chickens. In PRM-infested chickens, anti-inflammatory cytokines, IL-10 and TGF-ß1, and immune checkpoint molecules, CTLA-4 and PD-1, were highly expressed compared to noninfested chickens. PRM-derived soluble mite extracts (SME) upregulated the gene expression of IL-10 in peripheral blood cells and HD-11 chicken macrophages. In addition, SME suppressed the expression of interferons and inflammatory cytokines in HD-11 chicken macrophages. Moreover, SME induces the polarization of macrophages into anti-inflammatory phenotypes. Collectively, PRM infestation could affect host immune responses, especially suppress the inflammatory responses. Further studies are warranted to fully understand the influence of PRM infestation on host immunity.

Predation stress experienced as immature mites extends their lifespan.

The early-life experience is important in modulating the late-life performance of individuals. It has been predicted that there were trade-offs between early-life fitness and late-life success. Most of the studies on senescence have focused on the trade-offs between the reproduction and lifespan, and the influences of diet, mating, and other factors. Because the negative, non-consumptive effects of predators could also modulate the behaviour and underlying mechanisms of the prey, this study aimed to examine the different effects of predator-induced stress experienced in the early life compared with later life of the prey. The prey (Tyrophagus putrescentiae) was exposed to predation stress from the predator (Neoseiulus cucumeris) during different periods of its life (immature, oviposition period, and post-oviposition period). The results showed that the predation stress experienced during immature stages delayed development by 7.3% and prolonged lifespan by 9.7%, while predation stress experienced in the adult stage (both oviposition and post-oviposition periods) decreased lifespans of T. putrescentiae (by 24.8% and 28.7%, respectively). Predation stress experienced during immature stages also reduced female fecundity by 7.3%, whereas that experienced during the oviposition period reduced fecundity of the prey by 50.7%. This study demonstrated for the first time lifespan extension by exposure to predation stress when young and highlighted the importance of early-life experience to aging and lifespan.

More than just a substrate for mites: Moss-dominated biological soil crust protected population of the oribatid mite, Oppia nitens against cadmium toxicity in soil.

Metal-impacted sites often need aggressive ecorestoration strategies to restore a functional plant-soil system. The use of biological soil crusts for soil stabilization, moisture retention and C and N input in disturbed and contaminated soils is becoming a more common ecorestoration practice. Biological soil crusts comprise cyanobacteria, fungi, lichens, and bryophytes (mostly moss). Moss-dominated BSCs provide significant N mineralization rate in most terrestrial ecosystems. Oribatid mites or moss mites dominate moss-dominated BSCs and provide essential ecosystem services such as decomposition and nutrient cycling. We hypothesized that moss-dominated BSCs would create a high-quality habitat niche for O. nitens to resist Cd-induced toxicity. Adult mites were exposed to Cd for 28 days in soil with or without BSCs that were aged for eight months. Cadmium toxicity to mites in soil without BSCs was 1.7 and 5.4times greater than in soil with BSCs, respectively for the mites reproduction and instantaneous population growth rate (PGRi). The moss-dominated BSC did not reduce Cd bioavailability in the mites but increased the mite's resilience to Cd toxicity, likely mediated by the trophic transfer of calcium from the BSC to the mites. Our work identifies a second mechanistic avenue by which BSCs are useful for ecorestoration, i.e., the improvement of soil invertebrate physiology to resist metal stress.

Attractant Activity of Host-Related Chemical Blends on the Poultry Red Mite at Different Spatial Scales.

Many blood-feeding arthropods use volatile organic compounds (VOCs) to detect their vertebrate hosts. The role of chemical interactions in mediating the behavior of hematophagous insects and ticks has been investigated before but remains poorly understood in hematophagous mesostigmatic mites. The poultry red mite Dermanyssus gallinae is an obligatory blood-sucking mesostigmatic mite that feeds on birds and causes damage in poultry farms. We characterized the attractive response of D. gallinae to candidate VOCs previously reported from the odor emitted by living hens. We performed in-vitro choice-test bioassays as well as semi-field and field trials using baited and unbaited traps, in the presence and absence of hens. Among different tested combinations of VOCs, a blend of 5 VOCs (mix1.0) was significantly attractive to our reference population of D. gallinae in vitro, whereas the same individual compounds tested alone were not attractive. Ammonia was attractive on its own and increased the mix1.0 attractiveness. The attractiveness of mix1.0 was confirmed at 'natural' spatial scales in the absence of hens both at the lab and on the farm that provided the reference population. The presence of hens inhibited the mix1.0 attractiveness. The attractive power of mix1.0 was not found in other farms. This research is an important step to advance our understanding of host-parasite interactions in hematophagous mesostigmatic mites and paves the way for developing alternative control tools against D. gallinae by interfering with chemical interactions. Moreover, it underlines the importance of assessing kairomonal activity on different pest populations when developing attract-and-kill systems.