Predatory Mite Species Research Articles

Spirodiclofen toxicity in Tetranychus urticae and safety to natural enemies Proprioseiopsis asetus and Amblyseius swirskii

Proprioseiopsis asetus and Amblyseius swirskii are excellent natural enemies of plant-feeding mites and small pests. In order to clarify the safety of the acaricide spirodiclofen to the predatory mites P. asetus and A. swirskii, here, we investigated the toxicity of the acaricide on the pest mite T. urticae (nymphs and adult females) and on both species of predatory mites, P. asetus and A. swiskii (eggs, nymphs, and female adults) by using the spray, slide-dip, and leaf residual toxicity methods, compared the selective toxicity and assessed the safety to these natural enemies. The results demonstrated that the corrected mortality in P. asetus and A. swirskii female adults was <5% at recommended spirodiclofen concentrations in the spray method. In the leaf residual toxicity method, P. asetus and A. swirskii egg-hatching rates did not differ significantly from the pure water control group. In the slide-dip method, spirodiclofen lethal concentration 50 (LC50) in P. asetus and A. swirskii female adults was noted to be 9,494.875 and 3,064.187 mg·L−1, respectively. In the spray method, spirodiclofen LC50 in P. asetus and A. swirskii nymphs was found to be 4,292.664 and 1,081.609 mg·L−1, respectively, and that in T. urticae female adults and nymphs was 55.189 and 40.862 mg·L−1, respectively. Spiroclofen selective toxicity ratios (STRs) in P. asetus female adults–T. urticae and P. asetus nymphs–T. urticae were 172.013 and 105.053, respectively, indicating that spiroclofen has a high positive selectivity toward the pest T. urticae and its natural enemy P. asetus. In contrast, spiroclofen STRs in A. swirskiis female adults–T. urticae and A. swirskiis nymphs–T. urticae were 55.522 and 26.470, respectively, indicating spiroclofen has a moderate positive selectivity toward the pest T. urticae and its natural enemy A. swirskii. In the safety evaluation, the spirodiclofen safety factor for P. asetus female adults and nymphs was 158.248–237.37 and 71.544–107.317, respectively, whereas that for A. swirskii female adults and nymphs was 50.070–76.605 and 18.027–27.040 respectively. All spirodiclofen safety factor values were much higher than 5, indicating that spirodiclofen is highly safe for P. asetus and A. swirskii; in particular, spirodiclofen is safer for P. asetus than for A. swirskii.

Host egg volatiles are involved in brood parasitism in predatory mites

Abstract Recently, we reported brood parasitism in the tiny predatory mite Neoseiulus californicus (Acari: Phytoseiidae); adult females of this species prefer to add their eggs to a cluster of eggs of another predatory mite species, Gynaeseius liturivorus (Acari: Phytoseiidae), which guards its own eggs against egg predators. Here, we investigated the cues used by the blind N. californicus to detect eggs of G. liturivorus. We show that N. californicus locates oviposition sites of G. liturivorus using volatiles emanating from eggs of the latter species. Adult female G. liturivorus spent more time guarding oviposition sites that contain more eggs, which resulted in a higher per capita survival of the eggs. We therefore hypothesized that N. californicus would prefer oviposition sites with more G. liturivorus eggs. Indeed, N. californicus preferably laid their egg at oviposition sites containing more than six G. liturivorus eggs, which corresponds to the average number laid by a female G. liturivorus during 1 day. Our results suggest that N. californicus uses egg volatiles to localize oviposition sites of G. liturivorus, where the eggs of the former are effectively protected against egg predators.

Functional responses of two species of predatory mites (Acari: Phytoseiidae) to eggs and first-instar nymphs of Bactericera Gobica Logniova (Homoptera: Psyllidae).

The goji berry psyllid, Bactericera gobica Logniova (Homoptera: Psyllidae), is one of the most important pests on goji berry plants (Lycium barbarum L.), whose fruits are widely used in traditional Chinese medicine and food. However, chemical control is still the predominant control strategy of this pest. Recently, two species of predatory mites, Neoseiulus setarius Ma, Meng & Fan and Neoseiulus barkeri Hughes were found to be associated with B. gobica in China. To assess their predation potential against B. gobica, the functional responses of these two phytoseiid species feeding on different densities (2, 4, 8, 12, 16, 24 and 32 individuals) of B. gobica eggs and 1st instar nymphs were compared at a temperature of 25ºC ± 1º C. Logistic regression analysis revealed that both predatory mite species exhibited type Holling-II functional responses on eggs and 1st instar nymphs of B. gobica, with the predation number increased for both predators as the density of prey increased. Overall, N. setarius consumed more prey compared to N. barkeri across all levels of prey densities. Meanwhile, the highest attack rate (α = 0.0283), the lowest handling time (Th = 1.1324h prey- 1), and the highest estimated maximum predation rate (T/Th = 21.19 prey day- 1) were all observed for N. setarius fed with 1st instar nymphs of B. gobica. These findings suggest that it is worthy considering utilizing N. setarius and N. barkeri as candidate biocontrol agents of B. gobica, with N. setarius appearing to be a more effective predator than N. barkeri.

Neoseiulus mites as biological control agents against Megalurothrips usitatus (Thysanoptera: Thripidae) and Frankliniella intonsa (Thysanoptera: Thripidae) on cowpea crop: laboratory to field.

Megalurothrips usitatus (Bagnall) (Thysanoptera: Thripidae) and Frankliniella intonsa (Trybom) (Thysanoptera: Thripidae) have been detrimental to cowpea production in many countries. Laboratory experiments were conducted to determine the prey stage preference and functional response of 2 predatory mites species, Neoseiulus barkeri (Hughes) (Acari: Phytoseiidae), and Neoseiulus californicus (McGregor) (Acari: Phytoseiidae), towards 2 thrips species (TS), M. usitatus, and F. intonsa, at varying densities and life stages on cowpea. Results shown that Neoseiulus species had a preference for different life stages of prey. Neoseiulus barkeri consumed more M. usitatus nymphs, while N. californicus consumed more F. intonsa (second-instar nymphs). The functional response of the 2 Neoseiulus spp. to nymphs of 2 TS was Type II on cowpea. The higher attack rate coefficient (a') and shorter handling time (Th) values were found on N. barkeri against M. usitatus, and a similar trend was found for those in N. californicus against F. intonsa. Field-caged trials were conducted to evaluate the effectiveness of Neoseiulus spp. in controlling 2 TS. The results have shown that Neoseiulus spp. was effective in controlling the 2 TS, with varying control efficacies at high or low release rates. The study provided valuable information on using Neoseiulus spp. as biological control agents against M. usitatus and F. intonsa in cowpea crops.

Morphological variation and abnormalities in two species of Typhlodromus Scheuten (Acari: Phytoseiidae)</p >

Typhlodromus (Anthoseius) bagdasarjani Wainstein & Arutunjan and T. (A.) khosrovensis Arutunjan have been frequently recorded from Iran. While investigating the population dynamics of these two predatory mite species on white mulberry in 2022 and 2023, in Tehran (Iran), our study unveiled intriguing morphological abnormalities and variations. Specifically, variations were observed in the number of dorsal shield solenostomes, insertion of ventrianal setae, shape of spermatheca and length of peritreme. In this context, detailed re-descriptions for both species are presented, accompanied by documentation of the observed abnormalities and variations.

Acute toxicity effects of pesticides on predatory snout mites (Trombidiformes: Bdellidae).

Predatory mites biologically control a range of arthropod crop pests and are often central to agricultural IPM strategies globally. Conflict between chemical and biological pest control has prompted increasing interest in selective pesticides with fewer off-target impacts on beneficial invertebrates, including predatory mites. However, the range of predatory mite species included in standardized pesticide toxicity assessments does not match the diversity of naturally occurring species contributing to biocontrol, with most testing carried out on species from the family Phytoseiidae (Mesostigmata). Here, we aim to bridge this knowledge gap by investigating the impacts of 22 agricultural pesticides on the predatory snout mite, Odontoscirus lapidaria (Kramer) (Trombidiformes: Bdellidae). Using internationally standardized testing methodologies, we identified several active ingredients with minimal impact on O. lapidaria mortality, including Bacillus thuringiensis,nuclear polyhedrosis virus, flonicamid, afidopyropen, chlorantraniliprole, and cyantraniliprole, which may therefore be good candidates for IPM strategies utilizing both chemical and biological control. Comparison of our findings with previous studies on Phytoseiid mites reveals important differences in responses to a number of chemicals between predatory mite families, including the miticides diafenthiuron and abamectin, highlighting the risk of making family-level generalizations from acute toxicity assessments. We also tested the impacts of several pesticides on a second Bdellidae species (Trombidiformes: Bdellidae)and found differences in the response to chlorpyrifos compared with O. lapidaria, further highlighting the taxon-specific nature of nontarget toxicity effects.

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

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

Are predatory mites effective as biological control agents to suppress Oligonychus ilicis (Acari: Tetranychidae) in blueberry plantings?

Southern red mite, Oligonychus ilicis McGregor (Acari: Tetranychidae), is an important polyphagous spider mite pest that causes economic damage to many ornamentals, coffee, and fruit crops. Blueberry growers in the Southeastern United States, including Florida and Georgia, have experienced severe losses due to outbreaks of O. ilicis. Predatory mites are an important management tool used for controlling spider mites; however, predators have not been studied and successfully evaluated in blueberry systems. Amblyseius swirskii Athias-Henriot, Phytoseiulus persimilis Athias-Henriot, and Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) are among the most economically important arthropod agents used in augmentative biological control worldwide. To evaluate the potential of these 3 commercially available predatory mites for use in blueberry plantings, we conducted experiments under controlled laboratory conditions and in the greenhouse. In preliminary laboratory experiments, P. persimilis and N. californicus significantly reduced the number of O. ilicis motile stages below those found in the untreated control, indicating the potential for these 2 predatory mite species to suppress O. ilicis populations. Amblyseius swirskii did not perform well controlling O. ilicis motiles in the laboratory. Under greenhouse conditions, N. californicus and P. persimilis significantly reduced the number of eggs after 7 days of release and the number of motile stages after 14 days of release. This is the first report of using phytoseiid mites to suppress O. ilicis in blueberry systems in the United States. Further studies on predator behavior, feeding preferences, and acaricide compatibility with predators are required to investigate the possibility of using P. persimilis, and N. californicus as biological control agents of O. ilicis in blueberry systems.

Effects of Various Nectar and Pollen Plants on the Survival, Reproduction, and Predation of Neoseiulus bicaudus.

Neoseiulus bicaudus is a predatory mite species that could potentially be used for the biological control of spider mites and thrips. Floral resources can provide excellent habitats and abundant nutrients for natural enemies. The objective of this experiment was to evaluate the effects of eight floral resources on the longevity, fecundity, and predation ability of N. bicaudus. Among the considered plants, Cnidium monnieri led to the highest longevity (24 days) and fecundity (13.8 eggs) of N. bicaudus, while Tagetes erecta resulted in the lowest longevity (7 days) and fecundity (0.1 eggs) observed in the predatory mites. By comparing the effects of three nectar and pollen plants on the predation of predatory mites, it was observed that N. bicaudus still exhibited a type II functional response to Tetranychus turkestani. In the presence of pollen, the predation efficacy (a/Th) of N. bicaudus exhibited a lower value, compared to that in the absence of pollen (Control: a/Th = 24.00). When pollen was supplied, the maximum consumption (1/Th) of predatory mites was higher than in its absence (Control: 1/Th = 9.90 d-1), with the highest value obtained in the presence of B. officinalis pollen (B. officinalis: 1/Th = 17.86 d-1). The influence coefficient of predation of N. bicaudus on T. turkestani in the presence of pollen was compared in the presence of three nectar and pollen plants: Cnidium monnieri, Centaurea cyanus, and Borago officinalis. At low prey densities, the influence coefficient of C. cyanus exceeded that of B. officinalis, and the overall influence coefficient values were negative (i.e., the presence of pollen reduced predatory mite feeding on T. turkestani). They exhibited similar values at high prey densities, and all of the influence coefficient values were close to 0 (i.e., the presence of pollen had no effect on predatory mite feeding on T. turkestani). The findings revealed that diverse plant species exert differential impacts on N. bicaudus, with some influencing its lifespan and others affecting its reproductive capabilities. Furthermore, the presence of nectar and pollen plants had a significant impact on predatory mite feeding on T. turkestani at low prey densities; however, this effect diminished as the prey density increased. Therefore, we recommend planting C. monnieri, C. cyanus, and B. officinalis in the field to ensure an ample population of predatory mites. The obtained results hold significant implications for the utilization of nectar and pollen plants in eco-friendly pest management strategies within agricultural contexts.

Sister predatory mites collectively protect their eggs against predators.

Group-living animals sometimes cooperatively protect their offspring against predators. This behavior is observed in a wide range of taxa but, to the best of our knowledge, this is the first report of its occurrence in arthropods that are not eusocial. Adult female predatory mites Gynaeseius liturivorus protect their eggs against egg predators, the predatory mite species Neoseiulus californicus. In the field, several adult female G. liturivorus were often found on the same plant structures such as folded leaves. We tested whether these females might protect their eggs cooperatively, focusing on kinship between the females. When two adult female G. liturivorus were kept in the absence of egg predators, their reproduction was not affected by their kinship. The presence of egg predators reduced the number of G. liturivorus eggs. However, reproduction of two G. liturivorus sisters was higher than that of two non-sisters. Together, sisters guarded the oviposition site longer than non-sisters. We further tested if non-sisters increased egg guarding by having developed together from eggs to adults and found no such effect. Although it remains unclear how adult female G. liturivorus recognize conspecifics as kin or sisters, our results suggest that G. liturivorus sisters reduced predation on their offspring by cooperatively guarding their eggs.

Measurement of Fitness and Predatory Ability of Four Predatory Mite Species in Tibetan Plateau under Laboratory Conditions.

Predatory mites are biological control agents used in many countries against various vegetable pests, particularly spider mites. Despite the significant presence of predatory mites in the Tibetan plateau, there is limited research on their potential against spider mites in the area. This study investigated the fitness parameters and performance against TSSM of four predatory, including Amblyseius swirskii (Athias-Henriot) and three species from the genus Neoseiulus (Neoseiulus californicus (McGregor), Neoseiulus barkeri (Hughes), and Neoseiulus cucumeris (Oudemans)), originally collected from fields in the Tibetan Plateau. Compared to the other three predatory species, A. swirskii exhibited the highest fecundity (11.60 ± 0.34) and the highest pre-adult survival rate (83.33 ± 3.33%). Since their juvenile survival rate (SR) was extremely low (13.33% ± 5.77%), most N. barkeri nymphs died before emergence. Compared to the other three predatory mites, A. swirskii showed the highest predation capacity against adult TSSMs at 15 d post-release (14.28 ± 2.24). Based on the results, A. swirskii was the most effective, and N. barkeri was the least effective in controlling two-spotted mites in the Tibetan Plateau among the four species tested in this study. Collectively, these findings imply notable advantages in employing A. swirskii for controlling two-spotted mites in the Tibetan Plateau. This study informs the development of a feasible biological control method based on suitable predatory mite species to manage TSSMs in the Tibetan Plateau.

Predator-prey interactions: How thrips avoid predation

Biological pest control is successful in many agricultural systems, yet various pests can still not be controlled with natural enemies. Examples are invasive thrips species such as Echinothrips americanus Morgan and Thrips parvispinus (Karny) in Europe. The lack of biological control of these pests in several crops has been subscribed to their complex life cycle and cryptic behaviours, but their antipredator behaviours may prevent successful control and have not been studied extensively. One of these behaviours is the potential of thrips to kill the eggs of predatory mites, which we quantified. Furthermore, we observed the behaviour of first- and second-instar thrips larvae when attacked by starved predatory mites Amblyseius swirskii Athias-Henriot. For comparison, we included Frankliniella occidentalis (Pergande), which shows an array of defensive behaviours, but can be controlled successfully by several species of predatory mites. Second-instar larvae and adults of F. occidentalis and T. parvispinus killed predator eggs, but E. americanus did not. First- and second-instar larvae of all three species swung their abdomen to defend themselves, and F. occidentalis and T. parvispinus produced anal droplets, which are also involved in defence. Predators were not successful in attacking any second-instar larvae during 15-minute observations, which is sufficiently long for an attack. First-instar larvae of F. occidentalis and T. parvispinus were sometimes successfully attacked by the predatory mite before they could mount a defence, but first-instar E. americanus always defended themselves and were almost never preyed upon. Cooling thrips larvae to suppress antipredator behaviour increased predation for all species and stages, except for first instars of F. occidentalis. In conclusion, the lack of successful control of E. americanus is not caused by killing predator eggs, but by the efficient defensive behaviour of both larval instars. Our study furthermore suggests that T. parvispinus can potentially be controlled by A. swirskii.

Three new species of Amblyseius Berlese (Mesostigmata: Phytoseiidae) from Altai Republic, Russia

Three new species of predatory mites belonging to the genus Amblyseius Berlese (Acari: Phytoseiidae), A. latisetosus sp. nov., A. unodentatus sp. nov., and A. altaiensis sp. nov. are described based on the material collected from Altai Republic, Russia. The new species are assigned to the obtusus species group and andersoni species subgroup by having setae J2 and Z1, short and minute setae z4, sub-pentagonal ventrianal shield, and bell-shaped calyx of spermatheca. All new species were compared with each other and all other Amblyseius species known to date. The main diagnostic characters of these species are measurements of prominent dorsal setae, ventral setae JV5 and macrosetae on leg IV, cheliceral dentition, number of setae on genu II as well as small rounded and distinct pre-anal pores on ventrianal shield.

Comparison of chemosensilla in three phytoseiid mites with different feeding habits

Phytoseiidae comprised over 2000 described species with different feeding habits. However, the mechanisms of food selection were virtually unknown in most phytoseiid mites. To explore the potential mechanism of odor perception, we compared the type and number of chemosensilla on the tarsi of legs and pedipalps by scanning and transmission electron microscopy in three representative predatory mites, i.e., Phytoseiulus persimilis (specialized predator of Tetranychus), Neoseiulus californicus (selective predator of tetranychid mites), and Amblyseius swirskii (generalist predator). All three species had two types of putatively olfactory sensilla, with a porous vs. grooved surface on the tip of the first pair of legs. Of these, five porous setae were found in each of the three species of predatory mites studied. However, only one grooved seta was found at the tip of the first pair of legs in P. persimilis, and two in A. swirskii and N. californicus. In addition, the pedipalp has nine grooved setae, which were hypothesized to be contact chemosensilla in each of the three species. No porous setae were found on either pedipalp or the other three pairs of legs, i.e., leg II, III and IV. Additionally, we provided a new chaetotactic notation for the tarsus of leg I by considering the type and number of setae based on our observation of the three species of Phytoseiidae studied.

A new species and a new record of Leioseius Berlese (Acari: Mesostigmata: Ascidae) from Russia, with a review of the Russian species of the genus

A new predatory mite species of the genus Leioseius Berlese, L. subarcticus Joharchi n. sp., is described and illustrated on the basis of morphological characters of adults collected in the subarctic zone of northern Tyumen, from the soil covered with lichens. We also provide additional morphological information and new illustrations for L. changbaiensis Yin and Bei. The species known only from the type series, was found under bark in China (Changbai Mountains, Jilin Province) and is now recorded for the first time in the Altai Republic, Russia, close to type locality from the same habitat. In addition, an identification key to all known Russian species of the genus is presented.

Pollen as sole food source for two generalist predatory mite species (Acari: Phytoseiidae)

Amblyseius largoensis and Typhlodromus ornatus (Acari: Phytoseiidae) are generalist predatory mites that naturally inhabit coconut plantations and other tropical crops. We assessed the suitability of two coconut pest mites, Raoiella indica (Acari: Tenuipalpidae) and Aceria guerreronis (Acari: Eriophyidae); the storage mite Tyrophagus putrescentiae (Acari: Acaridae); honey; and the pollens of castor bean, Ricinus communis, and cattail, Typha domingensis, and their mixture, as food sources for the mass rearing of A. largoensis and T. ornatus. Both pollens, supplied singly or mixed, generated the highest progeny production by both A. largoensis and T. ornatus, and were therefore selected for further life table studies. The pollen diets did not influence the survival of A. largoensis whereas there was higher survivorship of T. ornatus fed on the mixed pollen diet than on R. communis pollen alone. The maximum oviposition rate of both A. largoensis and T. ornatus occurred at the beginning of adulthood, irrespective of the pollen diet. Overall, the life table parameters indicated that the pollen of R. communis for A. largoensis, and R. communis with the mixed pollen diet for T. ornatus, were the best regarding population growth and reproduction. Collectively, our results indicate that A. largoensis and T. ornatus can survive and reproduce excellently when fed solely on R. communis or on the mixed pollen diet. In addition, these results point to the potential of pollen supplementation for the enhancement of the efficiency of these predators in conservation biological control.

The indigenous species of predatory mites (Acari: Phytoseiidae) as biological control agents of plant pests in Slovenia

Phytoseiid mites are of great importance for the biological control of spider mites, thrips, and whiteflies. In this article, we present six species of predatory mites from the family Phytoseiidae, which are included in the list of indigenous organisms for biological control in Slovenia. These species are Amblyseius andersoni, Neoseiulus californicus, N. barkeri, N. cucumeris, Euseius gallicus, and Typhlodromus pyri. Being included in the list mentioned above, these species have great potential to be used in biological control and are technically qualified sources for the management of several pest species in agricultural production in Slovenia. Detailed information about the feeding habits, food preferences, and biological control potentials of these species is presented herein.

Bacterial microbiota of three commercially mass-reared predatory mite species (Mesostigmata: Phytoseiidae): pathogenic and beneficial interactions

Phytoseiidae predatory mites are used as biological control agents in glasshouse environments to control pestiferous mites and insects. The influence of the microbiomes on these mites within mass-reared facilities is largely unknown; this study aims to improve our understanding of the Phytoseiidae microbiome. We used Sanger sequencing and traditional culturing methods to characterise the dominant species within the external and internal bacterial microbiotas of three commercially reared predatory mites: Phytoseiulus persimilis, Typhlodromips (=Amblyseius) swirskii, and Neoseiulus (=Amblyseius) cucumeris. The effects of selected bacterial taxa on the survival, voracity, and oviposition of P. persimilis under lab conditions were also examined. A total of 34 different OTUs were found from three phyla (Actinobacteria, Proteobacteria, and Firmicutes), 12 families, and 22 genera. N. cucumeris had 17 OTUs, compared to 15 from P. persimilis and 12 from T. swirskii. Significant differences were found between internal and external microbiota for each mite species, suggesting functional differences. Principal component analysis (PCA) of bacterial diversity between mite species showed that T. swirskii and N. cucumeris microbiotas were more similar, compared to P. persimilis. This could be due to the characteristics of the environment in which N. cucumeris and T. swirskii are reared, and the use of factitious Astigmata prey. Phytoseiidae microbiotas were found to contain bacterial taxa previously isolated from Astigmata mites. Also, Acaricomes phytoseiuli was isolated from the integument of P. persimilis and T. swirskii; this bacterium has previously been suggested as a pathogen of P. persimilis. Bacteria from gut extracts and body surfaces were cultured and selected taxa were inoculated onto P. persimilis within controlled leaf disc experiments. Of the seven bacterial species tested, Serratia marcescens significantly reduced mite survival, voracity, and oviposition; however, a closely related species, Serratia odorifera, significantly increased mite voracity. Mites showed the highest survival rates and highest mean ages at death in the presence of Elizabethkingia sp. and Staphylococcus kloosii, but these results were not significantly different to the control. The implications of these findings are discussed in the context of benefits to mass rearing and the health of predatory mites in these systems.

Preliminary Studies on the Predation of the Mite Blattisocius mali (Acari: Blattisociidae) on Various Life Stages of Spider Mite, Thrips and Fruit Fly.

Research in recent years has shown that some species of predatory mites, considered to be typically associated with soil and litter, can also be found on plants. Such species include Blattisocius mali, which is an effective predator of acarid mites, nematodes and the eggs of moths and which can disperse by means of drosophilid fruit flies. Apart from soil and litter or storage, it has also been recorded on the bark of apple trees and the leaves of strawberries, thus suggesting its possible predation of/feeding on herbivorous mites and insects. Our goal was to examine whether B. mali could consume different development stages of two polyphagous herbivores, the two-spotted spider mite, Tetranychus urticae, and the western flower thrips, Frankliniella occidentalis, as well as the drosophilid fruit fly Drosophila hydei. In 24 h cage tests, single, starved B. mali females consumed all types of prey offered, i.e., the eggs, males and females of spider mites; the first-instar larvae and prepupae of thrips; and the eggs and first-instar larvae of fruit flies. The potential for B. mali to prey upon these insects and mites was confirmed. However, to estimate whether it can also effectively reduce their population, additional tests on the predator's survival, fecundity and prey preference are needed.

Larval feeding types shape the predation aggression of predatory mites in both intraspecific and interspecific encounters

Cannibalism (intraspecific predation) and intraguild (interspecific) predation are widely observed phenomena in the animal kingdom, including amongst predatory mites of the Phytoseiidae family. While the larval stage of phytoseiids is a vulnerable and important life stage, it has received less attention than the adult stage. The larvae of phytoseiid species can be categorised into three types based on their feeding behaviour: non-feeding, facultative feeding, and obligatory feeding. This study aimed to investigate the occurrence of cannibalism and intraguild predation among the larval stages of three generalist predatory phytoseiids: Amblydromalus limonicus (Garman & McGregor), Amblyseius herbicolus (Chant), and Neoseiulus cucumeris (Oudemans). We hypothesised that the larval feeding type could influence the aggressiveness of the predators in intraspecific and interspecific encounters, with obligatory-feeding larvae being the most aggressive and non-feeding larvae being the least aggressive. To test this hypothesis, we conducted a no-choice experiment under laboratory conditions using larvae to observe the prevalence of predation among conspecifics and heterospecifics in these three predatory mite species. In addition to observing predation outcomes, we measured larval body size, cheliceral size, and cheliceral morphology to investigate these parameters’ correlation with predation success. Our study revealed significant differences in the prevalence of cannibalism and intraguild predation among the three predatory species in agreement with our hypothesis: N. cucumeris larvae did not engage in predatory behaviours, while A. herbicolus displayed the highest predation success. Our findings suggest that cheliceral morphology may be a better indicator than body size of the aggressiveness of larval predation against conspecifics and heterospecifics. Our results provide valuable insights into the importance of larval behaviour in population dynamics and the development of effective pest management strategies. The study also highlights the need for further research on the larval stage of phytoseiids and emphasises the significance of considering larval behaviour when studying and managing these important predatory mites.