Predatory Mite Research Articles

Foraging behaviors of Amblyseius swirskii Athias-Henriot and Euseius scutalis (Athias-Henriot) (Acari: Phytoseiidae) feed on the invasive pest, Eutetranychus orientalis (Klein) (Acari: Tetranychidae)

BackgroundRecent population outbreaks of citrus brown mite, Eutetranychus orientalis (Klein) (Acari: Tetranychidae), were observed in the Çukurova region, a region that supplies approximately 80% of total citrus production in Turkey. Therefore, to obtain preliminary data, regarding biological control of this pest, functional and numerical responses of two commonly found predatory mites, Amblyseius swirskii Athias-Henriot and Euseius scutalis (Athias-Henriot) (Phytoseiidae) in citrus orchards, to egg and protonymph stages of E. orientalis were determined under laboratory conditions.ResultsIn the experiments, six different prey densities (1, 5, 10, 20, 40 and 80) for each selected biological stage of the prey were provided to the predatory mite for 24 h. According to results, the proportion of prey consumed by A. swirskii decreased with increasing egg and protonymph stages of the prey densities. Similarly, the proportion of protonymph consumption of E. scutalis decreased with increasing prey densities, but egg consumption of the predator showed no discernible response to increasing densities. A. swirskii exhibited a type II functional response in both prey stages, whereas E. scutalis showed a type II response only for the protonymph stage of the prey. The attack rate (α) and the handling time (Th) varied between the biological stages and also predatory mite species. The highest α (0.066 h−1) and the lowest Th (0.536 h) values were determined when the A. swirskii was fed on protonymph stage of E. orientalis. The numerical response curves were found to be similar to those of Type II functional response. The efficiency of conversion of ingested food (ECI) of the both predatory mite species females decreased on both tested stages when prey density increased. The highest and the lowest average daily mean number of eggs laid by E. scutalis was found as 0.20 and 1.40 when it fed on eggs and protonymphs of its prey, respectively.ConclusionBoth predatory mite species were evaluated as potential and promising biological control agents in the sustainable control of E. orientalis in citrus orchards.

Plant-Mediated Effects of Beneficial Microbes and a Plant Strengthener against Spider Mites in Tomato.

The two-spotted spider mite Tetranychus urticae is a polyphagous herbivore with a worldwide distribution, and is a serious pest in tomato and other crops. As an alternative to chemical pesticides, biological control with the release of natural enemies such as predatory mites represent an efficient method to control T. urticae in many crops, but not in tomato. Other biological control agents, such as beneficial microbes, as well as chemical compounds, which can act as plant defense elicitors that confer plant resistance against pests and pathogens, may prove promising biological solutions for the suppression of spider mite populations in tomato. Here, we assessed this hypothesis by recording the effects of a series of fungal and bacterial strains and the plant strengthener acibenzolar-s-methyl for their plant-mediated effects on T. urticae performance in two tomato cultivars. We found significant negative effects on the survival, egg production and spider mite feeding damage on plants inoculated with microbes or treated with the plant strengthener as compared to the control plants. Our results highlight the potential of beneficial microbes and plant strengtheners in spider mite suppression in addition to plant disease control.

Thermal Oviposition Performance of the Ladybird Stethorus gilvifrons Preying on Two-Spotted Spider Mites

The ladybird, Stethorus gilvifrons (Mulsant) (Coleoptera: Coccinellidae), is an important predator of two-spotted spider mites, Tetranychus urticae Koch (Acari: Tetranychidae), in southeastern Europe and western and southwestern Asia, such as Iran, India, and Turkey. To enhance forecasting the occurrence and performance of this predator in natural control and improve its usage in biological control, we evaluated and compared four non-linear oviposition models, i.e., Enkegaard, Analytis, Bieri-1, and Bieri-2. The models were validated by using data of age-specific fecundity of female S. gilvifrons at six constant temperatures (15, 20, 25, 27, 30, and 34 °C). All four models provided good fit quality to age-dependent oviposition at 15 to 30 °C (R2 0.67 to 0.94; R2adj 0.63 to 0.94) but had a poor fit at 34 °C (R2 0.33 to 0.40; R2adj 0.17 to 0.34). Within temperatures, the best performing models were Bieri-1 (R2), Bieri-2 (R2adj), and Analytis (RSS) at 15 °C, Bieri-1 at 27 °C, and Analytis at 20, 25, and 30 °C. Analytis was the best suited model across the wide temperature range tested (from 15 to 30 °C). The models presented here allow for prediction of the population dynamics of S. gilvifrons in field and greenhouse crops in temperate and subtropical climates.

Molecular Basis for the Selectivity of the Succinate Dehydrogenase Inhibitor Cyflumetofen between Pest and Predatory Mites.

Acaricides that act as inhibitors of the mitochondrial succinate dehydrogenase (SDHIs) provide excellent control of phytophagous mites but display limited toxicity to predatory mites and other beneficial organisms. However, the molecular mechanism of selectivity is not fully understood. Here, we first confirm that SDHI acaricides are over 10,000-fold more toxic to spider mites than predatory mites. Next, we show that differential penetration, pro-acaricide activation, or metabolism are most likely not the main reason for this selectivity. In contrast, the inhibition of AB-1 on the SDH target is approximately 200-fold more potent in spider mites compared to predatory mites, revealing strong target-site selectivity. Strikingly, a key motif associated with differential binding was identified and validated by gene editing in Drosophila. Our findings contribute to understanding the selectivity of SDHIs, which can be used for the rational design of selective acaricides in support of an integrated pest management.

Long-term effects of saffron pollen on development, reproduction and predation capacity of Neoseiulus cucumeris (Acari: Phytoseiidae)

Predatory phytoseiid mites as biocontrol agents are increasingly used in pest control programs across the globe, and Neoseiulus cucumeris (Oudemans) is one of them, which is a commercially available agent against various pests of greenhouse crops. This generalist predatory mite can feed on different foods and diets, including small arthropods and pollen. Feeding and reproducing on a pollen diet is a considerable characteristic of this predatory mite that facilitates the cost-effective production of large numbers of this predator so-called mass rearing. Therefore, the effects of saffron (Crocus sativus L.) pollen as an alternative food source on development and reproduction of N. cucumeris were determined over 20 successive generations. In addition, the predation ability of the nymphs and adults of N. cucumeris being switched to natural prey, Tetranychus urticae Koch after 10<sup>th</sup> and 20<sup>th</sup> generations was evaluated. The shortest and longest developmental time happened in the 1<sup>th</sup> and 5<sup>st</sup> generations, respectively. The predator in the 1<sup>st</sup> and 20<sup>th</sup> generations had a higher intrinsic rate of increase (r) (0.171 and 0.170 day<sup>-1</sup>, respectively) than other generations, while the 5<sup>th</sup> generation had the lowest value of this parameter. The development and fecundity of N. cucumeris was not significantly different when this predator switched to a diet of T. urticae. The results of this study revealed that rearing of N. cucumeris for 20 generations on saffron pollen did not affect the performance of the predator negatively and this alternative food source can be used for the mass rearing of N. cucumeris.

The quality assessment of Neoseiulus californicus (Phytoseiidae) reared on thorn apple pollen for 40 generations

ABSTRACT The predatory mite Neoseiulus californicus (McGregor) is an important biological control agent used to control some phytophagous mites. Developmental times, survival, and fecundity of this predator were assessed when fed on thorn apple (Datura stramonium L.) pollen grains over 40 sequential generations from G1 (reared on pollen in first generation) to G40 (reared on pollen for 40 generations). The predatory mites were obtained from a colony maintained for five generations on the two-spotted spider mite (TSSM) (Tetranychus urticae Koch) as prey. The predation capacity of the predatory mite on two-spotted spider mite was assessed in G1TSSM (without rearing on pollen) and G40TSSM (reared on pollen for 40 generations before transfer on T. urticae). The total developmental time of N. californicus varied among different generations, but there was no regular trend in the performance of the predatory mite reared over generations despite differences in population growth parameters. The intrinsic rate of increase (r) ranged from 0.156 day–1 in G2 to 0.229 day–1 in G20. The net predation rate (C 0), stable predation rate (), finite predation rate (), and transformation rate (Qp) of N. californicus on nymphal stages of the two-spotted spider mite showed no significant difference in G1TSSM and G40TSSM period. So, the quality of N. californicus reared on thorn apple pollen after 40 generations remained constant; indicating this pollen can be used as a suitable and cost-effective food source for the long-term rearing of N. californicus.

Differences of Moss Mites Communities at Different Vegetation Succession Stages in Subalpine Wetland (Jiulongchi, Fanjing Mountain), Southwest China

Fanjing Mountain, China, is a World Man and Biosphere Reserve, a World Natural Heritage Property, and a Nature Reserve in China. Mites communities have been reported from the Fanjing Mountain. Wetland moss microhabitats provide a unique habitat for mites, and our objective is to document moss mites communities in the subalpine wetlands of Fanjing Mountain (Jiulongchi), with a particular focus on trends in moss mites at different stages of vegetation succession in the wetlands, which have rarely been described, and the research will provide fundamental data for biodiversity conservation in the face of global climate change. The succession sequence from bryophyte (hygrophyte) to shrub (mesophyte or xerophyte) in the open area of Jiulongchi wetland successively includes Polytrichum commune Hedw. (PC), Eleocharis yokoscensis (Franch. et Sav.) Tang et-Cypers sp. (EY-C), Senecio faberii Hemsl (SF), and Indocalamus longiauritus Hand.-Mazz. (IL) four typical communities. In April 2016, we collected moss samples under the four typical communities mentioned above, and analyzed the difference of moss mite communities using PCA, Kruskal–Wallis nonparametric test, and ANOVA. The results showed the following: (1) A total of 9058 moss mites belonging to 49 genera in 3 orders and 69 families were captured in the four plant communities, with the moss mites Parachipteria, Fuscozetes, and Tectocepheus being the dominant taxa of moss mites in Jiulongchi wetland. The core taxa of moss mites at different successional stages were 12 genera, with IL having the largest number of exclusive taxa (20 genera). (2) The abundance of moss mites showed an overall increasing trend from PC to IL habitats, with the number of families and genera showing a pattern of IL > EY-C > SF > PC. The diversity index SF habitat possessed the maximum value, followed by IL, both of which were significantly different from PC. (3) The results of PCA analysis of moss mites showed that the mite community composition of PC habitats differed more from SF and IL, respectively, and less from EY-C. (4) There existed differences in the ecological taxa of predatory moss mites at different successional stages, with the Poronota group dominating the ecological taxa of oribatida. The research indicated that moss mites communities in subalpine wetlands were rich in species composition, and with the succession of vegetation from hygrophyte to mesophyte or xerophyte, the moss mites group as a whole develops in a direction favorable to its diversity, and the differences in moss mites ecological taxa also demonstrated the variability and complexity of the Jiulongchi wetland environment. This research presents the distribution pattern of moss mites in different vegetation succession stages in subtropical subalpine herbaceous wetlands. The moss mites evolution trend in response to climate-change-induced plant community succession needs further investigation.

Foraging behavior of Amblyseius swirskii (Acari: Phytoseiidae) feed on the invasive pest Tetranychus evansi (Acari: Tetranychidae) on tomato

The invasive tomato spider mite, Tetranychus evansi (Acari: Tetranychidae) is one of the major pests of the solanaceous plants worldwide. The phytoseiid predatory mite Amblyseius swirskii (Acari: Phytoseiidae) is one of the most commonly used predatory mites for augmentative biological control of several important pests in protected crops. Despite its frequent usage in a range of greenhouse crops including tomatoes, several biological characteristics and foraging behaviors of this predator such as functional and numerical responses, have not been studied on T. evansi. In this study, the functional and numerical responses of A. swirskii to four different biological stages (eggs, larvae, protonymphs and deutonymphs) of T. evansi were evaluated under laboratory conditions. The significantly negative P1 values and the type of functional response curves clearly indicate that A. swirskii exhibited a Type II functional response to T. evansi regardless of prey stage. The highest attack rate (α=0.070 h-1) and the shortest handling time (Th=0.426 h) were determined when the predator fed on protonymph and larva, respectively. The highest daily mean number of eggs (1.10±0.10) laid by A. swirskii was obtained at 120 egg density. No significant difference was determined in egg production of the predatory mite among different life stages within the same prey density except 10 prey density. In addition, there was also no difference among prey densities within the same biological stage, except egg stage. According to the results, A. swirskii may not be directly recommended for the biological control of T. evansi on tomato. However, when its inundative release is considered, it may help and improve the success of biological control of T. evansi, especially at early stages of infestations.

Expression and functional analysis of Niemann-Pick C2 gene in Phytoseiulus persimilis.

As a new protein class of semiochemical binding and transporting, Niemann-Pick proteins type C2 (NPC2) in arthropods have received more attentions in recent decade. However, the gene function has not been studied in phytoseiid mites with biocontrol potential. In the current study, we cloned a NPC2 gene PpNPC2a from the transcriptome of Phytoseiulus persimilis Athias-Henriot. By encoding 181 amino acids with a conserved ML domain, PpNPC2a was found a homolog of NPC2-1 in Galendromus occidentalis Nesbitt. We then measured the spatio-temporal expression of PpNPC2a in P. persimilis, and found the highest expression in female adults compared to other stages. Due to the tiny body size of predatory mites, we only examined tissue expressions in two sections: the anterior part (gnathosoma and the first pair of legs) and the posterior part (idiosoma without the first pair of legs). Higher transcription of PpNPC2a was found in the posterior part. To investigate the potential function of PpNPC2a in P. persimilis, we interfered gene expression in female adults by feeding dsRNA, which resulted in a decrease of relative expression by 59.1 and 78.2% after 24 and 72h, respectively. Compared with the control, dsNPC2a-treated P. persimilis were insensitive to the scent of leaves or plants infested by spider mites, suggesting a role of PpNPC2a in response to plant volatiles. However, the dsNPC2a-interfered mites could still respond to four representative compounds of herbivore-induced plant volatiles, including 4,8,12-trimethyl-1,3,7,11-tridecatetraene (TMTT), methyl salicylate (MeSA), β-caryophyllene and linalool. In short, our results indicated PpNPC2a may be involved in the chemosensory process of P. persimilis in response to whole-plant volatiles.

­Description of a new species of Stigmaeus (Acari: Stigmaeidae) with notes on species described from Northwest Iran

During a study of predatory mites in Urmia, Northwestern Iran, the female and male of a new species, Stigmaeus dokeri sp. nov. (Acari: Stigmaeidae), were collected from soil under oak trees. The specimens of the following species, S. malekii Haddad Irani-Nejad, Bagheri & Khanjani, 2006, S. boshroyehensis Khanjani, Izadi, Asali-Fayaz, Raisi, Rostami & Doğan, 2010, S. miandoabiensis Bagheri & Zarei, 2012 and S. marandiensis Bagheri & Ueckermann, 2011, were re-examined. We propose that S. boshroyehensis syn. nov. is a junior synonym of S. malekii. We also found S. miandoabiensis and S. marandiensis having bifurcate terminal eupathidium on palptarsus instead of tridentate in the original descriptions.

Berry species and crop management approaches affect species diversity and abundance of predatory mites (Acari: Phytoseiidae).

Berries comprise an economically important group of crops. Knowledge about their arthropod pests and biological control agents is important in the development of more efficient integrated pest management programs. Identification of potential biocontrol agents based solely on morphological attributes may be difficult and so molecular techniques should be incorporated. Here we studied the species diversity of predatory mites in the family Phytoseiidae, and how this diversity is affected by the berry species and crop management approaches, specifically pesticide application regimes. We sampled 15 orchards in the State of Michoacán, Mexico. Sites were selected based on berry species and pesticide regimes. Mite identification was achieved by combining morphological attributes and molecular techniques. Phytoseiidae diversity was compared amongst blackberry, raspberry and blueberry. Subsequently we studied the effect of berry species and pesticide regime on the abundance of the most prevalent phytoseiid species. We identified 11 species of phytoseiid mites. The greatest species diversity was found in raspberry, followed by blackberry and then blueberry. The most abundant species were Typhlodromalus peregrinus and Neoseiulus californicus. The abundance of T. peregrinus was significantly affected by pesticide application but not by berry species. In contrast, abundance of N. californicus was significantly affected by berry species but not by pesticide regime.

Ectoparasitism of the Flightless Drosophila melanogaster and D. hydei by the Mite Blattisocius mali (Acari: Blattisociidae).

Predatory mites dispersing by means of insects are often ectoparasites and may use various tactics to get onto the host, counteract its defenses, and diminish its survival. Blattisocius mali is a promising biological control agent which has been reported as transported by several drosophilid species. Our goal was to determine the type of relationship between this mite and fruit flies. We used flightless females of Drosophila melanogaster and D. hydei, which were commercially raised as live pet food. The predatory females mostly attacked the tarsi of the flies and then preferentially moved to the cervix or close to coxa III, where they eventually drilled their chelicerae and started feeding. Although both fly species used similar defensive tactics, more B. mali females did not attack D. hydei or did so with a delay, and a higher percentage of mites fell off the D. hydei tarsi during the first hour of observation. After 24 h, we noted the increased mortality of flies exposed to the presence of mites. Our study indicates the ectoparasitic relationship of B. mali with drosophilids. However, further research is needed to confirm the transport of this mite on wild D. hydei and D. melanogaster, both in the laboratory and under natural conditions.

Effects of far-red light on tritrophic interactions between the two-spotted spider mite (Tetranychus urticae) and the predatory mite Phytoseiulus persimilis on tomato.

The use of light-emitting diode (LED) lights in horticulture allows growers to adjust the light spectrum to optimize crop production and quality. However, changes in light quality can also influence plant-arthropod interactions, with possible consequences for pest management. The addition of far-red light has been shown to interfere with plant immunity, thereby increasing plant susceptibility to biotic stress and increasing pest performance. Far-red light also influences plant emission of volatile organic compounds (VOCs) and might thus influence tritrophic interactions with biological control agents. We investigated how far-red light influences the VOC-mediated attraction of the predatory mite Phytoseiulus persimilis to tomato plants infested with Tetranychus urticae, and its ability to control T. urticae populations. Far-red light significantly influences herbivore-induced VOC emissions of tomato plants, characterized by a change in relative abundance of terpenoids, but this did not influence the attraction of P. persimilis to herbivore-induced plants. Supplemental far-red light led to an increased population growth of T. urticae and increased numbers of P. persimilis. This resulted in a stronger suppression of T. urticae populations under supplemental far-red light, to similar T. urticae numbers as in control conditions without supplemental far-red light. We conclude that supplemental far-red light can change herbivore-induced VOC emissions but does not interfere with the attraction of the predator P. persimilis. Moreover, far-red light stimulates biological control of spider mites in glasshouse tomatoes due to increased population build-up of the biocontrol agent. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Intercropped Plants Provide a Reservoir of Predatory Mites in Coffee Crop

Conservation biological control of pests may be achieved using a variety of integrated strategies based on crop diversification. We investigated whether the insertion of the intercropped plants species (IPS) Inga edulis, Senna macranthera, and Varronia curassavica modified the abundance of mites, their feeding behavior, and the dissimilarity of predator and herbivore mites over a gradient of distance from the IPS on coffee. To accomplish this, we recorded the mite species on coffee plants along transects of 16 m extending from the IPS, including on the IPS. A total of 8946 specimens were sampled. Tenuipalpidae was the most abundant family on coffee, followed by Tydeidae, while Eriophyidae was the most abundant on the IPS, followed by Phytoseiidae. The abundance and richness of mites differed between their feeding behavior and distance. The dissimilarity of predators and herbivores increased along a gradient of distance. Furthermore, the IPS harbored several mite species and the diversity of predator and herbivore mites among the IPS was different. The findings suggest that the intercropped plant species can attract and serve as a reservoir of predatory mites on coffee crops, which could improve the biocontrol of pest mites on coffee.

Side effects of Zataria multiflora Boiss (Lamiaceae) essential oil on predation and life table parameters of Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae)

The predatory mite, Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) is one of the most promising candidates for biological control of some economically important mites and insect pests such as spider mites, whiteflies, and thrips. Western Flower Thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) is a severe economic pest for many crops in the world. In this study the lethal concentrations of Shirazicum thymus: Zataria multiflora Boiss (Lamiaceae) essential oil was calculated to the adult stage of the WFT. Side effects LC30 and LC50 of the essential oil were assessed on life table parameters and functional response of A. swirskii. Experiments were carried out in growth chambers at 25 ± 1 °C, 60 ± 10% RH, and 16: 8 h (Light: Dark) photoperiod. We utilized the age-stage, two-sex life table method to evaluate the life history features and population growth of A. swirskii on WFT. For assessing the functional response, the first instar of WFT was offered as prey to the adult female of A. swirskii with densities of 2, 4, 8, 16, 32, and 64. The LC50 concentration of the essential oil resulted in lower fecundity (15.05 eggs/female) in comparison with the control (19.8 eggs/female). The application of LC50 and LC30 concentrations also resulted in a significant decrease in net reproductive rate (R0) (8.9, 6.6, and 4.5 eggs per individuals), intrinsic rate of increase (rm) (0.116, 0.093, and 0.077 day -1), finite rate of increase (λ) (1.123, 1.097, and 1.079 day -1), but an increase in mean generation time (T) (18.5, 20.1, and 19.5 days) (for control, LC30, and LC50, applications, respectively). A type II functional response was detected for A. swirskii fed on WFT first instar in all treatments. Adult females of A.swirskii had the highest attack rate (a) (0.11± 0.01 h-1) and shortest handling time (1.61± 0.46h) on control treatment. In conclusion, although Z. multiflora essential oil had potential against F. occidentalis to be applied in integrated pest management programs, the lethal side effects of selected essential oil on the predatory mite, A. swirskii should be considered.

Survey and spatial distribution of tarsonemids and associated predators on coconut fruits

Tarsonemids are mites that can damage coconut fruits, leading to losses in crop yield and quality. In this study, a survey of tarsonemid species and associated predatory mites underneath the perianth of coconut was carried out on palms cultivated along the coast of northeastern Brazil, and their spatial distribution was studied in one of the cultivations, on fruits of different ages, to subsidize monitoring and management of pest species. Samples of fruits of different ages were collected from cultivation sites of 9 states, with sites ranging from a few km to a maximum of 100 km apart from one another. Three coconut palms were selected from each site, collecting 10 fruits with necrotic lesions similar to those caused by Steneotarsonemus species from each palm. The mites were collected, mounted and identified. For the analysis, a re-evaluation was done of the tarsonemids collected in similar surveys for mites in general on coconut fruits, as reported previously in the literature. Subsequently, a field in Igarassu (Pernambuco, Brazil) bearing fruits with symptoms caused by Steneotarsonemus species was selected, and a total of 943 fruits from 2–8-month-old bunches were collected for mite quantification and identification. Consequently, Steneotarsonemus concavuscutum Lofego and Gondim Jr., Steneotarsonemus furcatus De Leon, and four morphospecies of Tarsonemus were found under the perianths of coconut fruits growing along the coast of northeastern Brazil. In Igarassu, the most abundant tarsonemid was S. concavuscutum, representing 98.4% of all quantified mites. Populations of S. concavuscutum were observed in all fruit bunches, regardless of age (ranging from 19 to 167 mites/fruit), with the highest numbers occurring in the 6-month-old bunches. In this same geographic location, Neoseiulus baraki (Athias-Henriot) represented 99.0% of the predaceous phytoseiid mites, with a population ranging from 0.04 to 5.3 mites/fruit that attained the highest population levels on 7-month-old fruit bunches. The N. baraki population densities were positively correlated with the mean S. concavuscutum numbers.

New acaricide toxicity on tetranychus urticae koch, selectivity and side effect evaluations on the predatory mite phytoseiulus persimilis athias-henriot (Acari: Phytoseiidae)

The novel mode of action and newer pesticides product molecules is a promising component for agriculture management programs. For this argument some acaricide toxicity evaluations were completed on the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) in laboratory rearing for two generation under acaricide sublethal effect. Toxicity results showed that chlorfenapyr was the most toxic acaricide for Tetranychus urtica Koch and etoxazole was the lesast and for P. persimilis, etoxazole was the most toxic and fenproxymat was the least. Relative toxicity recorded was higher in etoxazole and fenproxymat (7.916 and 5.058 times) respectively. Selectivity data approved that abamectin was the most selective acaricide and etoxazole was the least (8.24 and 0.268) respectively. Effect on first generation of P. persimilis growth fertility and productivity declined, consequently, R0 and rm values where in LC25 attained values ranged from 0.59 to 0.66 for cyflumetofene and hexythiazox, ri data ranged from 0.29 to 0.36 for fenproxymate and cyflumetofene and R0 ranged from 0.53 to 6.0 for cyflumetofene and hexythiazox respectively. But in the second generation similar results attained because declined toxicity where rm in LC25 was from 0.93 and 1.13 for fenproxymat and etoxazole and in LC50 was 0.90 and 1.18 for cyflumetofene and hexythiazox respectively. A high effect on No of eggs /female/day produced, shortened in total time of the generation at LC50 level of treatment more than LC25, and sex ratio resulted more male number emerged than female. The high acaricide concentrations used can kill more T.urtica than P.persimilis.

Expression and functional characterization of odorant-binding protein2 in the predatory mite Neoseiulus barkeri.

Olfactionplays a crucial role for arthropods in foraging, mating, and oviposition. The odorant-binding protein (OBP) gene is considered one of the most important olfactory genes. However, little is known about its functions in predatory mites. Here, we used Neoseiulus barkeri, an important commercialized natural pest control, to explore the chemosensory characteristics of OBP. In this study, N.barkeri was attracted by methyl salicylate (MeSA) and showed higher crawling speeds under MeSA treatment. Then, we identified and cloned an OBP gene named Nbarobp2 and analyzed its expression profiles in the predatory mite. Nbarobp2 was 663bp, was highly expressed in larval and nymphal stages, and was significantly upregulated in N.barkeri under MeSA treatment. Nbarobp2 encoded 202 amino acid residues with a molecular weight of 23kDa (after removing the signal peptide). Sequence comparisons revealed that the OBPs in Arachnida shared 6 conserved cysteine sites, but were distinguishable from the OBPs of Insecta on the phylogenetic tree. RNA interference, Western blotting, and binding affinity assays further proved that Nbarobp2 was involved in volatile perception in predatory mites. This study shed light on the functional characteristics of OBPs in predatory mites, providing a new insight for better biological control.

Effects of temperature on life table parameters of a newly described phytoseiid predator, Neoseiulus neoagrestis (Acari: Phytoseiidae) fed on Tyrophagus putrescentiae (Acari: Acaridae)

The predatory mite, Neoseiulus neoagrestis Khaustov and Döker (Acari: Phytoseiidae), recently described as new species for science, but seems to have a great potential to be used in biological control. In this study, as a first step to determine the optimum temperature (between three temperatures tested) for its mass rearing, we studied its biological characteristics and life table parameters fed on Tyrophagus putrescentiae (Schrank) (Acari: Acaridae) at three different temperatures (20, 25, and 30 °C) under laboratory conditions. Results show that immature development, oviposition period as well as reproductive potential of this predator are significantly vary depending on the temperature. The immature developmental times and adult longevity for females, are ranged between 5.42 to 10.42 days and 39.88 to 74.12 days, based on the temperature, respectively. Average total number of eggs laid by per female at 25 °C (62.29) and 30 °C (58.65) are more or less similar but higher than that determined at 20 °C (41.46). The highest net reproductive rate (R<sub>0</sub>) is 29.066 (offspring/individual) at 25 °C. In addition, the highest intrinsic rate of natural increase (r) is 0.241 day<sup>-1</sup> at 30 °C. Furthermore, the highest finite rate of increase (λ = 1.272 day<sup>-1</sup>), and the shortest mean generation time (T = 13.416 days) and doubling time (DT = 2.874 days) are also determined at 30 °C. Our results demonstrate that N. neoagrestis successfully completed immature development, and can survive and reproduce at all tested temperatures. Nevertheless, a series of biological characteristics of this predator are differentially affected by the temperature. Finally, 25 °C and 30 °C seems to be more suitable for mass rearing of this predator on T . putrescentiae. Further studies should be conducted to determine biological characteristics and life table parameters of N. neoagrestis on several important pests such as spider mites, whiteflies and thrips.

The impact of entomophages on the population dynamics of major greenhouse cucumber pests

AbstractThe potentially effective use of entomophages against melon aphid, spider mite, tobacco thrips, and greenhouse whitefly has been demonstrated. The release rates of several entomophages have been proposed for protecting cucumber (Cucumis sativus L.) plants from the aforementioned pests. The predatory mites Amblyseius montdorensis Schicha, Neoseiulus cucumeris (Oudemans), and Amblyseius andersoni (Chant) were used to control the populations of thrips and greenhouse whiteflies. The dose of these entomophagous species applied was 8 to 10 individuals m–2 per plant every 3 wk. To fight spider mite, the predator Phytoseiulus persimilis Athias‐Henriot was used at the rate of 1 individual m–2 every 3 wk as a preventive measure. The parasitoid Aphidius colemani Viereck was released to suppress melon aphid (A. gossypii). The long‐term observations of the population dynamics of pests and the use of natural enemies to manage pests at the local level will enable us to adjust the dose of entomophages applied depending on the geographical location of the greenhouse facility, the regional climatic conditions, and weather conditions typical of certain years, etc. According to these factors, the results of this study are applicable to other greenhouse facilities with similar conditions. In future, the authors intend to elucidate an optimized method of using entomophagous species for farms located in warmer regions.