Performance and age-stage, two-sex life table of Neoseiulus californicus (Mcgregor) (Acari: Phytoseiidae) preying on Aculops lycopersici (Massee) (Acari: Eriophyidae) across tomato cultivars differing in leaf trichomes

Tetranychus urticae is a major agricultural pest mite whose rapid evolution of pesticide resistance necessitates innovative control strategies. RNA interference (RNAi) offers a promising alternative to chemical pesticides for its high specificity, efficiency, and environmental safety. Ecdysteroid signaling genes, which regulate molting and development in arthropods, represent potential RNAi targets for inducing lethal molting defects. This study investigated the roles of ecdysteroid signaling pathway genes in T. urticae molting and evaluated the potential of fusion double-stranded RNA (dsRNA) constructs targeting multiple genes to enhance RNAi efficacy. The expression profiling revealed that TuE74, TuECR, TuHR4, TuE93, and TuHR3 were highly expressed during the molting stage of T. urticae. RNAi-mediated silencing of these genes, particularly TuECR, TuHR3, TuHR4, and TuE74, caused distinct molting defects and high mortality. Fusion dsRNAs targeting combinations of these genes (ECR-HR3-HR4 or ECR-HR3-E74) achieved stronger and more coordinated gene silencing, lower median lethal concentration (LC50) and LC90 values than single-gene dsRNA (dsTuHR3), and exhibited cross-species efficacy against Tetranychus cinnabarinus and Tetranychus evansi. Importantly, the fusion dsRNAs showed no adverse effects on the predatory mite Neoseiulus californicus, supporting their biosafety. Spray-based delivery of fusion dsRNA significantly delayed molting, confirming its biological activity, although optimization of delivery efficiency is still required to achieve complete developmental arrest. The present study demonstrates that multi-target fusion dsRNA can substantially enhance RNAi efficacy, broaden control spectra across pest mite species, and maintain environmental safety. These results provide a molecular basis and applied framework for the development of next-generation RNAi-based acaricides for sustainable spider mite management. © 2026 Society of Chemical Industry.

Predatory mites are widely used to control major thrips pests in agricultural systems. The invasive Thrips parvispinus represents a challenge to economically important plants, with limited information available on the potential of predatory mites to control it. Eight commercially available predatory mites in the USA: Amblyseius swirskii, Amblyseius andersoni, Amblydromalus limonicus, Neoseiulus cucumeris, Neoseiulus californicus, Euseius degenerans, Anystis baccarum, and Stratiolaelaps scimitus; and four naturally occurring predatory mites in Florida: Proprioseiopsis ovatus, Neoseiulus longispinosus, Amblyseius largoensis, and Amblyseius adhatodae were evaluated. In choice experiments, predators were exposed to pairs of T. parvispinus stages (first instar-L1, second instar-L2, prepupa, pupa, and adult) to assess preference. Subsequent no-choice assays quantified predation and oviposition on the preferred stage: all phytoseiids were offered L1, P. ovatus prepupae, A. baccarum L2, and S. scimitus L2 or prepupae. Prey consumption and oviposition were recorded every 24h for four days. Neoseiulus longispinosus, A. largoensis, and A. adhatodae did not feed on T. parvispinus. The remaining phytoseiids preferred L1 over L2. Anystis baccarum preferred L2 and adult stages. Stratiolaelaps scimitus showed no stage preference, varying according to the offered stages. When offered L1, the highest predation was recorded for E. degenerans (5.78 L1/day), A. swirskii (4.14 L1/day), and N. cucumeris (3.23 L1/day). When offered L2, A. baccarum consumed 12.88 L2/day and S. scimitus 6.29 L2/day. All predators oviposited when feeding on T. parvispinus. Anystis baccarum produced one mass of 24 eggs, while the highest oviposition was observed for A. swirskii with 1.37 eggs/day. Our results suggest A. baccarum, S. scimitus, E. degenerans, N. cucumeris, and A. swirskii as the most promising predators of T. parvispinus.

Fungi of the genus Trichoderma have attracted attention because of their potential activity against phytophagous mites; however, information regarding their non-target effects on predatory mites remains limited. This study evaluated the effects of spore suspensions and secondary metabolites of Trichoderma afroharzianum Tr132 and Trichoderma virens Tvr2 on three predatory mite species widely used in biological control programs: Phytoseiulus persimilis, Neoseiulus californicus, and Amblyseius swirskii. Predator egg hatchability and adult mortality were assessed under laboratory conditions. Spore suspension treatments did not significantly affect egg hatchability, which remained high (97-99%) across all predator species. In contrast, secondary metabolites slightly reduced egg hatchability to 94-96%, compared with 99.5% in the control. Exposure to spore suspensions caused moderate mortality in adult predatory mites, increasing from 10 to 13% at 3 days post-application (dpa) to 15-19% at 6 dpa. Secondary metabolites produced higher mortality that increased over time, reaching 9-11% at 1 dpa, 17-18% at 3 dpa, and up to 22-25% at 6 dpa. Mortality responses were similar among predator species. Overall, Trichoderma applications had minimal effects on predator egg hatchability but caused moderate mortality in adult predatory mites, particularly following exposure to secondary metabolites. These findings highlight the importance of evaluating the compatibility of Trichoderma-based products with beneficial predatory mites before their integration into IPM programs.

ABSTRACT In Mexico, blueberries, raspberries, strawberries, and blackberries – commonly known as berries – rank second in fresh fruit production and export after avocado. However, phytophagous mites and other pests can cause significant economic losses and restrict trade. Proper identification of these pests is critical for implementing effective control measures, preventing pesticide resistance, and complying with quarantine and international trade standards. Despite their importance, there is still limited information regarding the mite species associated with each berry crop and their ecological roles within production systems. To address this gap, a study was conducted on the richness and biological diversity of mites in 20 municipalities distributed in seven major berry-producing states in México (Baja California, Colima, Estado de Mexico, Guanajuato, Jalisco, Michoacan, and Puebla). Species were identified based on morphological characteristics, and selected specimens were confirmed through sequencing of the cytochrome oxidase subunit I (COI) gene. We identified six mite species on blueberries, six on raspberries, four on strawberries, and eight on blackberries. Species abundance varied among the estates sampled, with Baja California showing the highest abundance and Puebla the lowest. Ecological diversity indices revealed that blackberries harboured the highest number of phytophagous, predatory, and saprophytic mites. The dominant phytophagous species Tetranychus urticae Koch and Diptacus rubuscolum Trinidad and Navia, along with the predatory mite Neoseiulus californicus McGregor. Additional species from the families Tarsonemidae, Tenuipalpidae, and Tydeidae were also identified.

Phytoseiid mites, as effective natural enemies, often experience various environmental stresses, especially extreme HTs under global warming and climate change. However, Neoseiulus californicus from the phytoseiid mite family could endure relatively HT (35-45 °C) exposure. To gain insights into its molecular mechanisms underlying heat adaptation, we conducted a comparative analysis of the transcriptomes exposed at 25 and 45 °C. There were 3117 and 7368 differentially expressed genes (DEGs) identified under the 0.5 and 4 h heat treatments, respectively. The functional enrichment analysis illustrated that DEGs were linked to "catalytic activity", "metabolic process", and the "Calcium signaling pathway". Further DEG annotation and analysis illustrated that the expression of proteins encoding heat shock proteins (HSPs) and protein turnover were significantly induced. We also identified the unigene DN1689_c0 encoding the HSP70 gene (NcHSP70), which exhibited the strongest transcriptional response to heat stress. NcHSP70 inhibition by RNAi suppression had a significant impact on the survival of N. californicus. The ATPase effect of the purified recombinant NcHSP70 protein after HT treatment was significantly elevated. These findings increase our comprehension of the complex molecular mechanisms underlying HT adaptation and determine the important role of NcHSP70 in the heat resistance of N. californicus.

The two-spotted spider mite, Tetranychus urticae Koch, is a significant pest in strawberry cultivation worldwide, causing substantial crop damage and economic losses. Biological control using predatory mites such as Amblyseius swirskii Athias-Henriot and Neoseiulus californicus (McGregor) is an essential component of integrated pest management (IPM) strategies. However, the efficacy of these natural enemies can be negatively affected by acaricide applications. This study assessed the sublethal effects of two acaricides; bromopropylate, a synthetic agent, and GC-Mite, a botanical formulation, on the life history and population growth parameters of A. swirskii and N. californicus feeding on T. urticae in strawberry crops. Acute toxicity assays demonstrated that both predatory mites exhibited significantly lower susceptibility to these acaricides than T. urticae, with A. swirskii showing the greatest resistance. Perinatal exposure to LC25 residue of bromopropylate and GC-Mite prolonged immature development, reduced adult longevity, and decreased fecundity in both predatory mite species. N. californicus experienced more pronounced negative effects, including marked declines in survival rates and reproductive output, whereas A. swirskii displayed greater resilience and more stable reproductive potential. Population growth parameters, such as the intrinsic rate of increase (r) and net reproductive rate (R0), declined significantly under acaricide treatments, with bromopropylate producing stronger adverse effects than GC-Mite. These results emphasize the relative compatibility of GC-Mite within IPM programs due to its lower toxicity to beneficial predatory mites. Careful selection and application of acaricides that minimize harm to natural enemies are crucial for sustainable management of T. urticae in strawberry cultivation.

Species sharing the same trophic level can interact not only through competition for resources but also through intraguild predation (IGP). Therefore, an important step toward implementing successful multiple predator releases in biological control strategies requires resolving how predators respond to the presence of heterogeneous competitors. This study examined the compatibility of two predatory mites, N. californicus and P. persimilis, which are both widely employed to suppress two-spotted spider mite populations in greenhouses and open fields. The experiments quantified the frequency and intensity of IGP across different developmental stages of these species on bean leaves, considering scenarios both with and without their shared prey being present. Additionally, a Y-tube olfactometer was employed to assess whether either predator avoided prey patches previously occupied by other heterospecifics, thereby providing insights into potential chemical cues that influence predator behavior. The results revealed that adult females of both predatory mite species predominantly targeted heterospecific eggs and larvae, whereas adults were largely avoided. In the absence of shared prey, N. californicus attacked 83% of the P. persimilis larvae and 37% of the eggs, whereas P. persimilis consumed 67% of the N. californicus eggs. The presence of shared prey reduced IGP risk by approximately 60%. Olfactometer assays revealed no significant avoidance of plants inhabited by heterospecifics at densities of 20 or 40 adults; both predators were similarly attracted to herbivore-induced volatiles. Generalized linear models indicated that host plant experience had a significant influence on the foraging response of N. californicus, whereas the effects of the feeding state weakened over time. Understanding predator foraging plasticity and responsiveness to chemical cues can help optimize biological control strategies in complex agroecosystems.

Tetranychus merganser and Oligonychus punicae are two pest mites that cause severe damage and economic losses in various crops in Mexico. Currently, the control of each pest primarily depends on the use of agrochemicals. However, these compounds harm the environment and the health of humans and mammals. Therefore, using biological predators to control populations of these mite species is an alternative to minimize the impact of these chemicals. Phytoseiulus persimilis is a specialist phytoseiid mite that feeds exclusively on Tetranychus species. Neoseiulus californicus is a generalist phytoseiid mite that feeds on different species of arthropods and pollen. However, P. persimilis and N. californicus have not been evaluated on T. merganser. The aim of this study was to evaluate the preference, predatory capacity and functional response of a single adult female and a 1:1 combination of both predators on the eggs and adult females of T. merganser and O. punicae. The results revealed that adult females of P. persimilis and N. californicus fed on the eggs and females of both T. merganser and O. punicae. P. persimilis exhibited higher levels of predation on T. merganser eggs and adult females, while N. californicus consumed more O. punicae eggs and adult females. Some differences in handling time (Th) and attack rate (a) were observed between and within phytoseiid species, but the functional response was consistently Type II. The differences in predatory capacity, Th, a, and preference were likely due to the varying lifestyles of the predators, predator size, the size of the prey offered (egg or adult female), and the species of prey provided.

Industrial hemp (Cannabis sativa subsp. sativa L.) is an emerging crop in Florida, generating $445 million in 2024. However, it is highly susceptible to acarine pests, including spider mites (Tetranychidae), broad mites (Tarsonemidae), and russet mites (Eriophyidae). Management options are limited due to a few federally registered products approved by the Florida Department of Agriculture and Consumer Services (FDACS-DPI). Laboratory bioassays were conducted on hemp leaf discs infested with Tetranychus urticae, T. gloveri, Polyphagotarsonemus latus, or Aculops cannabicola, and treated with biorational pesticides (citric acid, rosemary, thyme, sesame, garlic, and mineral oil) at maximum label rates. Citric acid and garlic oil were most efficacious against T. urticae, while garlic and thyme oils were most efficacious against the other species, causing over 80% mortality. Greenhouse trials confirmed the efficacy of citric acid and garlic oil against T. urticae, achieving 60–80% mortality within 24 h. Predatory mites (Amblyseius swirskii, A. andersoni, Neoseiulus californicus, Galendromus occidentalis) were evaluated against A. cannabicola, with A. swirskii showing the highest predation (≈20 adults/24 h) and reproduction. Compatibility tests indicated thyme and garlic oils did not significantly affect A. swirskii survival (>70% alive after 24 h). These findings support integrated pest management strategies for hemp acarine pests.

Panonychus citri (McGregor) (Acari: Tetranychidae) was evaluated under selective low-lethality acaricide regimes to assess multigenerational effects and compatibility with its predator Neoseiulus californicus (McGregor) (Acari: Phytoseiidae). Adult female P. citri (F 0 , parent generation) was exposed to lowlethal (LC 30 , ∼30 % lethal concentration) concentration of a novel acaricide (SYP-9625), abamectin, mineral oil, or vegetable oil. All treatments significantly reduced F 0 fecundity and survival, leading to suppressed population growth in the F 1 generation (offspring). Offspring from synthetic acaricide–treated mothers developed more slowly, whereas oil-based treatments did not prolong F 1 development but still shortened the offspring’s lifespan and reduced their fecundity. Binary mixtures of botanical oils with synthetic acaricides showed mostly synergistic toxicity against P. citri , yielding higher mortality than the respective single compounds. Integrating N. californicus with these low-toxicity treatments greatly improved control efficacy: predator–acaricide combinations caused faster and higher P. citri mortality and prevented pest resurgence. Importantly, the LC 30 treatments were largely innocuous to the predator. Neoseiulus californicus survival and oviposition were not significantly affected by these treatments (particularly in the oil-treated groups). However, abamectin residues did cause an initial repellent effect on the predators. Overall, selective acaricides and oils imposed transgenerational fitness costs on P. citri and, when combined with predation, achieved efficient mite suppression without harming the predator. These findings support the use of predator-compatible, low-lethality acaricides in integrated pest management of citrus mites. • Acaricides SYP-9625, abamectin, vegetable oil, and mineral oil showed varying toxicity against Panonychus citri and Neoseiulus californicus . • Low-lethality acaricides negatively affected P. citri reproduction and offspring development, especially synthetic ones. • Acaricide mixtures, like SYP-9625 + abamectin, displayed synergistic toxicity, improving P. citri control. • N. californicus enhanced P. citri control when combined with low-lethality acaricides, without harming predator survival. • Botanical oils (VO, ES) were more compatible with N. californicus , while abamectin repelled predators.

The citrus crop is severely damaged by the citrus red mite, Panonychus citri. The predatory mite Neoseiulus californicus is an effective natural enemy used for its biocontrol. To enhance predator efficiency, this study investigated the role of odorant-binding proteins in recognizing herbivore-induced plant volatiles (HIPVs). We identified two Niemann-Pick type C2 genes, NcNPC2-a and NcNPC2-b, which were highly expressed in adult females, particularly in the legs. RNAi-mediated silencing of NcNPC 2s impaired the mite's ability to locate HIPVs. Fluorescence binding assays and molecular docking confirmed that NcNPC2 proteins strongly bind undecylcyclohexane. Field trials using slow-release dispensers showed that HIPVs attracted predatory mites effectively within 2 m. These findings reveal that NcNPC2 proteins mediate the perception of HIPVs in N. californicus, providing insights for developing attractants to enhance biocontrol efficacy.

Mites and thrips often infest strawberry crops across the globe, with devastating outcomes for growers. In fact, Tetranychus urticae Koch and Scirtothrips dorsalis Hood are major pests of strawberries in Florida, USA, often infesting plants at the same time. Chemical control is ineffective because both pests have developed resistance to many pesticides; therefore, many growers are presently utilizing predatory mites. Currently, Amblyseius swirskii Anthis-Henriot is released for S. dorsalis and Phytoseiulus persimilis Athias-Henriot for T. urticae, but this dual-release strategy is costly and can reduce effectiveness since A. swirskii can prey on P. persimilis. This study evaluated whether Neoseiulus californicus (McGregor) could provide a single practical alternative for managing both pests. We assessed its feeding preference in laboratory using no-choice and choice tests where an adult predator was offered different life stages of T. urticae and larvae of S. dorsalis. Results showed that in no-choice tests, N. californicus consumed more T. urticae eggs compared to T. urticae adults. Also, S. dorsalis larvae and T. urticae deutonymphs were consumed in similar proportions. In choice tests, feeding shifted toward mobile prey with higher consumption of S. dorsalis larvae and T. urticae deutonymphs and adults. These results demonstrate that N. californicus is a flexible predator with potential to control both pests and should be investigated further for its potential as a cost-effective tool in strawberry pest management.

This study evaluated sublethal effects of the insecticides SYP-9625, abamectin, vegetable oil, and EnSpray 99 on the functional responses of the predatory mite Neoseiulus californicus, highlighting their potential disruption of biological control functions. When predators fed on all stages (eggs, immature, and adults) of Panonychus citri without insecticides, they exhibited a type II functional response. Sublethal exposure to SYP-9625 and vegetable oil altered the predator’s functional response curves without changing their response type compared to controls. Exposure to abamectin resulted in distinct functional response shifts, causing type I, type II, and type III responses when N. californicus fed on egg, immature, and adult stages of the pest, respectively. Exposure to EnSpray 99 led to a type I functional response in predators consuming immature and adult prey stages, characterized by non-significant linear parameters. The prey consumption rate was significantly impaired by abamectin, followed by EnSpray 99 and SYP-9625, compared to the control, while vegetable oil treatments increased predation rates by attracting predators. The fertility rate of N. californicus showed significant differences between vegetable oil and SYP-9625 treatments across impaired pest life stages. Abamectin and EnSpray 99 demonstrated the lowest compatibility with biological control, while vegetable oil increased predator attack rates and improved predator efficiency against P. citri. This study suggests that sublethal pesticide exposure can significantly alter predator behavior and efficiency. Integrated chemical-biological control strategies utilizing selective pesticides like vegetable oil show promise for citrus pest management but require further field validation.

ABSTRACT The study evaluated the impact of hunger levels on the prey consumption of Neoseiulus californicus (McGregor) sensu Athias-Henriot (Mesostigmata: Phytoseiidae) and its effectiveness in controlling Tetranychus urticae Koch (Trombidiformes: Tetranychidae) on bean plants. The effect of the hunger level on the consumption capacity of N. californicus was investigated using eggs, larvae, or nymphs of T. urticae. Gravid predatory mites (24–48 h old) were separately starved without water for 0, 24, 48, or 72 h before the bioassays. An adult female predator of each hunger level was then placed individually onto each bean leaf disc containing 30 eggs (0-24 h-old), 20 newly emerged larvae, or 20 newly emerged nymphs of T. urticae. After a 24 h feeding period, each predatory mite's prey consumption was separately counted for each stage. The effectiveness of N. californicus starved for 0, 24, 48, 72 h in controlling the T. urticae population was also determined on bean plants by comparing it to abamectin and an untreated control. The findings showed that hunger significantly reduced the consumption of prey eggs and larvae by N. californicus after 72 h of starvation. Conversely, N. californicus consumed more T. urticae nymphs at all starvation levels than when satiated. The results also showed that predators, deprived of food and water for 0, 24, and 48 h, effectively controlled the T. urticae population on bean plants, similar to abamectin. However, those without food and water for 72 h could not keep the population below the economic damage threshold during the experiment.

Tetranychus urticae Koch (Acari: Tetranychidae) is a widespread pest that causes significant crop losses. Although acaricides are commonly used for its control, the development of resistance often leads to control failures under field conditions. Therefore, there is a constant need for new compounds with novel modes of action. Novel neurotoxic insecticides targeting γ-aminobutyric acid (GABA) receptors, such as isoxazolines and meta-diamides, represent one of the most recent classes of insecticides. However, their toxicity to T. urticae, other tetranychid mites, and predatory mites remains poorly understood. The isoxazoline insecticides fluralaner and isocycloseram showed very high toxicity to all T. urticae populations, with LC50 values ranging from 0.53 to 2.64mg a.i./L and 0.04 to 0.26mg a.i./L, respectively. Isocycloseram also caused 100% mortality in two other phytophagous mite species, Eutetranychus orientalis and Bryobia rubrioculus, at field application rates (30mg a.i./L). In contrast, the meta-diamide broflanilide exhibited no toxicity against any of the tested phytophagous mites at the recommended field rate (20mg a.i./L) and even at very high concentrations (5000mg a.i./L), the mortality rate remained below 65% in all T. urticae populations except one. On the other hand, both isocycloseram and broflanilide, at their field rates, exhibited strong side effects ‒causing 100% mortality‒ on three predatory mite species: Phytoseiulus persimilis, Neoseiulus californicus, and Amblyseius swirskii. These findings highlight the potential of novel insecticides for mite control, while also emphasizing the importance of evaluating their non-target effects to support the development of sustainable pest management strategies.

Biological control and host plant resistance are frequently integrated in many reliable integrated pest management (IPM) strategies. However, the integration of these strategies can influence the interactions among plants, herbivores, and their natural enemies. Differences in the quality of a host plant may positively or negatively influence the strength of the top-down forces. In this study, the effects of seven glasshouse pepper cultivars, including the susceptible cultivars (Lumos and AD90), semi-resistant cultivar (Clavesol), and resistant cultivars (Chidem, Sympathy, Sunset, and AG50) on the biological performance and predation capacity of the predatory mite Neoseiulus californicus (McGregor) when feeding on different stages of the broad mite Polyphagotarsonemus latus (Banks) were investigated under controlled conditions. Significant differences were observed in the biological performance and predation capacity of the predator on different cultivars. The intrinsic rate of increase (r) varied from 0.079 d-1 in Sunset (resistant) to 0.134 d-1 in Lumos (susceptible). Significant differences were also observed among the resistant cultivars, which Sunset had a higher negative impact on the population growth parameters (r, gross reproductive rate (GRR), and net reproductive rate (R0)) of the predator compared with the other cultivars. In addition, the semi-resistant cultivar of Clavesol performed similar to the susceptible cultivars. The R0 of the predator varied from 3.20 eggs/individual in Sunset to 6.94 eggs/individual in Lumos. The highest value of the net predation rate (C0) (1168 prey/predator), finite predation rate (ω) (30.09 prey/predator), and stable predation rate (ψ) (27.81 prey/predator) were observed on Sympathy (resistant), Sunset (resistant), and Sunset (resistant), respectively. CONCLUSION Although population growth potential of N. californicus was higher on the susceptible cultivars compared with the resistant and the semi-resistant ones, the predator's predation capacity was notably higher on the resistant and semi-resistant cultivars compared with the susceptible ones. The resistant cultivars also showed varying degrees of resistance, where the highest negative impact on the life table parameters of the predatory mite was observed when N. californicus fed on Polyphagotarsonemus latus reared on the Sunset cultivar. However, the resistant cultivars and N. californicus can improve the broad mite management program on glasshouse peppers despite some negative impacts on the predator. © 2025 Society of Chemical Industry.

ABSTRACT The Perseae mite, Oligonychus perseae Tuttle, Baker & Ababatiello (Acari: Tetranychidae), constitutes a significant threat to avocado crops in the Canary Islands, often resulting in substantial economic losses for growers. Despite efforts to control this pest through the release of phytoseiid predators, particularly Neoseiulus californicus (McGregor), satisfactory control has not been achieved. The prevalence of the phytoseiid species Euseius stipulatus (Athias-Henriot) in avocado orchards suggests its potential as a biological control agent for managing O. perseae populations. This study evaluated the impact of diet, specifically Carpobrotus edulis pollen and O. perseae eggs, on the life cycle of E. stipulatus. The predator exhibited a notable preference for consuming eggs during its developmental stages. A type II functional response was observed in the predator, where the number of eggs consumed increased proportionally with the quantity offered. While E. stipulatus demonstrated the ability to sustain itself and reproduce by preying on O. perseae eggs, certain parameters such as longevity, fecundity, and oviposition time were significantly enhanced by pollen.

A predator-release device with a waterproof shelter protecting a slow-release sachet containing Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) has become commercially available for spider mite control. In this study, we examined the population dynamics of spider mites and phytoseiid mites in a Japanese pear greenhouse equipped with predator-release devices during 2019–2021. The presence of commercialized N. californicus on pear leaves before noticeable spider mite occurrence was confirmed during each of the survey years. Our results demonstrated that the spider mite density remained low for the first two years, but a notable spider mite outbreak occurred in the final year, presumably because a fungicide highly toxic to N. californicus was used before the release of the commercialized N. californicus individuals. Results also demonstrated that Neoseiulus barkeri Hughes (Acari: Phytoseiidae), the second dominant phytoseiid mite species, increased its relative proportion in the summer and possibly affected spider mite occurrence through intraguild predation. These results suggest that avoiding harmful pesticides and elucidating interactions among phytoseiid mite species are crucially important for more effective utilization of commercialized N. californicus for spider mite control.

Gene editing to enhance pesticide resistance in a beneficial predatory mite.