Journal of Pest Science最新文献

The fall armyworm, Spodoptera frugiperda, is a polyphagous pest in the Americas and a target of Bt crops. A study from 2011-2013 demonstrated practical resistance of S. frugiperda to Cry1F maize in the southeastern coastal region of the U.S. In this study, diet-overlay and leaf tissue bioassays were conducted to determine the susceptibility to four common Bt proteins in maize (Cry1F, Cry1A.105, Cry2Ab2, and Vip3Aa) in 23 S. frugiperda populations collected during 2021-2022 from seven southern U.S. states, including nine populations from the southeastern coastal region. In the diet-overlay bioassays with Cry1F, 22 populations were equally or more susceptible than a susceptible reference, with a single population showing an increased susceptibility ratio (LC₅₀ of field population/LC₅₀ of the susceptible strain) of 1.97. Susceptibility ratios of the 23 populations ranged from <0.15 to 4.67 for Cry1A.105 and <0.12 to 5.04 for Vip3Aa. Three populations exhibited an LC₅₀ >tenfold greater than the susceptible strain to Cry2Ab2. Altogether, the study did not provide evidence of practical resistance in S. frugiperda to the four Bt proteins. Instead, the results show that the recently collected populations were susceptible to Cry1F, Cry1A.105, and Vip3Aa. The Bt susceptibility was consistent across geographical locations and host plants. Results from the leaf tissue assays confirmed the findings of the diet-overlay bioassays. The reversed Cry1F susceptibility in S. frugiperda identified in this study represents the first case of documented practical resistance reverting to susceptible status in Bt crop-insect systems and thus has important implications for resistance management.

The Sterile Insect Technique (SIT) is a system based on the release of millions of sterile insects to prevent the reproduction of specific pest populations. However, to improve the efficacy of the SIT, sterile males must reach sexual maturity before being released to increase their probability of mating with wild females. Treatments with juvenile hormone (JH) analogs, such as pyriproxyfen (PPF), accelerate sexual maturity in sterile Anastrepha ludens (Loew) (Diptera: Tephritidae) males. We hypothesized that speeding up this life-history trait can affect male resistance to stressors such as chilling and starvation. In this study, we compared some quality control parameters of flies of two different strains, selected to resist desiccation (DR) and non-selected flies (NS), treated with PPF, and subsequently exposed to starvation and pre-release chilling periods. We used males that were treated with PPF after emergence. The results showed that, from 4 to 6 days of age, DR PPF-fed males mated less than NS PPF-fed males. DR and NS males obtained a similar number of copulations at 7 days of age. After chilling, survival was higher in DR than in NS males. In addition, NS males showed a slight advantage in number of copulations when they reached 5 days of age but not at 6 and 7 days of age. Chill-coma recovery time was longer in PPF-fed flies than in control flies. Moreover, PPF-fed flies obtained less copulations after exposure to chilling at 5 days of age compared to non-chilled flies. These results indicate that sexual maturity is accelerated in PPF-fed males, especially in NS flies. However, using PPF as a pre-release treatment for A. ludens results in a reduction in male quality, regardless of whether they are DR or NS.

Exotic natural enemies that are imported to control a target pest may attack non-target species or disrupt the performance of other natural enemies of the target that are already present. We evaluate possible interactions between three parasitoid species, the native Telenomus nizwaensis and the imported Trichogramma brassicae and Trichogramma evanescens, when presented with Deudorix livia host eggs under high-density laboratory conditions. Deudorix livia is a butterfly which is an economically damaging pest in the Omani pomegranate agro-ecosystem. Most (73.5% overall) of the observed parasitism was by T. nizwaensis. It performed best when presented with host eggs in the absence of either of the Trichogramma species. These imported species thus have some potential to disrupt suppression of the pest by the indigenous natural enemy under lower-density conditions in the field, and neither of them achieved high parasitism rates themselves (laboratory conditions: T. brassicae = 12.5%; T. evanescens = 18.5%; with no evidence for any parasitism of field-collected eggs). Future efforts in this agro-ecosystem would best be directed towards encouraging T. nizwaensis, rather than towards importation of Trichogramma. Screening for negative effects of natural enemies on the pest suppression provided by other natural enemies is recommended.

In this study, the objective was to develop a long-lasting mosquito repellent textile by synthesizing silk-based lavender oil microcapsules and applying them to cotton fabric. Lavender oil, derived from Lavandula angustifolia, was chosen as the plant-based material. The microcapsules’ morphology and the fabric’s surface were examined using optical and scanning electron microscopes. Dynamic light scattering was utilized to measure the capsule size and zeta potential. The mosquito repellent efficacy was evaluated through cage tests before and after multiple wash cycles and after exposure to different environments. A cytotoxicity assay was conducted on functionalized fabrics in order to assess their biocompatibility. Additionally, comfort properties such as breathability and water absorbency were assessed and compared to a control fabric. The results indicated that a higher concentration of lavender oil microcapsules (15 wt%) on the fabric exhibited excellent mosquito repellent efficacy (95.7%) prior to washing, which remained effective as 84.5% even after 40 washes. Furthermore, the functionalized fabric maintained its repellent properties following exposure to temperatures of 25 °C and 37 °C for 4 weeks. The cytotoxicity results indicated that the functionalized fabric exhibited non-toxic properties toward L929 cells, thereby confirming its favorable biocompatibility. This study successfully demonstrated the synthesis and application of silk-based lavender oil microcapsules on textiles, resulting in highly durable mosquito repellent fabrics effective against Aedes aegypti mosquitoes. These findings highlight the potential of this eco-friendly approach for developing effective and long-lasting mosquito repellent textiles.

While symbiont infections in invertebrates are widespread, their role in protecting hosts against natural enemies and chemical insecticides remains incompletely understood. Our study investigates the protective effects of Arsenophonus and Wolbachia, either individually or in co-infection, on Nilaparvata lugens against chemical insecticides. Our findings reveal that both Arsenophonus and Wolbachia confer protection against chemical insecticides, including triflumezopyrim, nitenpyram, and dinotefuran. However, these symbionts do not show protective effects against pymetrozine. Wolbachia infection leads to the up-regulation of the glutathione S-transferase (GST) gene GSTm2 and the P450 gene CYP6AY1. Uniquely, co-infection results in the up-regulation of the P450 gene CYP18A1. Furthermore, the stability of the co-infection is not constant, with its frequency decreasing from 93.3 to 73.1% over a nine-generation passage, while single infections remain consistently high (> 95%). Our study suggests that Wolbachia and Arsenophonus, both individually and in co-infection, provide protection against two commonly used chemical insecticides in N. lugens.

Endophytic and rhizosphere-competent entomopathogenic fungi (EF) are important plant bodyguards, although the mechanisms underlying this phenomenon are poorly understood. Therefore, we aimed to elucidate the roles of antibiosis (lethal and sublethal effects), and potential growth compensation (in response to leaf injury) in melon plants exposed to cotton leafworm. Plants were inoculated with one of three EF strains (EAMa 0158-Su Metarhizium brunneum strain or EABb 04/01-Tip and EABb 01/33-Su Beauveria bassiana strains) by either foliar spray, seed dressing or soil drenching and then challenged with either multiple short-term, or single long-term Spodoptera littoralis larval infestation. Endophytic colonization and relative expression of plant defense genes were tracked using molecular techniques alongside evaluation of antibiosis effects on S. littoralis and plant tolerance to larval-induced leaf injuries. Inoculated plants exhibited antibiosis and potential growth compensation in responses to various S. littoralis challenges, which resulted in increased fresh and dry weight, chlorophyll content, number of secondary branches and stem diameter. Furthermore, up-regulation in the relative expression of ethylene (ACO1, ACO3, EIN2, EIN3) and jasmonic acid (LOX2)-related genes were observed, with the endophytic B. bassiana- induction of ethylene and jasmonic acid production being higher in S. littoralis infested plants. Our findings strongly confirm the EF multifunctionality and the involvement of the Endophytic EF triggered melon defensive system induction in the antibiosis and compensatory growth to protect melon plants from pest damage.

To elucidate the deltamethrin resistance mechanism in Helicoverpa armigera, we explored mutations at the deltamethrin target site, genomic level variations between insecticide-susceptible and -resistant strains, and differences in gene expression patterns between the strains. Known pyrethroid resistance-associated point mutations within the voltage-gated sodium channel were undetected in the cDNA and gDNA of resistant strains or field populations. The whole-genome de novo assembly of a Korean-resistant strain was performed (GCA_026262555.1), and 13 genomes of susceptible and resistant individuals were re-sequenced using field populations. Approximately 3,369,837 variants (SNPs and indels) were compared with our reference H. armigera genome, and 1,032,689 variants were identified from open reading frames. A resistance-specific CYP3 subfamily gene with five variants (CYP321A1v1–v5) was identified in the resistant strains, indicating the potential role of these variants in resistance. RNA-seq analysis identified 36,720 transcripts from 45 Illumina RNA-seq datasets of the fatbody, gut, and the rest of the body. Differential gene expression analysis revealed some differently overexpressed detoxification enzyme genes in the resistant strains, particularly cytochrome P450 genes. This finding was consistent with the results of bioassay tests using PBO-based synergists that inhibit enzymes belong to cytochrome P450 family, further supporting the role of detoxification enzymes in resistance. Therefore, H. armigera may acquire deltamethrin resistance through a combination of actions, including the overexpression of various detoxification enzymes, such as CYP321A5 identified in this study may serve as a basis for understanding insecticide resistance at the molecular level and can be applied as diagnostic markers for resistance.

Sexually dimorphic traits are prevalent throughout the animal kingdom, extending to insects. In addition to sex-biased gene expression networks, these traits often involve variations in hormone levels. Juvenile hormone (JH), which is synthesized by corpora allata (CA), regulates development and reproduction in insects. However, there is limited understanding regarding sex-biased gene expression in CA and the sexually dimorphic functions of JH. We discovered sexual dimorphism in JH levels in cockroaches. To explore the underlying mechanism, we analyzed RNA-sequencing data from CA tissues in the adult females and males of the American cockroach, Periplaneta americana. Our investigation revealed significant variation in sex-biased gene expression, with female-biased genes primarily involved in cytochrome P450, glutathione S-transferase and peroxidase pathways, associating with resistance to environmental stress. Notably, exposure to the insecticide imidacloprid, injection of Escherichia coli and H₂O₂ led to a higher mortality rate in males, whereas females exhibited resistance. Importantly, the application of the JH analog methoprene following the injection of E. coli and H₂O₂ rescued survival and the expression of stress response-related genes in males. Furthermore, these stressors resulted in reduced JH biosynthesis in males, while females remained unaffected. In summary, our results reveal that sexually dimorphic JH levels and gene expression modulate stress responses in P. americana. These findings shed light on sex-specific responses to environmental stress, offering tailored strategies for pest control based on gender.

Oak dieback disease caused by the fungus Paecilomyces formosus threatens oak trees in the Zagros forests in western Iran. Various insects, such as wood-infesting beetles (Coleoptera), may play a role in dissemination of P. formosus. We collected larvae and adult insects from branch wood of oak trees with dieback symptoms in the Zagros forests. For larval identification, the mitochondrial gene cytochrome c oxidase I (COXI) was amplified by polymerase chain reaction (PCR). Fungal isolates from wood and insects collected from the sampled oaks were identified by morphology, acid production on creatine sucrose agar (CREA) medium, phylogeny of DNA sequence data for the β-tubulin gene and the internal transcribed spacer (ITS) rDNA. To detect P. formosus in larvae and adult insects, we used a nested PCR assay with the species-specific primer pairs PaMF and PaMR. The insects that most often tested positive for P. formosus were larvae of the buprestids Acmaeodera sp. and Chrysobothris affinis, and larvae of the cerambycid Trichoferus campestris. Adults of C. affinis and Calchaenesthes diversicolis (Cerambycidae), which were collected from within their galleries, also tested positive. Beetle larvae of Anthaxia sp. (Buprestidae), Latipalpis plana (Buprestidae), Monochamus sp. (Cerambycidae) and Crypticus gibbulus (Tenebrionidae) also tested positive. Larvae that tested negative for P. formosus were species of Cossidae (Lepidoptera), Elateridae (Coleoptera), Gasteruptiidae (Hymenoptera) and Syrphidae (Diptera). Future research is needed to determine whether any of these insects can serve as vectors of P. formosus. These results can be used to target-specific insects for monitoring.

Plant defense priming involves the release of air-borne volatile organic compounds (VOCs) by plants, serving to prepare defense-related mechanisms against herbivores and pathogens in adjacent receiver plants. While the concept of VOC-mediated plant defense priming for enhancing plant resistance has garnered considerable attention in the last two decades, it has yet to be fully realized and applied in practical crop protection. This review summarizes current research, examining the spectrum of VOC-mediated plant defense priming in terms of anti-herbivore or anti-pathogen properties, the cost–benefit implications for plants, and the influence of abiotic factors on the priming. Additionally, we explore two promising approaches within the framework of Integrated Pest Management (IPM): the implementation of companion sentinel intercropping and the application of synthetic VOCs. In conclusion, we propose future research directions for this promising area, anticipating that this review will stimulate efforts aimed at harnessing the effects of plant defense priming for the development of innovative pest management strategies and optimized IPM programs in crop protection.