Journal of Pest Science最新文献

The Hyphantria cunea (Lepidoptera: Erebidae), a significant invasive pest, has inflicted substantial economic damage on global agriculture and forestry. Plant-derived pesticides formulated as microcapsules present promising prospects for pest management. This study identified key insecticidal compounds from Albizia kalkora (Leguminosae: Rosales), a low-preference host for H. cunea, and developed them into microencapsulated insecticides. Esculetin, pinpointed as the principal anti-insect compound in A. kalkora, exhibited strongest toxicity against H. cunea, manifesting as reduced larval body weight, elevated mortality rates, and altered expression of genes regulating growth. The compound also depleted larval nutrient reserves and suppressed critical gene expression in the tricarboxylic acid cycle and glycolytic pathways. Despite the activation of detoxification and antioxidant systems in esculetin-treated larvae, oxidative damage remained unresolved. Microcapsules containing esculetin, fabricated via the single coagulation method, demonstrated superior slow-release behavior, thermal stability, and resistance to photodegradation. Laboratory and field trials confirmed that esculetin microcapsules exerted comparable or greater toxic effects than unformulated esculetin on larval growth, survival, oxidative stress, nutrient content, and energy metabolism. Additionally, esculetin microcapsules were categorized as low-toxicity pesticides, with negligible adverse effects on Danio rerio (Cyprinidae: Cypriniformes) and Arma chinensis (Hemiptera: Pentatomidae). Thus, microencapsulated insecticides utilizing esculetin as the active component provide an effective, safe, and environmentally sustainable strategy for managing H. cunea infestations.

The lepidopteran Spodoptera frugiperda, a key pest in maize production, has developed resistance to various active ingredients. In this context, botanical insecticides such as essential oils (EOs) offer promising alternative, particularly when integrated with biological control strategies. Baccharis EOs demonstrates to be a promising botanical insecticide for the control of agricultural pests. This study aimed to evaluate the bioactivity of EOs from Baccharis articulata, Baccharis calvescens, Baccharis dracunculifolia, Baccharis milleflora, and Baccharis uncinella and its effects in biomarkers against S. frugiperda, as well as their effects on the parasitoid Telenomus remus. The chemical composition of the EOs was identified through gas chromatography–mass spectrometry. Insecticidal activity was assessed via contact and ingestion assays, with toxicity evaluated using biochemical markers. Additionally, the impact of the EOs on different developmental stages of T. remus was investigated. The number of compounds identified in the EOs ranged from seven in B. articulata to 27 in B. milleflora. Toxicity levels varied across Baccharis species, with B. articulata exhibiting the lowest LC₅₀ value (0.67%) and B. calvescens exhibiting the highest LC₉₀ value (2.05%). Baccharis EOs showed evidence of neurotoxicity and lipid peroxidation damage in S. frugiperda. Notably, B. calvescens and B. milleflora caused no mortality in T. remus eggs and pupae but exhibited repellency rates of 40–55%. Baccharis species have significant insecticidal activity against S. frugiperda, with neurotoxic effects, while demonstrating selectivity for T. remus. These findings highlight Baccharis EOs as promising botanical insecticides that align with sustainable agricultural production models, offering an alternative to synthetic insecticides.

Increasing restrictions on synthetic pesticides due to environmental and health concerns have driven the search for alternative environmentally friendly pest management strategies. Essential oils (EOs) from plants like garlic (Allium sativum), clove (Syzygium aromaticum), and eucalyptus (Eucalyptus camaldulensis) have shown promise as bioinsecticides. However, their volatility, low water solubility, and short persistence limit their practical application in Integrated Pest Management programs. To address these challenges, we developed nano-emulsions of these EOs using a high-pressure microfluidization technique, achieving stable formulations with nano-sized droplets (< 200 nm) and optimal polydispersity index and zeta potential values. The insecticidal efficacy of these EO-based nano-emulsions was tested against the invasive citrus pest Delottococcus aberiae, with garlic nano-emulsion (GNE) exhibiting the highest mortality (100% within 24 h), significantly outperforming clove and eucalyptus formulations. GNE exhibited a dose–response mortality against D. aberiae while demonstrating no toxicity (100% of survival) toward Cryptolaemus montrouzieri and no phytotoxicity on citrus plants. Moreover, gene expression analysis revealed that GNE application triggered the overexpression of key genes involved in plant defense pathways, including ICS2, NPR1, PAL, and MYC2, suggesting the activation of both salicylic acid and jasmonic acid signaling pathways. This dual action—direct pest control and enhancement of plant defenses—positions GNE as a powerful tool in sustainable citrus pest management, with potential applications in real-world pest control. The study underscores the potential of EO-based nano-emulsions as a safe, effective, and environmentally sound alternative to chemical insecticides.

The invasion of fall armyworm Spodoptera frugiperda poses a significant threat to the maize production of smallholder farmers in Asia and Africa. Bt maize is an effective measure for controlling this pest, but resistance management strategies tailored to the smallholder farming systems in the old world remain poorly understood. Surveys conducted from 2021 to 2022 in key infestation regions of Yunnan and Guangxi, China, revealed that an average administrative village includes 633 households, each cultivating 0.22 ha of maize per season, with 95.68% of fields smaller than 0.33 ha. Laboratory and field studies indicated that the high dispersal ability of fall armyworm larvae facilitated frequent larval movement between Bt and non-Bt maize within seed mixtures and structured refuges in smallholder farming systems. Resistance evolution models showed that establishing structured refuges covering 10–20% of households at the village level significantly slowed resistance development. This study proposes a village-based structured refuge strategy, proportionally allocated according to household distribution. The strategy is simple and feasible for smallholder farming systems in developing countries, offering a novel approach for managing resistance to Bt maize in fall armyworms.

Trehalase (TRE) is an important enzyme that is responsible for trehalose hydrolysis. However, the effect of NLTRE on the reproduction of Nilaparvata lugens has not been clearly reported. To comprehensively evaluate the pest control potential of NLTRE, this study analyzed the effect of NLTRE on female reproduction of N. lugens by inhibiting TRE with dsTREs injection at mRNA level and validamycin injection at protein level, respectively. The results showed that validamycin not only significantly reduced the female body weight, but also extended the preoviposition time, but dsTREs had no significant effect on these phenotypes. Besides, validamycin significantly inhibited the ovarian development of females in the early stage, while dsTREs affected the ovarian development in the later stage. However, both two treatments have extremely significantly reduced the total number of eggs laid by female, and the egg hatchability also was extremely significantly decreased, likely due to the destruction of chitin components in egg shells. Therefore, TRE inhibition can decrease the fecundity of N. lugens female, which suggest that TRE is a potential pest control target.

The metabolic cooperation for the phenylalanine synthesis between the host and its obligate symbiont is widespread in hemipteran insects. However, the mechanisms underlying phenylalanine synthesis and its role in hemipteran insects are largely unknown. Our previous study indicates that the whitefly Bemisia tabaci glutamate–oxaloacetate transaminase gene GOT2 compensates for tyrB missing from Portiera. Here, we found that the whitefly GOT2 and Portiera can cooperate for the synthesis of phenylalanine mainly by silencing GOT2. We further revealed that the phenylalanine synthesized by whitefly–Portiera symbiosis promotes cuticle formation on adult whiteflies. Then, we demonstrated that repression of phenylalanine synthesis by silencing whitefly GOT2 does not significantly increase the whitefly mortality under high temperature and low humidity conditions, but it enhances the whitefly mortality when whiteflies were infected with the entomopathogenic fungi Beauveria bassiana. Our results provide experimental evidence on how symbiosis contributes to adult whitefly cuticle formation, revealing parallel histories of the phenylalanine synthesized by the host and its obligate symbiont facilitated cuticle formation in insects housing the bacteriocyte symbionts. This study indicates that the phenylalanine synthesized by insect–bacteria symbiosis may confer the insect adaptation to entomopathogenic fungi. Our findings will also help us to develop an insect symbiosis disruption strategy for pest control.

Human-induced changes, such as climate variability and escalating anthropogenic pressures, profoundly impact species distribution, dispersal, and competitive interactions worldwide. In the Neotropical region, the expansion of rice cultivation under these conditions has facilitated the spread of species within the rice stink bug complex, notably Oebalus species. Among these species, Oebalus pugnax prevails in the United States (US) and O. poecilus in Neotropical America co-occurring with O. ypsilongriseus, which was recently introduced into the US. This study explores the determinants and predictive variables influencing the occurrence and overlap of rice stink bugs, utilizing maximum entropy species distribution modeling to project their potential distribution. Precipitation and temperature were identified as pivotal factors shaping the ecological niche of O. pugnax in the US, while sensitivity to dry spells appears instrumental in the niche specialization of Neotropical species such as O. ypsilongriseus and O. poecilus. Notably, O. pugnax shows potential for establishment in South America, whereas O. ypsilongriseus and O. poecilus exhibit potential to establish in the southeastern US. Prospects that may aggravate concerns with their potential economic losses under the current trends on global climate changes. Although bioclimate-based distribution modeling provides valuable insights into habitat suitability and species distribution, future research should focus on delineating thermal and humidity thresholds for their development, as well as elucidating interspecific relationships. These endeavors are essential for enhancing our comprehension of their distribution dynamics and assisting in the design of effective pest management strategies, taking advantage of the biological peculiarities and susceptibility to different control methods by each individual species.

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), is a highly polyphagous agricultural pest that seriously threatens food production and agricultural development. Lufenuron is widely used because of its good control effect and safety to nontarget organisms. However, due to the continuous application of lufenuron and the evolution of insect resistance mechanisms, the potential of S. frugiperda developing resistance to lufenuron is increasing. Insect gut bacteria play an important role in insecticide resistance. We established a germ-free (GF) rearing protocol and cultured monoassociated gnotobiotic S. frugiperda with 20 different bacteria to explore the possible mechanisms of gut bacteria resistance in insects. After the larvae were exposed to lufenuron, Klebsiella C3 was screened, which could significantly change the resistance of larvae to lufenuron. Moreover, chitin synthesis and metabolism in larvae fed with Klebsiella C3 were significantly affected. The liquid chromatography results showed that Klebsiella C3 could not directly degrade lufenuron. Nontargeted metabolomics analysis revealed that the intervention of Klebsiella C3 resulted in the production of different metabolites by S. frugiperda, which affected the associated metabolic pathways. These changes in substances may be responsible for the altered sensitivity of S. frugiperda to lufenuron. Taken together, our study investigated how intestinal bacteria influence the resistance of S. frugiperda against insecticides. This research offers new insights for developing preventive and control strategies against this key pest.

Insecticide resistance in pest control poses a threat to agricultural production and human health. Numerous insect species express genes coding for detoxification enzymes that have broad substrate promiscuity thus conferring resistance to various insecticides. However, whether the homologs of these genes play similar roles in resistance phenotypes of closely related species remains largely unclear. Therefore, this study compares the resistance profiles of three major rice planthopper species (Delphacidae) (Laodelphax striatellus, Nilaparvata lugens, and Sogatella furcifera) based on the metabolic activity of their cytochrome P450s. Genome-wide analyses resulted in 68, 70, and 64 P450 genes in L. striatellus, N. lugens, and S. furcifera, respectively. Phylogenetic analyses among these genes found that most resistance-related genes in one species had homologs in other planthopper species. The most resistance-relevant orthogroup (CYP6ERs) showed higher evolutionary instability than most other groups. RNAi and in vitro metabolism assays revealed that CYP6ERs confers more divergent insecticide resistance profiles among planthopper species than the other two major resistance-related P450 subfamilies (CYP6AYs and CYP4C61s). Alphafold-based structural predictions and alignments suggested that P450 orthogroups with higher phylogenetic instability tended to have less structural similarities, resulting in more divergent metabolic profiles. This relationship was also in silico validated on Aphidae aphids and Lepidoptera noctuids. This study proposes combined phylogenetic and toxicogenomic analyses for understanding CYPome-based insecticide resistance convergency and divergency among closely related pests. These findings may improve the accuracy and rationality of chemical pest control.

The fall armyworm, Spodoptera frugiperda, a significant pest, has spread to many countries in Africa and Asia in recent years, causing substantial losses in corn production. From 2019 to 2024, we monitored the host strain of S. frugiperda in various regions in Jiangsu Province, China. The result showed that only COIRS-TpiRS and COIRS-TpiCS strains were present in corn during 2019 and 2020. In 2021, COIRS-TpiRS, COIRS-TpiCS and COICS-TpiCS strains were detected in both corn and rice. By 2024, all the three strains were found exclusively in corn. Notably, the proportion of COIRS-TpiRS strain increased from 2019 to 2021, but declined in 2024. Experimental data demonstrated that COIRS-TpiRS had higher fitness on rice than on corn, and showed a preference for damaging and ovipositing on rice. However, the occurrence of S. frugiperda in rice paddies remains rare, suggesting that it is unlikely to become a significant threat to rice production in China in the coming years without change in rice planting pattern.