The relationships among six species of the Amiota taurusata Takada, Beppu, & Toda (Diptera: Drosophilidae) species group were investigated based on DNA sequence data of the mitochondrial NADH dehydrogenase subunit 2 ( ND2) gene, using three species of the genus Amiota as outgroups. A mitochondrial gene, cytochrome c oxidase I ( COI), can be used to discriminate between species of the taurusata group. Two new species are described from South China: A. protuberantis Shao et Chen, sp. nov. and A. shennongi Shao et Chen, sp. nov. A key to all the species of the taurusata group based on morphological characters is provided.

The fall armyworm (FAW) Spodoptera frugiperda is a notorious pest, causing severe crop damage worldwide and prompting effective prevention and control. Over-reliance on and intensive use of insecticides are prone to leading to the rapid evolution of insecticide resistance, urging rational insecticide application. One effective way of rational insecticide application is to apply insecticides of different modes of action in combination or supplemented with adjuvants. In this study, we assessed the efficacies of two individual insecticides, emamectin benzoate (EB) and chlorantraniliprole (CT), and their mixture, supplemented with and without the oil adjuvant Jijian^® to control FAW in laboratory bioassays and a field trial. Both EB and CT showed high toxicities to FAW. The EB × CT mixture at a mass ratio of 9:1 yielded a remarkable synergistic effect, with the co-toxicity coefficient (CTC) being 239.38 and the median lethal concentration (LC50) being 0.177 mg/L. In leaf-spray bioassays, the addition of the adjuvant reduced the LC50 values of both the individual insecticides and the EB × CT mixture by more than 59%, significantly improving the efficacies. The field trial confirmed the synergistic effects of the adjuvant, which reduced the amount of EB × CT mixture by 80%. This study provides an effective and promising insecticide–adjuvant mixture to control S. frugiperda.

Chemical control is the main method used to manage the oriental fruit fly (Bactrocera dorsalis) in orchards. However, the oriental fruit fly has gradually developed resistance to multiple insecticides, posing significant challenges for pest resistance management. This study investigated changes in insecticide resistance in oriental fruit flies under different selection pressures. We identified resistance-related genes and their mutation sites using cDNA probes. Our results showed that resistance to trichlorfon decreased significantly in the absence of selection pressure. However, resistance increased when selection pressures were applied every 30 or 60 days. Although the resistance ratio showed a decreasing trend at every 90 and 120 days, a risk of a rebound remained. A large number of homologous sequences were identified in the suppression subtractive hybridization library of insecticide-resistant strains. Resistance to trichlorfon and alphamethrin primarily involves detoxification and metabolic genes, which are often associated with cross-resistance. A single gene may detoxify multiple pesticides, leading to cross-resistance. The four acetylcholinesterase mutations identified in this study are consistent with previous research findings. Moreover, resistance results from the combined action of multiple genes. Based on these findings, this study recommends avoiding continuous use of trichlorfon and maintaining an interval of more than 80 days between applications. It also emphasizes the importance of incorporating pesticide application intervals into integrated pest management strategies. This study provides a theoretical foundation for delaying resistance development in the oriental fruit fly, offers guidance on proper pesticide application intervals in the field, and contributes practical insights for pest resistance management.

Rice volatiles play a crucial role in mediating resistance to the brown planthopper (Nilaparvata lugens Stål, Hemiptera: Delphacidae), a major pest of rice crops. In this study, we analyzed secondary metabolites from rice plants to identify compounds associated with insect behavior. A total of 31 volatile metabolites were detected, among which 16 differed significantly between 51 resistant or susceptible varieties. Fifteen volatiles were more abundant in susceptible plants, while one was enriched in resistant varieties. Electrophysiological (EAG) and Y-tube olfactometer assays revealed that both male and female adults exhibited positive chemotaxis toward five volatiles: Cyclohexanone, 2,2,6-trimethyl-; 3-Cyclohexen-1-one, 3,5,5-trimethyl-; (+)-Isomenthol; Benzoic acid, 2-hydroxy-, methyl ester; and 2-Methoxy-4-vinylphenol. In contrast, male adults were repelled by Benzaldehyde, 3-ethyl-, and 3-Buten-2-one, 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-. These results indicate that characteristic volatiles serve as functional cues for host selection and may act as phytochemical markers for assessing rice resistance. The findings provide new insights into plant–insect chemical interactions and suggest potential strategies for environmentally friendly pest management, including the use of attractant- or repellent-based approaches and breeding for optimized volatile profiles to control N. lugens.