Reduced insecticide susceptibility of the wheat aphid Sitobion miscanthi after infection by the secondary bacterial symbiont Hamiltonella defensa

• Published in: Pest management science 2021-04, Vol.77 (4), p.1936-1944
• Main Authors: Li, Qian, Sun, JingXuan, Qin, YaoGuo, Fan, Jia, Zhang, Yong, Tan, XiaoLing, Hou, MaoLin, Chen, JuLian
• Format: Article
• Language: English
• Subjects: Acetylcholinesterase; Agrochemicals; Animals; Aphidoidea; Aphids - genetics; Candidatus Hamiltonella defensa; Carboxylesterase; Chlorpyrifos; Detoxification; Enterobacteriaceae - genetics; Enzymatic activity; Enzyme activity; Farming systems; Fitness; Fluorescence; Fluorescence in situ hybridization; Glutathione; Glutathione transferase; Hamiltonella; Hamiltonella defensa; Hindgut; Imidacloprid; In Situ Hybridization, Fluorescence; Infections; Insecticide resistance; Insecticides; Insecticides - pharmacology; Insects; Low concentrations; Offspring; Pesticide resistance; Pesticides; Polymerase chain reaction; Sensitivity; Sitobion miscanthi; Symbionts; Symbiosis; Wheat
• ISSN: 1526-498X; 1526-4998
• DOI: 10.1002/ps.6221

BACKGROUND Bacterial symbionts in insects, especially aphids, have a major influence on host adaptation. We previously showed that infection with the secondary symbiont Hamiltonella defensa increases the fitness of the wheat aphid Sitobion miscanthi, yielding increases in fitness parameters such as adult weight and offspring number. However, whether H. defensa affects the sensitivity of host aphids to insecticides remains unknown. RESULTS We tested the effects of H. defensa on host aphid susceptibility to the insecticides chlorpyrifos methyl, imidacloprid, cyantraniliprole and acetamiprid. Our results showed that compared with Hamiltonella‐free aphid clones, Hamiltonella‐infected aphid clones exhibited lower sensitivity to most of the tested insecticides at low concentrations. Quantitative polymerase chain reaction showed that the density of H. defensa in the infected clones was slightly decreased at 24 h but then sharply increased until the late stage after treatment with the different insecticides. H. defensa in the host aphids was detected by fluorescence in situ hybridization and was localized to the aphid hindgut. Levels of the detoxification enzymes acetylcholinesterase, glutathione transferase and carboxylesterase were significantly higher in Hamiltonella‐infected clones than in Hamiltonella‐free clones. CONCLUSIONS The findings indicated that infection with H. defensa reduced aphid susceptibility to the investigated insecticides at low concentrations, potentially by increasing detoxification enzyme activity in the host. Therefore, symbiont‐mediated insecticide resistance should be taken into account when performing resistance‐monitoring studies. Studies of symbiont‐mediated insecticide resistance may enhance our understanding of the emergence of insecticide resistance in agricultural systems. © 2020 Society of Chemical Industry Bacterial symbionts in insects, especially aphids, have a major influence on host adaptation. The authors previously showed that infection with the secondary symbiont Hamiltonella defensa increases the fitness of the wheat aphid Sitobion miscanthi, yielding increases in fitness parameters such as adult weight and offspring number. However, whether H. defensa affects the susceptibility of host aphids to insecticides remains unknown. © 2020 Society of Chemical Industry