The insecticidal activity and mechanism of tebuconazole onNilaparvata lugens(Stål)

Abstract

AbstractBACKGROUNDPrevious studies have shown that fungicides have insecticidal activity that can potentially be used as an insecticide resistance management strategy in the brown planthopperNilaparvata lugens(Stål). However, the mechanism that induces mortality ofN. lugensremains elusive.RESULTSIn the present study, the insecticidal activities of 14 fungicides againstN. lugenswere determined, of which tebuconazole had the highest insecticidal activity compared with the other fungicides. Furthermore, tebuconazole significantly inhibited the expression of the chitin synthase geneNlCHS1; the chitinase genesNlCht1,NlCht5,NlCht7,NlCht9, andNlCht10; and theβ‐N‐acetylhexosaminidase genesNlHex3,NlHex4,NlHex5andNlHex6; it significantly suppressed the expression of ecdysteroid biosynthetic genes as well, includingSDR,CYP307A2,CYP307B1,CYP306A2,CYP302A1,CYP315A1andCYP314A1ofN. lugens. Additionally, tebuconazole affected the diversity, structure, composition, and function of the symbiotic fungi ofN. lugens, as well as the relative abundance of saprophytes and pathogens, suggesting that tebuconazole reshapes the diversity and function of symbiotic fungi ofN. lugens.CONCLUSIONOur findings illustrate the insecticidal mechanism of tebuconazole, possibly by inhibiting normal molting or disrupting microbial homeostasis inN. lugens, and provide an important rationale for developing novel insect management strategies to delay escalating insecticide resistance. © 2023 Society of Chemical Industry.