Multiple target-site mutations occurring in lepidopterans confer resistance to diamide insecticides

Area of Science:

• Entomology
• Molecular Biology
• Pesticide Resistance

Background:

• Diamide insecticides are crucial for controlling lepidopteran pests.
• Field-evolved resistance to diamides has been observed in various insect species.
• Target-site mutations in the ryanodine receptor (RyR) gene are a known mechanism of diamide resistance.

Purpose of the Study:

• To assess the diamide resistance status of Chilo suppressalis populations in China.
• To identify and characterize target-site mutations in the RyR gene of resistant C. suppressalis.
• To investigate the functional impact of identified RyR mutations on diamide insecticide efficacy.

Main Methods:

• Field surveys and bioassays to determine resistance levels in C. suppressalis populations.
• Sequencing of relevant domains of the C. suppressalis RyR gene.
• Toxicity bioassays using genome-modified Drosophila melanogaster lines expressing specific RyR mutations.

Main Results:

• Multiple RyR target-site mutations (I4758M, Y4667D/C, G4915E, Y4891F) were identified in resistant C. suppressalis.
• The Y4667D mutation (alone or with I4758M) conferred high resistance ratios to chlorantraniliprole, cyantraniliprole, and tetrachlorantraniliprole.
• Simultaneous M4758I and G4915E mutations showed high resistance to chlorantraniliprole and cyantraniliprole, with lower resistance to flubendiamide and tetrachlorantraniliprole.

Conclusions:

• Multiple point mutations in the RyR gene are responsible for diamide resistance in Chilo suppressalis.
• These findings enhance understanding of insect diamide resistance mechanisms.
• The study highlights the significant role of RyR target-site mutations in conferring insecticide resistance in insects.