Understanding Mechanisms of Pesticide Resistance to Thiamethoxam in the Cotton Aphid

A. gossypii on cotton leaf. Image credit: Clemson University - USDA Cooperative Extension Slide Series, , United States [CC BY 3.0 (https://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
A. gossypii on cotton leaf. Image credit: Clemson University – USDA Cooperative Extension Slide Series, , United States [CC BY 3.0 (https://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

The extensive and repetitive use of neonicotinoids has led to the development of resistance in several insect species including, the cotton aphid, A. gossypii. A. gossypii is a widely distributed pest that affects watermelons, cucumbers, pumpkin, cotton, and citrus crops, among others, making it one of the most economically important agricultural pests known. Thiamethoxam is a neonicotinoid insecticide that irreversibly binds to the nicotinic acetylcholine receptors (nAChRs) of cells in the nervous system and interferes with the transmission of nerve impulses in insects (1).

To further understand the mechanisms of resistence to thiamethoxam and other neonicotinoids, Wu et al. recently investigated (2) expression changes in the transcripts of P450 in thiamethoxam-susceptible and thiamethoxam-resistant cotton aphid strains. Nine P450 genes were significantly overexpressed in the resistant strain (especially CYP6CY14). The involvement of overexpressed P450s was examined through RNA interference (RNAi) introduced via artificial diet and dsRNA feeding.

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