Exposure to the Bt Cry1Ac toxin disrupts sex pheromone signaling and reduces reproductive fitness in Plutella xylostella.

BACKGROUND: Plutella xylostella presents a significant threat to Cruciferae crops worldwide, primarily due to damage from its caterpillars. This pest not only causes substantial economic losses but has also developed resistance to many conventional insecticides, prompting the need for innovative control strategies. This study investigates the effects of Bacillus thuringiensis (Bt) Cry1Ac on P. xylostella, specifically assessing the consequences of exposure to low concentrations of Cry1Ac. RESULTS: Cry1Ac exposure significantly reduced larval weights, pupation rates, and mating success, indicating adverse effects on growth and reproductive potential. Furthermore, low-concentration Cry1Ac exposure led to changes in the messenger RNA (mRNA) levels of genes associated with sex pheromone biosynthesis, as well as alterations in physiological parameters, including cyclic adenosine monophosphate (cAMP) levels, calcium ion (Ca2+) levels, and the activities of enzymes involved in sex pheromone biosynthesis, ultimately resulting in a significant decrease in sex pheromone production and mating success. Most importantly, exposure to low concentrations of Cry1Ac exhibited transgenerational effects on crucial population metrics such as survival rates and reproductive output. CONCLUSION: These findings highlight the critical need to understand the comprehensive effects of Bt proteins on pest species to develop sustainable pest management strategies that address both immediate and long-term consequences. © 2026 Society of Chemical Industry.