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Beta-cypermethrin is a commonly used insecticide for controlling major agricultural pests as Helicoverpa armigera in crop fields. This study investigated the sublethal effect of beta-cypermethrin on the mating physiology of H. armigera. The results demonstrated that the sublethal exposure to beta-cypermethrin significantly decreased sex pheromone production, hindered female ability to attract males and reduced the proportion of successful matings. Further investigations revealed that trehalose content in the sex pheromone glands (PGs) significantly decreased following sublethal beta-cypermethrin treatment, leading to a subsequent decrease of acetyl-CoA content within the PGs. Furthermore, such exposure caused a significant decrease in mRNA expression levels of the trehalose transporter, calcineurin (CaN), acetyl CoA carboxylase (ACC), protein kinase A (PKA), pheromone biosynthesis-activating neuropeptide receptor (PBANR), Δ11-desaturase (DES) and fatty acid reductase 2 (FAR2), as well as a decrease in the enzyme activities of membranebound trehalase, ACC, CaN and PKA. Sublethal exposure lowered the expression levels of pheromone binding protein 1, pheromone binding protein 2 and odorant receptor 13 in males, suggesting decreased male recognition capabilities. Altogether, sublethal exposure to beta-cypermethrin resulted in a decrease in the precursor material (trehalose, acetyl-CoA) and enzyme activities involved in sex pheromone biosynthesis, This, in turn, led to reduced pheromone production and female attractiveness, as well as diminished male detection abilities, ultimately resulted in a lowered likelihood of successful mating. This study enhances knowledge on how sublethal pesticide exposure affects pest biology and their mechanisms of action, providing a basis for including such impact in pest management strategies. [ABSTRACT FROM AUTHOR]

BACKGROUND: Extensive planting of transgenetic Bacillus thuringiensis crops has driven the evolution of pest resistance to Cry1Ac. Adjustment of cropping structures has promoted further outbreak of Helicoverpa armigera in China. To control this pest, a combination of pyramiding RNA interference (RNAi) and Cry2Ab is considered a promising strategy for countering cross-resistance and enhancing the toxicity of Cry2Ab to cotton bollworm. We explored the possibility of using calcineurin (CAN) as a target RNAi gene, because it is involved in cotton bollworm responses to the toxicity of Cry2Ab. RESULTS: Cry2Ab treatment led to a significant increase in HaCAN mRNA level and HaCAN activity. Suppression of HaCAN activity due to RNAi-mediated knockdown of HaCAN increased the susceptibility of midgut cells to Cry2Ab. The increase in HaCAN activity shown by heterologous expression of HaCAN reduced the cytotoxicity of Cry2Ab to Sf9 cells. Moreover, ingestion of HaCAN-specific inhibitor FK506 increased the toxicity of Cry2Ab in larvae. Interestingly, HaCAN does not function as a Cry2Ab direct binding protein that participates in Cry2Ab toxicity. CONCLUSIONS: The results in this study provide evidence that suppression of HaCAN not only affected the development of the cotton bollworm, but also enhanced the toxicity of Cry2Ab to the pest. HaCAN is therefore an important candidate gene in cotton bollworm that can be targeted for pest control when the pest infests RNAi+Cry2Ab crops. Meanwhile, the mechanism of action of HaCAN in Cry2Ab toxicity suggested that protein dephosphorylation was involved. [ABSTRACT FROM AUTHOR]