Unraveling acetamiprid resistance in Aphis craccivora (Hemiptera: Aphididae): resistance risk assessment, fitness costs, cross-resistance, biochemical and molecular characterization, and in silico docking study.

Aphis craccivora Koch (Hemiptera: Aphididae) is a major sucking pest of legumes. Neonicotinoid insecticides are extensively utilized for A. craccivora control. The extended use of neonicotinoids, including acetamiprid (ACP) to manage A. craccivora, has led to the development of resistance. However, the potential to delay the development of ACP resistance in A. craccivora has not yet been investigated. Our study aimed to examine the development of ACP resistance in A. craccivora over 20 generations, and the associated heritability (h2), fitness costs, biochemical mechanisms, and potential cross-resistance were evaluated. Gene expression of GST and Cyp-450 was measured under ACP exposure, and molecular docking of ACP with these proteins in the presence of diethyl maleate (DEM) and piperonyl butoxide (PBO) was analyzed. Our data showed that the ACP-resistant (ACP-R) strain of A. craccivora showed a 25.57-fold enhancement in LC₅₀ compared to the Sus-strain, with realized heritability (h²) of 0.21 and reduced fitness (0.69). The net reproduction rate (R0), mean relative growth rate (MRGR), intrinsic rate of increase (r), and finite rate of increase (λ) were markedly lower in the ACP-R strain than in the Sus-strain of A. craccivora. Upregulation of Cyp-450 (CYP18A1, CYP4CJ14) and GST (GSTS3, GSTO1) genes enhanced enzyme activity, while Car-E showed no significant correlation with ACP susceptibility. Enzyme inhibitors PBO and DEM increased ACP toxicity, and molecular docking suggested their interaction with Cyp-450 and GST proteins contributes to resistance. Our findings offer key insights into ACP resistance in A. craccivora, supporting the development of management strategies and decision-making tools.