Acetamiprid Resistance in Cowpea Aphid Carries Measurable Fitness Costs, Study Finds

The cowpea aphid, Aphis craccivora, is a major sucking pest of legume crops, and neonicotinoid insecticides such as acetamiprid are widely used against it. According to a new study published in Ecotoxicology, sustained exposure to acetamiprid has now been linked to the development of resistance in this aphid, and the researchers set out to characterize how that resistance develops and what it costs the insect.

The team selected an acetamiprid-resistant strain over 20 generations in the laboratory and compared it with a susceptible strain. After the selection period, the resistant strain showed a 25.57-fold increase in the LC50, the concentration killing half of the tested aphids, relative to the susceptible strain. The realized heritability of resistance was estimated at 0.21, indicating that the trait can be passed to subsequent generations at a moderate rate.

Resistance did not come free. The resistant strain showed reduced overall fitness, measured at 0.69, and several population-growth parameters were markedly lower than in the susceptible strain. These included the net reproduction rate, the mean relative growth rate, the intrinsic rate of increase, and the finite rate of increase, all of which were reduced in the acetamiprid-resistant aphids.

At the biochemical level, the researchers found upregulation of two major detoxification enzyme systems. Genes encoding cytochrome P450 monooxygenases, specifically CYP18A1 and CYP4CJ14, and glutathione S-transferases, specifically GSTS3 and GSTO1, were upregulated under acetamiprid exposure, and this was accompanied by enhanced enzyme activity. In contrast, carboxylesterase activity showed no significant correlation with acetamiprid susceptibility, suggesting it plays little role in the observed resistance.

To probe the contribution of these enzymes further, the researchers used two known enzyme inhibitors. This synergistic effect supports the idea that these enzyme families contribute to the resistance phenotype.

The study also included an in silico component. Molecular docking analyses modeled how acetamiprid interacts with the cytochrome P450 and glutathione S-transferase proteins in the presence of piperonyl butoxide and diethyl maleate. According to the authors, the docking results suggest that the interactions of these inhibitors with the two enzyme types contribute to the resistance mechanism observed experimentally.

The work was conducted by Ahmed A. A. Aioub, Sarah I. Z. Abdel-Wahab, and colleagues, and published in the journal Ecotoxicology on 22 October 2026 as Volume 35, article number 184. The study design covered resistance risk assessment, fitness costs, cross-resistance evaluation, biochemical and molecular characterization, and computational docking, all centered on a single aphid species under laboratory conditions.

The authors state that their findings offer key insights into acetamiprid resistance in Aphis craccivora and could support the development of resistance-management strategies and decision-making tools. Because the results come from laboratory selection over 20 generations of one pest species, translating them to field settings will require further work, but the identification of specific detoxification genes and the fitness costs associated with resistance provide concrete targets for monitoring and managing acetamiprid resistance in legume-growing systems.

Subject of Research: Development of acetamiprid resistance in the cowpea aphid Aphis craccivora, including fitness costs, heritability, and biochemical mechanisms

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

Article References: Aioub, A. A. A., Hashem, A. S., Ahmed, H. H. R., Alkeridis, L. A., Al-Shahari, E. A., Shukry, M., Hamada, H. M. A., Sayed, S., El-Harairy, A., & Abdel-Wahab, S. I. Z. (2026). Unraveling acetamiprid resistance in Aphis craccivora (Hemiptera: Aphididae): resistance risk assessment, fitness costs, cross-resistance, biochemical and molecular characterization, and in silico docking study. Ecotoxicology, 35(9), Article 184. https://doi.org/10.1007/s10646-026-03163-z

Image Credits: AI Generated

DOI: 10.1007/s10646-026-03163-z

Keywords: acetamiprid, Aphis craccivora, neonicotinoid resistance, cowpea aphid, fitness costs, heritability, cytochrome P450, glutathione S-transferase, piperonyl butoxide, diethyl maleate, molecular docking, insecticide resistance management