Evidence of active oviposition avoidance to systemically applied imidacloprid in the Colorado Potato Beetle (Leptinotarsa decemlineata)

Agricultural pests can develop behavioral resistance to insecticides via choosing to feed or oviposit on non-toxic hosts. As young larvae have relatively low mobility, oviposition preferences from female adults may play a critical role in shaping the evolutionary trajectory of pest populations. While oviposition avoidance of toxic hosts was found in different agriculture pests, it remains unclear whether such preferences can be learned from female adults. To address this question, we investigated feeding and oviposition preferences to imidacloprid in the Colorado Potato Beetle (CPB, Leptinotarsa decemlineata), a major potato pest. We first identified two CPB strains that have different levels of resistance to imidacloprid. Then, we performed choice assays in the two strains and found that both strains did not have an innate feeding avoidance to systemically applied imidacloprid at both larval and adult stages. Further oviposition choice assays showed that the susceptible strain preferred to lay eggs on insecticide-free plants while the resistant strain did not. Analysing moving patterns of the two strains suggested that the oviposition preference is likely due to active learning by the female adults. Together, these results indicate that CPB can have active oviposition avoidance, which might have contributed to the rapid global invasion of this agricultural pest.