The pest control and pollinator protection dilemma: The case of thiamethoxam prophylactic applications in squash crops

Abstract

A major challenge in sustainable agriculture is finding solutions to manage crop-damaging pests such as herbivores while protecting beneficial organisms such as pollinators. Squash is a highly pollinator-dependent crop that is also attractive to herbivores like the striped cucumber beetle. While synthetic insecticides can provide control of insect pests, they can also affect non-target organisms such as pollinators. Thus, growers need to balance pest management with pollinator protection to ensure optimal yield. Thiamethoxam is a commonly used systemic insecticide that translocates throughout plants, leaving residues in nectar and pollen. The aim of this study was to evaluate whether there are uses of this insecticide that provides efficient pest control while minimizing pesticide pollinator exposure. Specifically, we tested how different prophylactic application methods (seed treatments, in-furrow applications, and early foliar sprays) of commercially available thiamethoxam products impact pest control, bee visitation, yield, and pesticide residues in flowers of squash crops. We found that among the different methods of thiamethoxam application, in-furrow application best prevented defoliation and resulted in the highest fruit weight and number. However, it also produced the most frequent and highest concentrations of thiamethoxam in nectar and pollen, reaching lethal levels for squash bees. Our study provides evidence that under current application methods, thiamethoxam does not provide a sustainable solution for squash growers and further research is required on more efficient pesticide delivery methods, as well as non-pesticide pest control measurements.