We must remember that when the U.S. Environmental Protection Agency (EPA) registered the neonicotinoid insecticides, which are clearly tied to elevated rates of decline in bee and pollinator populations, it did not have a field study to evaluate the chemicals’ overall impact on ecosystem health, let alone impacts on individual species.
Whether we are talking about the soil or aquatic food web, the agency did not do the analysis. But, it really is not difficult to see that systemic pesticides that enter the vascular system of a plant and express themselves through pollen, nectar, and guttation droplets are going to have a wide range of nontarget effects.