Comparative toxicity of pyrethroid insecticides to terrestrial and aquatic insects

The acute toxicities of three pyrethroid insecticides (permethrin, cypermethrin, and bi‐fenthrin) and one organophosphate insecticide (chlorpyrifos) were compared by topical application and static exposure to a variety of terrestrial and aquatic insects. Mayflies and damselflies were the most susceptible taxa tested by both exposure methods. The aquatic insects were generally more susceptible than the terrestrial insects when compared on a dose per body weight basis, although the differences were smaller than expected, given the extremely low concentrations that produce toxic effects by static exposure.