The Effect of Temephos and Chlorpyrifos on the Aquatic Insect Community of a New Jersey Salt Marsh 1

Abstract

The effects of 4 biweekly applications of recommended dosages of the mosquito larvicides temephos and chlorpyrifos on the community structure and seasonal succession of aquatic insects inhabiting salt marsh potholes were examined. Using an open-ended cylinder, benthic, neustonic and nectonic organisms were sampled at weekly intervals in treated and untreated potholes from May 29 through Aug. 15, 1974. Twenty species of aquatic insects were recovered, including both larval and adult life stages. One corixid, Trichocorixa verticalis (Fieber), dominated the pothole community. Effects of the larvicides on insect community structure were tested by monitoring species richness, species diversity, and densities of dominant, subdominant and predatory insects before and after pesticide applications. The results of this study confirmed that temephos and chlorpyrifos were selective mosquito larvicides, controlling bloodsucking Nematocera without significantly changing the species richness and diversity of the nontarget salt marsh aquatic insect community or altering the densities of the dominant insects.