Odonate Larvae as an Indicator of Pesticide Contamination

Abstract

The abundance of odonate larvae was surveyed in a river system at two upstream stations surrounded by rice fields lacking aerial spraying of pesticides, two midstream stations surrounded by rice fields with and without aerial spraying, and four downstream stations surrounded by sprayed fields. Species diversity and numbers of individuals were much lower at the downstream stations. Pesticide contamination from ground spraying occurred at one upstream station as well as one midstream and all downstream stations. Damage to the odonate larvae was not clearly evident except at one downstream station. Damage by the aerially sprayed insecticides seemed appreciable at the downstream stations. The distribution of odonate larvae in a river may be restricted by pesticide contamination and thus can indicate pesticide contamination.