Pesticide drift and the potential toxicity to beneficial carabids.

Abstract

'Non-target' beneficial invertebrates are exposed to pesticides in arable fields and in surrounding boundary habitats, into which sprayed pesticides may drift. The aim of this work was to quantify spray drift outside sprayed areas and to investigate its potential effects on beneficial insects in a series of laboratory bioassays.
Three insecticides, deltamethrin, dimethoate and pirimicarb were evaluated against four carabids Agonum dorsale, Demetrias atricapillus, Bembidion lampros and B. obtusum. The predators were exposed to residual deposits at dilutions ranging from 0.15% to 100% of field rate. A new bioassay method was developed. The bioassays showed that dimethoate had more severe effects on the carabids than did deltamethrin or pirimicarb. Pirimicarb was the least toxic compound overall. The results are discussed in relation to the interpretation of the likely effects of drift on beneficial insects in the field.