THE IMPACT OF INSECTICIDES ON BENEFICIAL ARTHROPODS IN COTTON AGROECOSYSTEMS IN SOUTH-AFRICA

The unique diversity of beneficial arthropods in South Africa can be r egarded as an important natural resource in agro-ecosystems as it play s an important role in the natural control of insect pests. Insecticid e applications reduce the ability of these beneficials to regulate cot ton pests. In the absence of insecticides, average daily predation rat es of 37% and 30% of bollworm eggs and larvae respectively were found in exclusion experiments. By minimizing the number of pesticide applic ations the combination of the direct negative effect of pesticide appl ication on predator populations and secondary pesticide effects such a s the stimulation of red spider mite populations as a result of predat or suppression, can be avoided. This would open the option to fully ut ilize the full pest control potential of the natural enemy complex.