The impact of insecticides on beneficial arthropods in cotton agro-ecosystems in South Africa.

The unique diversity of beneficial arthropods in South Africa can be regarded as an important natural resource in agro-ecosystems as it plays an important role in the natural control of insect pests. Insecticide applications reduce the ability of these beneficials to regulate cotton pests. In the absence of insecticides, average daily predation rates of 37% and 30% of bollworm eggs and larvae respectively were found in exclusion experiments. By minimizing the number of pesticide applications the combination of the direct negative effect of pesticide application on predator populations and secondary pesticide effects such as the stimulation of red spider mite populations as a result of predator suppression, can be avoided. This would open the option to fully utilize the full pest control potential of the natural enemy complex.