Effects of Insecticides

Protecting crops remains a concern for all stakeholders in agriculture. The objective of this study is to analyze the phytosanitary consequences of insecticide treatment and to develop strategies to address them. The laboratory study revealed sublethal effects (cases of the LD20 of chlorpyrifos-ethyl on the olfactory detection behaviors involved in the infestation of the host by Drosophila parasitoids and aphid parasitoids). In the field, delayed effects and low infestation levels of aphid parasitoids following the application of deltamethrin and methidathion at registered doses were observed when compared to the untreated plot. The excessive use of pesticides-a common practice among Malagasy farmers-to control aphid and mite populations promotes resistance and is not technically cost-effective (as in the case of dimethoate against mites). To address these issues, we promote the use of beneficial insects through the preventive application of insecticidal plant extracts or by establishing an insect habitat consisting of flower strips to protect crops.