Control of cocoa mirids using aqueous extracts of Thevetia peruviana and Azadirachta indica

Mirids, Sahlbergella singularis, are the most harmful cacao pest in Africa. Chemical management, although controversial, is currently the only effective option for controlling these pests. Based on in vitro and field experiments, this study evaluated and compared the effectiveness of aqueous extracts obtained from the seeds of Thevetia peruviana (TP) and Azadirachta indica (AI) in controlling cocoa mirids, S. singularis. Thevetia peruviana extracts proved to be more effective than A. indica extracts and were as effective as Actara 25 WG, the benchmark insecticide, in reducing mirids in the field. All the aqueous extracts tested in vitro displayed insecticidal activities within maximum eight days and some repellent effects at both 10 and 25% w/v. Treatment of mirid food with the extracts also led to high mortality rates and to significant avoidance of pods treated with the TP25, TP10 and AI25%. The use of plant aqueous extracts to control mirids in the field thus offers promising prospects for the control of this pest, given the availability of the plants, their simple preparation, their effectiveness and their eco-friendly features