Pesticide Usage and Implications of the Diurnal and Seasonal Dynamics of Cocoa Hemipteran Pests on their Management in South Western Cameroon

Abstract

Aims: To investigate the various synthetic chemical formulations, equipment and methods that farmers use to control cocoa insect pests and also study the abundance, diurnal and seasonal population fluctuations of these pests in South Western Cameroon. This was in a bid to factor how such information can be exploited to improve on their current control methods. Study Design: Random interview of cocoa farmers and testing of different pest management methods in a randomized block design. Place and duration of Study: Interview of cocoa farmers in Fako. Field experiment at Research farms in Ekona and Muyuka, South Western Cameroon from November 2010 to October 2011. Methodology: Structured questionnaires administered to 200 farmers to document how they managed mirids (Capsids) on their cocoa. There was also random sampling of cocoa plants in order to study the diurnal, seasonal and population dynamics of these mirids (capsids). Results: Most farmers, 120(60%) perceived capsids as the most important insect pest in cocoa farms. Among the insects caught, 420(84%) were Bathycoelia thalassina, 70(14%) Sahlbergella singularis, 10(2%) Distantiella theobroma. Higher densities of the insects were recorded during the dry season (November – March) compared to the rainy season. The diurnal population dynamics of the various insects showed that the highest numbers were observed early in the morning followed by the evening and least around noon. Most of the farmers used conventional synthetic pesticide to control the capsids and black pod diseases. Insecticides with a wide range of trade names were used against the pests which all contain synthetic pyrethroids, neonicotinoids and organophosphate as active ingredients. Cypermethrine (cypercal®) was the most frequently used while the neonicotinoid, imidaclopride were the least used. Most farmers 128(64%) used knapsacks, 20(13%) used other types of sprayers and 19(9.5%) used mist blowers. Conclusion: Integrating the judicious use of appropriately formulated insecticides and farm sanitary practices, could be exploited in the proper temporal spatial timing of insecticide application as a component of the integrated management of insect pest on cocoa to minimise residues on cocoa beans and environmental pollution.