Facilitating the use of alternative capsid control methods towards sustainable production of organic cocoa in Ghana

Abstract

Cocoa (Theobroma cacao L.) is an important foreign exchange earner for Ghana. However, production is constrained by a high incidence of pests and diseases. Based on farmers' needs, this study focused on the control of capsids, mainly Sahlbergella singularis Haglund and Distantiella theobroma (Distant) (both Hemiptera: Miridae). Annual crop loss caused by capsids is estimated at 25 - 30%. To control capsids, formal research recommends application of synthetic insecticides four times between August and December. However, farmers hardly adopt this recommendation, which they consider unsuitable for their conditions and context. Three alternative control methods were tested with farmers: mass trapping, using sex pheromones; applying crude aqueous neem Azadirachta indica A. Juss. (Meliaceae) seed extract (ANSE) and using the predatory ant Oecophylla longinoda Latreille (Hymenoptera: Formicidae) as a biological control agent. Contrary to most previous reports, studies on temporal distribution of cocoa capsids indicated that the population peaked in March. ANSE was effective against capsids and other cocoa insect pests and did not affect the predatory ant. When O. longinoda occurred in high numbers, capsid incidence was low. Shade did not influence ant or capsid abundance significantly. ANSE caused 100% mortality of capsids in cage and 79 -88% in field experiments. The sex pheromone was as effective as ANSE or ants in suppressing capsids. All the three methods were effective and compatible; hence, they can be used in an integrated pest management strategy for cocoa, including organic production in Ghana.