Insect Diversity of Cocoa Under Different Management Systems in Central and Eastern Regions of Ghana.

ABSTRACT

Cocoa is Ghana's dominant cash crop and the major economic activity for over 800,000 households, with around 6.3 million Ghanaians but insect pest is causing devastating effect on yield. This study sought to obtain information about insect diversity, to generate species list of entomofauna in cocoa farms, to compare the diversity and abundance of the insect and to determine the monthly variation of insect species under differently managed systems in Semi-Deciduous Rain Forest (Suhum) and the Coastal Savanna (Dunkwa) agro-ecological zones of Ghana. The two farming systems are organic and inorganic farms at Suhum and Dunkwa respectively. Each system was replicated three times each of an acre size and one hundred cocoa trees selected. Methods such as Hand height visual count method, Canopy method, and Knockdown method were used and other sampling methods such as pitfall, coloured bowl trap and fruit baited trap were also employed during the data collection. A total of 13,742 individual insects belonging to 138 species from 63 families and 12 orders were recorded and identified. Several species of insects were common to both sites but notwithstanding, other were specific to cocoa farm of a peculiar agro-ecological zone. Relatively more individual insect species were associated with the cocoa farms in the SemiDeciduous Rain Forest than Coastal Savanna but in terms of numbers Coastal Savanna recorded highest using the Shannon- Weiner, Pielous evenness, Simpson dominance and Equitability diversity indices. Generally, Oecophylla longinoda was the most dominant species in both sites. Aside that, Planococoides njalensis was the dominant species in Suhum whilst Sahlbergella singularis was also dominated in Dunkwa. There was significant correlation between climatic factors and insect abundance in both zones. Insect interaction led to damage of fruits, leaves, and stems and also exposed fruits and tree trunk to pathogenic infection such as Phytopthora. However, predators and other natural enemies were observed protecting some of the cocoa trees