Abundance and Diversity of Insects Associated with Citrus Orchards in Two Different Agroecological Zones of Ghana

Abstract

We investigated the abundance and diversity of entomofauna associated with citrus orchards in two different agroecological zones of Ghana. Malaise traps, flight interception traps, pitfall traps, chemical ʽʽknock down’’ and visual observation were used for data collection. We recorded a total of 20, 285 individual insects belonging to 387 species from 107 families and 13 orders. Although, several species of insects were common to both agroecological zones, some were more specific to an orchard of a particular zone. Diversity indices such as Shannon-Wiener index, Pielou’s evenness and Margalef index were higher in the Coastal Savannah zone than the Semi-Deciduous Rainforest zone during both the wet and the dry seasons. Oecophylla longinoda Latreille was the most dominant insect species in each agroecological zone, however, they were more abundant in the semi-deciduous rainforest than the Coastal Savannah zone. Our study shows that only 9% of all the 387 insects collected were pests of citrus. This indicates that citrus orchards are potential habitats for insect biodiversity conservation. We therefore recommend that management tactics which have less or no negative effects on natural enemies, pollinators among others but can effectively suppress insect pest populations (such as the use of biological control agents, restriction of herbicides and pesticides) should be adopted. Our study has also provided the first comprehensive inventory of insect species associated with citrus agroecosystems serving as a baseline data for further studies to encourage adoption of economically sound integrated pest management approach for citrus production in Ghana.