Insects feeding on Sesbania species in natural stands and agroforestry systems in southern Malawi

Pest and disease interactions in agroforestry systems is a little studied a rea. Surveys were conducted in the Mangochi and Zomba districts of southern Malawi between December 1997 and February 1998 to identify insects feeding on Sesbania species in natural stands and in agroforestry systems at the r esearch station and on farms, and the host range of the insects. Out of a t otal of 30 insect species recorded in natural stands, Brachyplatys testudon igro, Mesoplatys ochroptera, Exosoma sp. and Ootheca sp. were the most comm only found insects feeding on S. sesban. Afrius figuratus, Glypsus conspicu us, Macrorhaphis acuta, Mecosoma mensor, Rhinocoris segmentarius and Cyaneo dinodes faciger were recorded for the first time as natural enemies of Meso platys ochroptera in Malawi. The defoliating beetles, M. ochroptera, Exosom a sp. and Ootheca sp., were the most frequently found insects infesting S. sesban on farms. M. ochroptera attacked only Sesbania species, and usually higher populations of this beetle were recorded on annual Sesbania species (S. tetraptera, S. bispinosa, S. leptocarpa and S. sericea) than on perenni al types. Although the sap-sucking bug, B. testudonigro, was relatively les s common on sesbania on farms, it has been found to infest a number of othe r legumes of the genera Aeschynomene, Crotalaria, Desmodium, Indigofera, Mu cuna, Phaseolus, Tephrosia and Vigna. Given the wide variety of plant speci es it attacks, B. testudonigro may become a potential pest of many agrofore stry tree species. The insects Anoplocnemis curvipes, Aphis fabae, Hilda pa truelis, Megaleurothrips sjostedti, Mylabris dicincta, Nezara viridula and Ootheca sp. also have the potential to become pests of agroforestry systems , as they can damage many agroforestry trees, including Sesbania, and crops . There is a need to study the biology and ecology of potential insect pest s of S. sesban to plan for their integrated management in agroforestry.