Distribution of sugarcane stem borers and their natural enemies in small-scale farmers' fields, adjacent margins and wetlands of Ethiopia
Novel investigations into sugarcane stem borers, their distribution and their natural enemies, were conducted in small-scale farmers' fields and indigenous host plants growing in wetlands and irrigation channels in three regions of Ethiopia. Sugarcane, in most parts of the country, was infested with two Busseola species, identified as Busseola phaia and B. fusca. The incidence of infested sugarcane stalks by these ranged between 2 and 50% in individual fields. The incidence of Chilo partellus infested sugarcane stalks was high but this species was restricted to fewer areas in the Oromia and Amhara regions. Sesamia calamistis was recorded in two of the 54 sugarcane farms visited and in the sedge, Cyperus papyrus, growing on the edge of Lake Tana. Eldana saccharina, which is the most important pest of sugarcane in other parts of Africa, was recovered only from indigenous sedges (Cyperus spp.) growing in watering channels and large water bodies. Busseola phaia has not previously been reported from Ethiopia, and ours is the first report of this species attacking sugarcane in Africa. Seven species of parasitoid wasp were recorded from all of the stem borers found: the tachinids Linnaemya sp., Schembria eldanae and Actia sp., the braconids Dolichogenidea sp. and Cotesia flavipes, an unidentified scelionid, and a solitary parasitoid of unknown taxon. Two fungal pathogens (Entomophthora sp. and Beauveria bassiana) and a bacterial disease (Bacillus thuringiensis) were also recorded.