Managing Sweet Potato Weevil (Cylas puncticollis) and Enhancing Tuber Yield through Legume-forage Intercropping in Southern Ethiopia

The sweet potato weevil is a critical pest, causing up to 48% yield loss in sweet potato. Understanding the interactions of soil microbes and natural enemies within diversified cropping systems is essential for effective weevil control. This study evaluated the effectiveness of legume diversification for sweet potato weevil control and yield improvement in Dilla and Hawassa, Ethiopia, during the 2017 and 2018 cropping seasons. Treatments included sweet potato intercropped with various legumes (common bean, cowpea, desmodium, lablab, and soybean) alongside sweet potato sole cropping. Results indicated that sole cropping led to significantly (p < 0.05) higher leaf infestation (68.0% - 83.3%) and weevil colonization (72.0% - 80.7%) compared to intercropping. Notably, intercropping with cowpea and lablab significantly (p < 0.05) reduced leaf infestation (33%-39%) and weevil colonization (34%-36%), while also significantly (p < 0.05) increasing marketable tuber yield (0.87-1.2 kg/plant). Lower weevil numbers per kg of infested tubers in diverse systems suggest that crop mixtures enhance habitat diversity for arthropods, boosting predator and parasite populations. Therefore, integrating within diversified cropping systems should be considered a key component of integrated sweet potato weevil management for Ethiopian farmers.