Evaluation of diploid banana genotypes for resistance to weevils (Cosmopolites sordidus) in Uganda

Banana production in Uganda, has for decades been constrained by a number of abiotic and biotic factors. Weevils are among major pests that frustrate production causing over 60% yield loses. Cultural, biological and chemical control approaches are inadequate for the management of weevils. Integrated weevil management practices should therefore incorporate banana host plant resistance. The main objective of this study was to contribute to development of weevil resistant banana varieties through identifying sources of resistance and an effective weevil screening method. The specific objectives were to: 1) evaluate outsourced diploid banana germplasm for response to weevil in Uganda, 2) assess the field performance of the outsourced diploid banana germplasm for agronomic traits and pollen quantity, and 3) determine the effectiveness of the pot bioassay in screening bananas for response to weevil damage. Objectives were achieved by: 1) assessing percentage corm damage of banana germplasm infested with weevils both in the field and pot experiments, 2) field assessment of 12 banana genotypes for both agronomic traits and pollen quantity, and 3) performing correlation analysis of the field and pot bioassay weevil damage data. The study results showed that diploids ‘Saing hil’, ‘Pisang gigi buaya’, ‘Pisang rotan’, ‘Pisang tunjuk’, ‘Morong princessa’, ‘Morong datu’ and ‘Gabah gabah’ were resistant to weevils indicated by low peripheral and cross section corm damage that was non-significant from that of a resistant control ‘Calcutta 4’. Diploids ‘Saing hil’ and ‘SH-3142’ exhibited high pollen quantity, close to that of ‘Calcutta 4’, the highest male fertile wild diploid (AA). Pot and field experiment results showed low positive non-significant correlation for all weevil damage attributes, indicating that the pot assay gives insufficient results to draw conclusions about the resistance of bananas to weevils. Resistant diploids should be incorporated into breeding program after comprehensive study of their pollen quantity and quality attributes.