DISTRIBUTION OF SWEETPOTATO VIRUSES AND VECTORS UNDER CURRENT AND FUTURE CLIMATE CHANGE SCENARIOS IN KENYA

Sustainable agricultural productivity and food security are critical concerns in the face of climate change. Sweetpotato (Ipomoea batatas) is among climate smart crops that can strengthen farming resilience and enhance food and nutrition security in Sub-Saharan Africa. However, farmers have not been able to achieve optimum productivity partly due to diseases caused by sweetpotato viruses. This study sought to identify experiences and practices of sweetpotato growers; assess prevalence of sweetpotato chlorotic stunt virus (SPCSV), sweetpotato feathery mottle virus (SPFMV) and their vectors; and model their future distribution under climate change scenarios. The association of viruses with sweetpotato in the surveyed area was confirmed by Reverse-Transcriptase polymerase chain reaction (RT-PCR) using the primers designed by International Potato Center (CIP), Lima-Peru. Occurrence data (294) of sweetpotato viruses and (65) vectors (whitefly and aphid) collected from field surveys and the Kenya Agricultural and Livestock Research Organization (KALRO) database were used as dependent variables. MaxEnt model was used to model the spread of sweetpotato vectors and viruses, with bioclimatic data retrieved from AfriClim and soil data from ISRIC database as independent variables. Occurrence of virus disease and vectors was 51 and 31.6% respectively and the models’ most significant variables were moisture (moisture index moist quarter) and temperature (number of dry months and length of longest dry season). The results showed that the geographic extent of areas at risk of sweetpotato virus disease will increase for Kenya under future climate change scenarios from a current 36,736.09 km2 to about 63,179.76 km2 but it will decrease for Homabay County from a current 2,804.92 km2 to 2,625.05 km2by 2085. Increase in temperature and moisture variables will enhance niche suitability for sweetpotato viruses and vectors. Therefore, the situation calls for climate smart practices such as better crop timing, better cultivar choice and management, integrated pest management and sustainable cropping systems to enhance sustainable production of sweetpotato crop.