Molecular Detection and Epidemiology of Tomato Yellow Leaf Curl Virus in South West Nigeria

Tomato Yellow Leaf Curl Virus (TYLCV), transmitted by the whitefly Bemisia tabaci, is one of the most economically destructive viral diseases of tomato production in sub-Saharan Africa. Although the disease has been reported in several Nigerian states, systematic molecular epidemiological data on its distribution, strains, and incidence levels across South West Nigeria remain limited. This study conducts a molecular detection and epidemiological analysis of TYLCV in tomato-producing communities across Oyo, Osun, and Ogun states using PCR-based detection, DNA sequencing, and spatial incidence mapping. Symptomatic tomato leaf samples were collected from 60 farms during the 2023 main and off-season cropping periods. Viral DNA was extracted, amplified using TYLCV-specific primers, and sequenced. Whitefly population dynamics were monitored alongside viral incidence. Results confirm the presence of TYLCV in 78 percent of sampled farms, with the Israeli-B strain dominant across all three states. Whitefly population peaks were strongly correlated with viral incidence peaks with a three-week lag. The study recommends mandatory use of TYLCV-resistant tomato varieties, insecticidal whitefly management starting at transplanting, and the development of a real-time disease monitoring system for the South West tomato corridor. Keywords: TYLCV, tomato, molecular detection, whitefly, South West Nigeria