Role of vectors and their host plants in the epidemiology of maize lethal necrosis in eastern Africa

The prevalence and severity of a new maize disease complex known as Maize Lethal Necrosis (MLN) caused by viruses such as Maize chlorotic mottle virus (MCMV), and Sugarcane mosaic virus (SCMV) has resulted in 100% yield loss in severely affected areas in Kenya. The disease has spread rapidly to other eastern Africa countries like Uganda, Tanzania, Rwanda and DRC Congo. Despite this rapid spread, role of potential vectors in the disease epidemiology and sustainable vector management strategies are poorly understood in eastern Africa. Hence we focused to identify potential vectors and estimate their competencies to transmit MLN-causing viruses, and to determine their host plants and natural enemies. Field surveys to determine the seasonality and diversity of potential vectors of MLN-casing viruses were carried out in MLN hotspots in Kenya. The presence of MLN viruses in wild grasses and other cereal crops were detected by DAS-ELISA and RT-PCR. Potential vectors in the MLN positive hosts were recorded. The transmission competencies of such potential vectors were determined under laboratory and semi-field experiments at icipe. The role of some identified vectors such as corn leaf aphid (Rhopalosiphum maidis), corn thrips (Frankliniella williamsi), epilachnid beetle (Epilachna similis) and other potential vectors, their host plants in the spread of MLN will be discussed.