Assessment of maize yield losses due to the effect of fall armyworm (Spodoptera frugiperda) infestation: the case of Trans-Nzoia County, Kenya

Invasive alien species have emerged as a production constraint, the most recent in Kenya being fall armyworm (FAW) (Spodoptera frugiperda). The pest incidence has resulted in farmer welfare damage by exacerbating the maize yield gap, a principal staple crop in Kenya. Through a field survey, 257 farmers were interviewed. Farmer perceived direct estimates and an iterative bidding procedure were used to assess maize yield losses. The majority of farmers (99%) were aware of fall armyworm and could correctly identify it. Moreover, most of the farmers (94%) ranked fall armyworm as the major pest for the 2018 cropping season, with more than 43% of the farmers describing the resulting yield loss as high. Yield loss estimates ranged between 0.18 to 2.7 tonnes per acre. Farmers adopted a combination of control strategies, to mitigate the effect of FAW. We conclude that FAW is a problematic pest in Kenya, based on the observed significant losses due to this pest. To inform policy on appropriate and prioritization of resources to manage FAW, yield loss estimates are key.