Crop injury and yield losses in maize by the African maize stem borer, Busseola fusca (fuller) (lepidoptera: Noctuidae) in Southern Ethiopia

Abstract

African maize stem borer, Busseola fusca is an important pest of maize in sub-Saharan Africa. This study investigated the relationship between B. fusca population density and yield losses in maize. Twenty four maize farms were visited in 12 localities of southern Ethiopia at three growth stages of maize during 2015 and 2016. Data were collected on percent of infestation, number of larvae and pupae, crop injury variables and grain yield per plant from insecticide protected and not-protected plots. Busseola fusca was present in damaging levels in all the study areas during both years. Infestation, population density and crop injury variables significantly varied between years, growth stage of maize and locations. As altitude increase, levels of infestation, population density, crop injury and grain yield losses increased. Population density of B. fusca was higher at mid-whorl than silking and maturity stages of maize. A single stem borer, B. fusca per plant reduced grain yield by 9.2 g/plant. Similarly, 1 cm tunnel length and one hole per plant reduced grain yield by 1.3 and 4.8 g/plant, respectively. Crop injury and maize grain yield losses significantly lower in protected plot than unprotected. To reduce crop injury and yield losses in maize due to stem borer, farmers especially in higher elevations need to monitor their crop and use effective intervention methods.