Changes in the distribution of lepidopteran maize stemborers in Kenya from the 1950s to 1990s

Three hundred and ninety-two maize fields in the southern arable zone of Kenya were sampled for lepidopteran cereal stemborers from 1996–2000. Chilo partellus (Swinhoe) was the most abundant stemborer, and was found at all locations with elevations below 1500 m, and at some locations between 1500 and 2300 m. The highest density of C. partellus was in the semi-arid ecological zone of eastern Kenya. Chilo orichalcociliellus (Strand) was found in the lowland southern coastal area, and a few inland sites on the border of Tanzania in southeastern Kenya. Busseola fusca Fuller was dominant in highland areas. In the Lake Victoria Basin, which has an elevation of about 1100 m, B. fusca was dominant at some sites, but overall, C. partellus was more abundant. Sesamia calamistis Hampson was present at all elevations and all locations, but typically at low densities. Eldana saccharina (Walker) was found in two-thirds of the fields sampled in the Lake Victoria Basin. These results are compared with the distributions of the various stemborers in the 1950s to 1960s, as reported in the literature.