The distribution and biology of Eldana saccharinaWalker (Lepidoptera Pyralidae) and its relationship to other stem-borers in Uganda

Abstract All available records showed that Eldana saceharina Wlk. occurs in wild plants in all suitable areas of Africa south of the Sahara. Until a few years ago, it was only of economic importance in West Africa as an occasional pest of maize and sugar-cane, but a crop-feeding form has recently appeared in East Africa. Biological studies were carried out in the field and laboratory at Kawanda, Uganda, between 1970 and 1972 using natural and artificial larval diets. The life-cycle lasted 2–3 months, depending on temperature, and the number of larval instars depended partly on the diet. The adults lived for two weeks, during which time the females each laid 400–600 eggs. The majority of eggs and small larvae were taken by ants, but sufficient larvae survived to cause considerable damage. The pupae and larger larvae lacked efficient natural enemies in East Africa, and the introduction of parasites is suggested to prevent serious crop damage. The relatively evenly spread rainfall at Kawanda allowed maize to be planted every month so that field populations of E. saccharina and the other stem-borers Chilo partellus (Swinh.), Busseola fusca (Fuller) and Sesamia calamistis Hmps. could be studied throughout the year. Collections from maize, sorghum and sugar-cane showed that, although the four species attack the same host-plants, they occupy different ecological niches.