The use of essential oils from eucalyptus leaves in arua and fort portal as pesticides for bean weevil (Acanthoscelides obtectus) and maize weevil (Sitophilus zeamais)

Abstract

Beans and maize are widely grown and stored food crops that are attacked by insect pests like the bean weevil (Acanthoscelides obtectus) and maize weevil (Sitophilus zeamais). Farmers use synthetic insecticides to control them however, these can cause many problems such as the occurrence of resistance in the insects, accumulation of residues in foods, damage to human health, and environmental contaminations. Therefore, this study aimed at evaluating the efficiency of the essential oils from Eucalyptus leaves of camuldulensis and Grandis from Arua and Fort portal. Oil was extracted by hydrodistillation using a Clevenger apparatus. The oil yielded was tested for its efficiency for insect mortality at doses of 10μl, 25μl and 50μl for the maize weevil and 5μl, 10μl, 15μl, and 20μl for the bean weevil. The LC50 was determined. Results showed that the leaves from 3-year-old Eucalyptus camuldulensis have the highest yield of oil. For the S. zeamais, mortality was observed for 72 hours with EC of three years from Arua having LC50 of 5.0 ulg-1 while for the A. obtectus, mortality was observed for 48 hours with EG from Fort portal having LC50 of 6.061 ulg-1. Comparison was made for mortality of both weevils exposed to EC of 3 years from Arua and it was observed that the LC50 to control the population of A. obtectus (7.9 ulg-1) was higher compared to the LC50 to control S. zeamais (5.0 μl g-1). The use of eucalyptus essential oil represents a promising alternative to be used under storage conditions for the integrated management of stored grains pests. However, it is recommended that further studies could be done to identify the constituents in the eucalyptus essential oil responsible for killing the insects.