Effects of cotton inter-cropping systems on establishment and biological control efficacy of the Lepisiota spp predator ant on major insect pests

Abstract

Studies were conducted along Otwal-Amuria transect and at Serere Agricultural and Animal Production Research Institute (SAARI) to establish choice and preference, host association and ecological conditions necessary for establishment and biological insect pest management by the predatory ants Lepisiota spp on major cotton insect pests. Survey results showed that this particular species of ants was only present in Otwal subcounty in Apac district, Aromo and Ogur sub-counties in Lira district numbering 128.3, 70.9 and 68.8 ants per trap catch respectively. The survey showed that the ants prefer particular environmental conditions for their survival and insect pest management effectiveness. This restricted occurrence could also be a result of restrictions on the use of agricultural chemicals like insecticides in the study areas through Lango Organic Promotion. Inter-cropping results showed that ant response to artificial food bait was highest in plots with sole cotton, sorghum, hibiscus and maize inter-crops. Ant trap catches were negatively correlated with aphid infestation level. This indicated that for good early establishment, rapid population build-up and

effectiveness a food bait for aphids like legumes should be inter-cropped with cotton. No-choice tests showed that these ants feed on all stages of bollworms, Lygus and Stainer bugs with a preference to younger stages. Choice tests showed that the ants preferred bollworms. Yield results showed that although pest management by these predators were good on legume inter-crops, the low yields realized from cowpea, maize and sorghum inter-crops were mostly due to their suppressive effects on cotton.