Efficacy of botanical insecticides on insect infestation and fruit yield of eggplants (Solanum melongena L.) in Ogbomoso, Oyo State, Nigeria

Abstract

Field trials were conducted during 2016 and 2017 raining seasons at the Teaching and Research Farm, Ladoke Akintola University of Technology, Ogbomoso, to determine the effects of leaf extracts of Pawpaw, Tobacco and Cashew leaves on insect pests of three selected eggplant varieties (Solanum depressum; Solanum escullantum and Solanum serpentium). Synthetic insecticide (Lambda-cyhalothrin) and untreated plants were included in the experiment for comparison and each treatment was replicated three times at 20% v/v. The experiments were laid out in Randomized Complete Block Design. Data were collected on insect pests variations and fruit yield. Four major insect pests of eggplant – Zonocerus variegatus, Spodoptera litoralis, Leucinodes ornabalis and Epilachna species were observed. Among the tested varieties, S. depressum had the least significant (P< 0.05) infestation (6 - 13%). All the tested leaf plant extracts were effective in the control of the observed insect pests when compared with the level of insect pest attack on untreated plants. However, cashew extract had highest insecticidal efficacy (55%) compared with other tested plant extracts while insecticidal potential of pawpaw extract was comparable to tobacco extracts. Meanwhile, none of the tested plant leaf extracts was as effective as Lambda-cyhalothrin in the control of the observed insect pests. Among the tested varieties, Solanum depressum had highest fruit yield (3.45 - 3.88 t/ha) and least fruit damage.