Assessment of Insect Spectrum, and Insect-Induced Damage at Different Growth Stages of Cucumber (Cucumis sativus L.) In A Rainforest Transition Zone Of Nigeria

Abstract

In Nigeria, published information on the range and relative importance of different pests on cucumber is scanty. Studies were therefore carried out in a survey to determine the insects associated with cucumber, and on-field to quantify insectinduced damage at different crop growth stages. Surveys were carried out in five cucumber fields each at Ibadan, Oyo State, and Abeokuta, Ogun State, Nigeria. In the field experiment, cucumber plants were protected at different stages: pre- flowering, flowering, post-flowering/fruiting, or all growth stages with lambdacyhalothrin sprayed weekly at 25g a.i/ha. The control plots were without insecticide protection. Insects recorded from the surveys included: Zonocerus variegatus, Podagrica uniforma, Aphis gossypii, Myzus persicae, Bemisia tabaci, Thrips tabaci, Epilachna chrysomelina, and fruit flies Bactrocera invadens and Dacus ciliatus. Other insects found were Cheilomenes lunata and Chelisoches flavipennis, which are natural enemies of whiteflies and aphids, respectively, and the honey bees, Apis meliferae, which is a pollinator. Significantly higher number and heavier fruits, which were not statistically different from those recorded in full protection plots, were produced when cucumber was protected at post-flowering stage. Fruit fly damage in unprotected [lots was 60% and 55%, while that of the Epilachna beetle was 55% and 46% in 2004 and 2009, respectively. Yield was significantly higher by 50% in plots sprayed at post-flowering stage over the control. Epilachna beetle and the fruit flies attacking at the post-flowering/fruiting stage are therefore, important in cucumber production, and the fruiting stage is the most critical where insect pest control measures must be applied.