Synergistic effects of selected botanicals as insecticide against insect pests of cucumber (<i>Cucumis sativus L.</i>)

Abstract

Continuous use of synthetic insecticides has been reported to pose dangers to environmental health and it has become imperative to provide alternatives that will be friendly to the environment. Studies have shown that some botanicals have low efficacy which can be
increased by the combination of other plant species for synergistic effects.The synergistic effects of the combination of five insecticidal plant extracts (Lantana camara Linnaeus, Zingiber officinale Rosh, TithoniadiversifoliaHemsl, Azadirachtaindica A.Jussand Piper guineenseSchum and Thonn) combined in ratio 1:1 with karate and untreated (control) against insect pests of cucumber were  evaluated at the Teaching and Research Farm, Ladoke Akintola University of Technology, Ogbomoso, Oyo State, Nigeria between 2015 and 2016. Treatments were laid out in Randomized Complete Block Design (RCBD) replicated thrice. Data collection commenced at 2 weeks after planting (WAP) and was taken on weekly basis for six weeks. Severity of insect damage carried out on fruits, and its effect on total yield were assessed. Major insect pests observed were PhyllotretacruciferaeFabricius,Diabrotical undecimpunctataHowardi Barber, Epilach navigintiopunctata Fabricius and Monoleptaspp Coquillett. The mixture of Z. officinale + A. indica had least mean number of 1.55 insects, Piper guineense + T. diversifolia had 1.64 insects with control having 2.97 against Monoleptaspp. Similar result was obtained from other insect pests. Higher cucumber yield was observed on all treated plots with highest on Z. officinale + A. indica 0.63 t/ha. It can be concluded from the results presented that mixture of the plant extracts of any of the five plants could be used to control insect pests of cucumber.

Keywords: Insect pests, Botanical insecticides, Karate, efficacy, Plant extracts.