Repellent effect of plant terpenes compound from Eucalyptus camaldulensis leaves extract for the regulation of cowpea flower damage caused by Megalurothrips sjostedti (Trybom 1908) (Thysanoptera: Thripidae)

Abstract

Cowpea flower thrip causes considerable damage to the cowpea plant, particularly at the flowering stage of the plant. This study employed Eucalyptus camaldulensis leaf extract as a regulatory mechanism to lessen the impact of Megalurothrip sjostedi. The Gas chromatography mass spectrometry (GC-MS) method was used to examine the composition of the essential oil. Three cowpea varieties;ITOK7-318-33, ITOK7-292-10, and VITA-7 were evaluated. The experiment was conducted during the 2017 cropping season and laid out in a randomized complete block design with three replications. Four treatments 500, 250, 125, and 0 μg/mL of a terpene compound from Eucalyptus camaldulensis leaf extract were selected. Flower damage was recorded as browning or drying, and flower bud abscission was estimated for each treatment. Results obtained indicate that Plants treated with 500μg/mL recorded no browning or drying of stipules, leaf, or flower buds and no bud abscission, whereas untreated 0μg/mL plants recorded distinct browning or drying of stipules, leaf, or flower buds and some bud abscission after 24 hours of treatment. The results obtained in this study suggest that Eucalyptus camaldulensis leaf extracts can serve as an alternative product for the control of cowpea flower thrip (M. sjostedti). Additional research ought to be done to determine whether of the separated component from the same plantand the crude additiona is more beneficial.