Evaluation of the Efficacy of Three Plant Crude Extracts for the Management of Major Insect Vectors on Different Okra Varieties in Ghana

Abstract

Background: Okra production is constrained by whiteflies and flea beetles attack and the associated respective Okra yellow vein mosaic virus [OYMV] and Okra mosaic virus [OMV] diseases. The predominant control of pests and diseases using synthetic agrochemicals poses health and environmental risks. Methods: The efficacy of leaf extracts from Neem, Jathropha and Lemon grass as safer biopesticides in the control of whitefly and flea beetle populations was evaluated by insect count. The incidence and severity of OMV and OYVMV in the three okra varieties, F1 Kirene, F1 Sahari and Asuntem, were also assessed and confirmed by enzyme-linked immunosorbent assay (ELISA). Result: Neem extract significantly (p<0.05) reduced the mean incidence (21.84%) of the viral diseases than Lemon grass extract (25.28%), Jathropha extract (25.44%) and the control (28.89%). In vitro confirmation using ELISA revealed that majority (86.67%) of the treatment combinations showed single infection of OMV while 13.33% was mixed-infection of OMV and OYVMV. In terms of yield levels, Neem extract treatment (144.81 kg/ha) yielded significantly higher than Jathropha extract (139.06 kg/ha), Lemon grass extract (115.75 kg/ha) and the Control (94.02 kg/ha).