Botanicals for the management of insect pests in organic vegetable production

Abstract

This study was conducted to evaluate the efficacies of some botanical products on insect populations associated with two vegetables; Eggplant and Okra. Two field experiments were conducted on-station at the CSIR-Crops Research Institute, Kwadaso, Kumasi, and on-farm at Eatwell farm at Agona-Mampong all in the Ashanti region of Ghana from December 2009 to March 2010 and September to December 2010, respectively. Seven botanical treatments were applied viz; Ecogold (10 ml/l of water); Alata soap (5 g/l of water); Garlic (30 g/litre of water); Neem oil (3 ml/l of water); Papaya leaves (92 g/l of water); Wood ash (10 g/plant stand) and control (no botanical). The experimental set up was a Randomized Complete Block design (RCBD) with three replications. Parameters studied included insect pest numbers and their natural enemies, number of days to 50% flowering, plants height at flowering (cm), number of fruits per plant, fruit damage, and mean weight of fruits (g). Major insect pest recorded on the two vegetables included aphids (Aphis gossypii), flea beetles (Podagrica spp), whiteflies (Bemisia tabaci), fruit borers (Earias sp), cotton strainers (Dysdercus superstitiosus (F.)), variegated grasshoppers (Zonocerus variegatus L.), Urentius hysterricellus (Richter) and shoot and fruit borers (Leucinodes orbonalis Gn). The natural enemies of pests of the two vegetables identified were the ladybird beetles, (Cheilomenes sp) and predatory spiders (Araneae). There were significant percentage reductions in pests for all the botanicals applied (P< 0.05) on both the eggplant and okra plants compared to the control. Generally, plants to which the botanicals were applied produced the highest mean weight of fruits, translating into mean percentage increases in fruit weight ranging between 21 and 59% on both the eggplant and okra plants compared to the control in both growing periods. It is concluded that botanicals such as Ecogold, Alata soap, exotic garlic, neem oil, papaya leaves and wood ash could be effectively considered as pest management options to reduce insect pest populations and increase eggplant and okra productivity.