INFLUENCE OF BIORA TIONAL INSECTICIDES ON PARASITOID SPECIES ASSOCIATED WITH FALL ARMYWORM, SPODOPTERA FRUGIPERDA (J. E. SMITH)

Abstract

The use of synthetic insecticides for the control of fall armyworm (FA W), Spodoptera Jrugiperda (J. E. Smith), poses significant dangers to human health and the environment, hence the need to explore biological control options in combating this pest. On-farm and on-station studies were conducted to evaluate the influence ofbio-rational insecticides on parasitoid fauna and their effect on damage incidence of FA W in maize in the savannah ecology of Ghana. Maize farms totalling 91 were selected for the on-farm study. The on station experiment was laid out in RCBD with five replications. The bio-rational insecticides applied were Grow-safe neem seed oil (3% azadirachtin), Bypel 1 (Perisrapae granulosis virus + Bacillus thuringiensis), Agoo (Bacillus thuringiensis 55% + Monosultap), Eradicoat (Maltodextrin), Ema Star (Emamectin benzoate + acetamiprid) and untreated controls. Samples of FA W egg masses and larvae collected from the field were incubated to determine the parasitoid species emerged, their relative abundance and parasitism rate. The results showed seven parasitoid species associated with FA W. These were Coccygidium luteum, Chelonus sp., Charops sp., Cotesia icipe and Sharops sp. The parasitism rates recorded in the on-farm and on-station were 9.18% and 22.99%, respectively. C. luteum had the highest parasitism rate and relative abundance in both trials followed by Chelonus sp. Among the insecticides, Bypel 1 recorded the lowest parasitism rate in both trials. Fall armyworm damage in maize was significantly affected by both sampling dates and insecticide treatments, but there was no significant interactions. Combating the fall armyworm menace in the savanna zone of Ghana should focus on the exploitation of these key indigenous parasitoid for bio-control interventions.