Laboratory evaluation of the effects of neem (Azadirachta indica) oil and Metarhizium anisopliae against some immature stages of the desert locust Schistocerca gregaria

Abstract

The biological activity of neem (Azadirachta indica A. Juss) oil and the entomopathogenic fungus Metarhizium anisopliae var. acridum (Deuteromycotina: Hyphomycetes), and their combination, were evaluated under the conditions of the Insectary of the Department of Crop Protection, Faculty of Agriculture, University of Khartoum against the 3rd, 4th and 5th nymphal instars of the desert locust (Schistocerca gregaria). The test products were used at concentration of 8 ml/L water (for neem oil) and 25 g powder/L diesel (for the fungus), and for combination treatment (8 ml neem oil plus 25 g of Metarhizium anisopliae). All products were applied topically on the test insects using Ultra low volume (ULVA+) spraying. Mortality, body weight, developmental time and morphological anomalies were used as parameters to evaluate the efficacy of each product. The suspension of M. anisopliae caused 90, 58.9, and 98.8% mortality on the 3rd, 4th and 5th nymphal instars, respectively, during the period from the 7th to the 11th day post-treatment. The neem oil had shown strong antifeedant action against the various instars, and a mortality rate of 32.9, 39.9 and 80% on the 3rd, 4th and 5th instars, respectively. Also, there was a delay in the development period, in addition to deformation and moulting failures