البحوث

ABSTRACT

By

Ebtisam Mohammed Bashir Edreiss

 The biological activity of neem oil and the entomopathogenic fungus Metarhizium anisopliae var. acridum, and their combination, were evaluated under laboratory conditions against 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/litre 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 ULV + sprayer. Mortality, body weight, developmental time and deformity were used as parameters to evaluate the efficacy of each product. The effects of neem water extract on the oviposition and egg hatchability were studied as well. The suspension of M. anisopliae caused 90, 58.9, 98.8% mortality on the 3rd, 4th and 5th nymphal instars respectively during the period from the 7th to the 11th day after treatment. The neem oil had shown strong antifeedant action against various instars, the mortality rate was 32.9, 39.9 and 80% on the 3rd, 4th and 5th instar respectively. Also there was a delay in the development period, in addition to deformation and moulting failures. The aqueous extract was used at rate of 25g, 50g and 75g/L water. All concentrations were effective in reducing the egg laying. Also a drastic reduction in egg hatchability were observed in all treatments (19.5, 9.4 and 0.00% hatchability in 25, 50 and 75 g respectively) compared with the control (73.5%). The results of the present study pointed out the potentiality of neem seed extracts and Metarhizium anisopliae in the control of the desert locust Schistocerca gregaria. The practical implications of these results are discussed.

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