Efficacy of certain natural compounds and entomopathogenic fungi compared with malathion against cowpea beetle, Callosobruchus maculatus (Fabricius) under laboratory conditions [electronic resource]

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Cowpea beetle, Callosobruchus maculatus (Fabricius) (Coleoptera: Chrysomelidae) is one of the most dangerous insect pests in field and storage. It causes a high damage to the legumes by decreased dietary values, germination and seed weights. Using synthetic insecticides for controlling stored grain pests have a lot of problems for humans and environment. Therefore, the mixing seeds laboratory experiments were conducted to study the efficacy of certain alternative safety compounds against C. maculatus such as Beauveria bassiana, Metarhizium anisopliae, ascorbic acid, boric acid, talc powder and kaolin compared with an organophosphorus nervous insecticide, malathion 1% dust, that recommended in Egypt for controlling stored grain pests. The present results showed that the malathion was the highest toxicity effect against cowpea beetle adults with LC50(3.89 ppm) after 3-day post treatment. However, the boric acid was the lowest toxicity effect with LC50 (72855 ppm) after 6 days post treatment. The other tested materials showed moderate effects. These results indicate that malathion is still having high effect against cowpea beetle. The toxicity of bio-insecticides (M. anisopliae and B. bassiana) after 6days were more than toxicity malathion 1%dust after 1day.Wheraes, the toxicity of bio-insecticides (M. anisopliae and B. bassiana) increased with increase of period of exposure from 2 to 6 days high rates about 28 times, 31 times, respectively. The findings showed that the tested compounds have a promising insecticidal activity against C. maculatus and can be used as possible alternatives to synthetic chemical insecticides such as malathion for the control of stored product insects.
Keywords: Callosobruchus maculatus, Malathion, Entomopathogenic fungi.

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