The present study investigated the insecticidal activity of the different organic extracts from the entomopathogenic fungi, Cladosporium cladosporioides, Metarhizium anisopliae, Purpureocillium lilacinum, and Trichoderma longibrachiatum towards cotton aphid, Aphis gossypii. The methanol extracts from the mycelia and spores of C. cladosporioides and P. lilacinum exhibited the highest insecticidal activity against A. gossypii compared with other extracts, which LC50 values were recorded to be 57.60 and 94.18 ppm, respectively. The major constituents identified in both methanol extracts by GC-MS analysis were linoleic acid and palmitic acid. The methanol extracts of C. cladosporioides and P. lilacinum caused a voluminous increase in the total carbohydrates content of A. gossypii adults, while the total protein content was significantly decreased by both extracts. The activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were significantly reduced by methanol extracts. The P. lilacinum extract caused a considerable reduction in the activity of glutathione-S-transferase (GST), α- and β-esterase by 28.9, 27.9 and 23.4%, respectively. Both extracts induced a significant increase in phenoloxidase and chitinase activity of A. gossypii adults. These results suggest that C. cladosporioides and P. lilacinum methanol extracts could be used as a promising approach for the management of A. gossypii in many economically crops.
Keywords: Aphis gossypii; Biological control; Enzymes activity; Fungal metabolites; GC–MS, biochemical characteristics.
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