Efficacy of a Cladosporium sp. fungus against Helicoverpa armigera (Lepidoptera: Noctuidae), other insect pests and beneficial insects of cotton

Abstract

A strain of the fungus Cladosporium sp. (RM16) from an egg of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) was assessed as a potential biocontrol agent for this pest. Pathogenicity of the fungus was tested against H. armigera eggs and larvae, cotton aphids (Aphis gossypii Glover; Homoptera: Aphididae), and silverleaf whitefly type B (Bemisia tabaci Gennadius; Hemiptera: Aleyrodidae). The pathogenicity of the fungus to the predatory red and blue beetles (Dicranolaius bellulus Guérin-Méneville; Coleoptera: Melyridae), transverse ladybird beetles (Coccinella transversalis Fabricius; Coleoptera: Coccinellidae), green lacewings (Mallada signatus Schneider; Neuroptera: Chrysopidae) and damsel bugs (Nabis kinbergii Reuter; Hemiptera: Nabidae), was also assessed in the laboratory. Fungus treatment resulted in failure to hatch of up to 64% of H. armigera eggs (compared with 11% in the controls) and mortality of 54% of first instar H. armigera larvae (compared with 5% in the controls). In contrast, it was not pathogenic to later instar H. armigera larvae. Cladosporium RM16 was also efficacious against the sap-sucking insect pests of cotton that were tested. No significant harmful effect of the fungus was found on any of the four beneficial predatory insects assessed in this study. Cladosporium RM16 has the potential as biological control agent to support integrated pest management in cotton farming systems, although this needs intensive study.