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' Hubner (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' Guerin-Meneville; '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.