Effect of Alternaria alternata on the coccinellid pest Henosepilachna vigintioctopunctata and its implications for biological pest management

摘要

Twenty-eight spotted potato ladybird beetle (Henosepilachna vigintioctopunctata) is a polyphagous pest that infests various crop plants of the family Solan-ceae. It extensively infests Withania somnifera, a high-value medicinal plant of this family. Both the beetle and W. somnifera leaf spot pathogen (Alternaria alternata) are individually found to be closely associated with the foliar damage and may rarely infest the same leaf simultaneously. Beetles fed on diseased leaves showed high pupal and larval mortality. Furthermore, the development of the larvae into pupa and from pupa to adult was also delayed, which in turn delayed the overall development of the insect. Adult emergence from pupae is also reduced in the insects fed on diseased leaves. Since the fungal pathogen is host specific to W. somnifera and does not infect the other solanaceous crops, therefore this fungal stain can be used in designing bio-control strategies for the other solanaceous plants frequently infested by the beetle.