Natural occurrence of Nomuraea rileyi on Helicoverpa armigera in pigeonpea ecosystem

A field experiment was conducted to determine the natural occurrence of Nomuraea rileyi (Farlow) Samson on Helicoverpa armigera (Hubner) in pigeonpea ecosystem at Junagadh Agricultural University campus, Junagadh during Kharif seasons of 2008 and 2009. The results revealed that N. rileyi naturally occurred in late August to mid-September and caused the infection in H. armigera larvae up to 14.0% during both the pigeonpea seasons. Its infection was observed maximum during late August and mid-September to late October. Correlation study indicated that the fluctuation in parasitism of H. armigera by N. rileyi showed a strong positive correlation with host density and relative humidity.