The natural incidence of disease in the cutworm Agrotis segetum in England and Wales

Soil-dwelling noctuids, mostly cutworm larvae were collected from various arable crops, from 39 sites in England and Wales between 1975 and 1978. They were individually reared in the laboratory, usually at 20 °C; 993 (79%) pupated and 859 (68%) emerged of which 819 (95%) were Agrotis segetum. Of those that died, 60 (4·8%) were infected, from a total of 25 sites; nuclear polyhedrosis, granulosis virus and a fungus of the family Entomophthoracae, probably Entomophthora megasperma, occurred in similar proportions. Disease incidence was low probably because natural concentrations of inocula were sparse. The possibility of controlling cutworms with their pathogens is discussed.