PREY SELECTION AND BACULOVIRUS DISSEMINATION BY CARABID PREDATORS OF LEPIDOPTERA

1. The interaction between coleopteran predators and baculovirus-infec ted larvae was studied in the laboratory and the field in order to ass ess the potential role of predators in the dissemination of a nucleopo lyhedrovirus (NPV). 2. Preference tests using three carabid species, H arpalus rufipes De Geer, Pterostichus melanarius Illiger and Agonum do rsale Pont. showed no evidenee of discrimination between healthy and d iseased larvae of the cabbage moth Mamestra brassicae L. (Lepidoptera: Noctuidae) as prey items. 3. Virus infectivity was maintained after p assage through the predator's gut. NPV mortality ranged from 97% to 20 % when test larvae were exposed to faeces collected immediately after and 15 days post-infected meal respectively. 4. The potential for tran sfer of inoculum in the environment was estimated in the laboratory by soil bioassay. Carabids continuously passed infective virus to the so il for at least 15 days after feeding on infected larvae. 5. Field exp eriments showed that carabids which had previously fed on diseased lar vae transferred sufficient virus to the soil to cause low levels of mo rtality in larval populations of the cabbage moth at different instars .