SEASONAL ACTIVITY OF CARABIDS (COLEOPTERA, CARABIDAE) AFFECTED BY MICROBIAL AND OIL INSECTICIDES IN AN APPLE ORCHARD IN CALIFORNIA

The objective of this research was to determine if the seasonal activity of carabid ground beetles was affected by microbial or oil insecticides, which were being used to control the codling moth, Cydia pomonella (L.), a major pest of apple. Plots were sprayed with Bacillus thuringiensis plus oil, oil alone, or codling moth granulosis virus at predicted egg hatchout periods in spring and summer 1991. The results of pitfall trapping indicated that Harpalus pensylvanicus DeGeer adults were significantly more active on the soil surface in plot sprayed with granulosis virus in early July, than in plots sprayed with B. thuringiensis plus oil, or controls (no-spray). Chlaenius sp. (probably C. tricolor Dejean) adults were significantly more active in plots sprayed with oil alone, in early June, than in plots sprayed with granulosis virus, B. thuringiensis plus oil, or controls. The other dominant species, Anisodactylus californicus Dejean, Pterostichus (Hypherpes) spp., Agonum punctiforme Say, and Calathus ruficollis Dejean were not significantly more active in any treatment plot at any of the collection dates. The data suggest that the seasonal activity of two species was probably enhanced by granulosis virus or oil insecticides, whereas the activity of the other dominant species was unaffected.