HYMENOPTEROUS PARASITES OF IPS PARACONFUSUS (COLEOPTERA: SCOLYTIDAE) LARVAE AND THEIR CONTRIBUTION TO MORTALITY: I. INFLUENCE OF HOST TREE AND TREE DIAMETER ON PARASITIZATION

Abstract

AbstractThe larval parasite complex of Ips paraconfusus Lanier is found to differ in Pinus ponderosa and Pinus lambertiana within the same local area. Ips paraconfusus was attacked by fewer species of parasites in ponderosa pine and the rate of parasitization was generally less in that tree species. Greater parasitization in sugar pine was not entirely accounted for by the additional parasite species, but also reflected greater efficacy by those species common to both trees. Evidence indicates that greater bark thickness in ponderosa pine at comparable diameters may have been responsible for the higher parasitization by the shared parasite species.A significant negative regression of parasitization with diameter was found in sugar pine, but not in ponderosa pine. Most, if not all, of this regression is attributed to a single species, Rhopalicus pulchripennis, whose searching appears to be confined to the smooth, softer bark of the crown.