Cerambycid Communities and Their Associated Hymenopteran Parasitoids From Major Hardwood Trees in Delaware: Implications for Biocontrol of Invasive Longhorned Beetles.

Abstract

Cerambycidae provide important ecological services in forests yet cause economic damage when they infest living trees. Parasitoids can regulate woodborer populations, providing considerable control of pest cerambycids. Identifying parasitoids of native cerambycids may be useful in managing cerambycid outbreaks and aid in new-association biocontrol of exotic invasive cerambycids. We investigated Cerambycidae and associated hymenopteran parasitoid communities infesting Acer rubrum, Pinus virginiana, and Carya tomentosa from a forest in Delaware from 2005 to 2012. Cerambycid abundance, diversity, and richness, as well as parasitoid abundance, were measured by collecting trees in different conditions: felled, girdled, and naturally infested. Effect of edge or interior red maple on cerambycid abundance, diversity, and richness was examined. Over 14,500 cerambycids of 56 species and 38 genera were collected during the 7-yr period. Eleven species represented 95% of all cerambycids collected. Treatment only affected red maple, showing increased cerambycid richness and diversity from naturally infested trees. Cerambycid richness and diversity were two times greater on hickory than other species when combining girdled and felled treatments. Over 19,000 parasitic Hymenoptera of 12 families emerged from woodborer-infested wood with >70% of individuals belonging to Braconidae. Thirteen known species, and two unknown species, of Braconidae were identified from a subsample of 495 specimens; Ontsira mellipes (Ashmead) (Hymenoptera: Braconidae) and Rhoptrocentrus piceus Marshall (Hymenoptera: Braconidae) were the most abundant. This study provides fundamental information on native parasitoids associated with Cerambycidae, including cerambycid larval host associations. Parasitoids identified herein should be investigated for potential adaptation to invasive Cerambycidae to benefit invasive woodborer management.