Douglas-fir dwarf mistletoe (Arceuthobium douglasii) is a parasitic flowering plant that infects Douglas-fir (Pseudotsuga menziesii) throughout the western United States. Douglas-fir dwarf mistletoe induces the formation of witches' brooms on infected trees which alters the biomass and architecture of branches of the infected host. We obtained pairs of broomed and nonbroomed branches of Douglas-fir for sampling and comparing the communities of insects found in each type of branch. Twenty-five families were identified from branches of Douglas-fir, with Chrysomelidae, Phaleothripidae, Pteromalidae, and Braconidae being most common. Richness and totals of insects were one and a half to five times greater in witches' brooms than in nonbroomed branches, respectively. Significantly more Chrysomelidae, Phaleothripidae, Pteromalidae, Miridae, Berytidae, and Braconidae were found on broomed than on nonbroomed branches. However, no significant difference in the structure of the community based on relative abundance was found between broomed and nonbroomed branches. No species of insects was unique to either type of branch. This study represents the first to examine communities of insects in witches' brooms induced by Douglas-fir dwarf mistletoe.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics