title: Nitrogen concentration in mountain pine beetle larvae reflects nitrogen status of the tree host and two fungal associates.
abstract: Individual lodgepole pines (Pinus contorta) were fertilized with urea at nitrogen (N) inputs equivalent to 0, 315, or 630 kg/ha. Four months after application of the fertilizer, inner bark tissue N concentrations were significantly higher in the trees that had received the low dose (315 kg/ha) fertilization treatment than in the control trees; trees that had received the high-dose treatment (630 kg/ha) were intermediate and not significantly different from either of the other treatments. There was a significant positive correlation between N concentration in inner bark tissue and larval mountain pine beetle, Dendroctonus ponderosae (Coleoptera: Curculionidae, Scolytinae). In vitro studies on synthetic growth media examined effects of temperature and N concentration on N concentration of two common fungal associates of the mountain pine beetle (Ophiostoma clavigerum and Ophiostoma montium). Increasing N concentration in growth media significantly increased fungal N concentrations in both O. clavigerum and O. montium. Furthermore, N concentration was consistently higher in O. clavigerum than in O. montium. Neither species had sufficient growth at 30 degrees C, nor did O. clavigerum at 15 degrees C, to test N concentration. However, for O. montium, increasing temperatures decreased fungal N concentrations. There was no correlation between N concentration of O. clavigerum and growth temperature. Potential impacts of ingestion of the fungal species by developing mountain pine beetle larvae-infesting trees under various environmental conditions such as increasing temperatures are discussed.
authors.affiliation: Department of Forest Resources, University of Idaho, Moscow, ID 82844-1133, USA. stephenc@uidaho.edu
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Cook
authors.forename: Brian M
authors.initials: BM
authors.lastname: Shirley
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Zambino
mesh_terms: D000818:Animals; D001517:Coleoptera / Q000378:metabolism* / Q000382:microbiology; D006790:Host-Parasite Interactions; D009584:Nitrogen / Q000378:metabolism*; D055156:Ophiostoma / Q000254:growth & development*; D028223:Pinus / Q000378:metabolism* / Q000382:microbiology; D013696:Temperature
chemical_list: D009584:Nitrogen