PARENT SESSION
Poster Session #37: Invertebrate Ecology.
Thursday, August 9, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall
75
Fungal associates of an eruptive tree-killing phloeophagous herbivore.
Haberkern, Kirsten1, Illman, Barbara2, Werner, Richard3, Raffa, Kenneth1, 1 2 3
ABSTRACT- Bark beetles are eruptive herbivores that cause extensive natural disturbances, and affect ecosystem and landscape processes, such as succession, fire, gap formation, and nutrient cycling. The population dynamics of these phloeophagous insects are influenced by weather, host resistance, and natural enemies, but underlying causes of regionwide eruptions remain only partly understood. Bark beetles show close associations with fungi, whose effects on their vectors range from mutualistic to antagonistic. The spruce beetle, Dendroctonus rufipennis, has caused mortality to several million hectares of pure spruce stands throughout Alaska and western Canada. This research reports the first of a two–phase study: 1) Characterizing the fungal associates of D. rufipennis and a related species rarely associated with tree-killing, Ips perturbatus, and 2) quantifying sources of variation in these fungi, with emphasis on potential differences between eruptive and endemic populations. Study sites were located near Fairbanks and on the Kenai Peninsula. Beetles were collected from host trees and pheromone traps during 1999 and 2000. Fungi were isolated on selected medium using two methods: rolling live insects, and applying dilutions of water and crushed insects. The major fungi associated with D. rufipennis were Leptographium abietinum, Ophiostoma piceae,O. ips, and O. olivaceum. The major fungi associated with Ips perturbatus were L. abietinum, O. piliferum, and O. nigrocarpum. Preliminary evidence suggests some differences in the composition of fungal associates of D. rufipennis among population phases.
KEY WORDS: bark beetles, fungi, Dendroctonus rufipennis, symbiosis