INTERACTIONS AMONG SCOLYTID BARK BEETLES, THEIR ASSOCIATED FUNGI, ANDLIVE HOST CONIFERS

Scolytid bark beetles that colonize living conifers are frequently ass ociated with specific fungi that are carried in specialized structures or on the body surface. These fungi are introduced into the tree duri ng the attack process. The continuing association suggests that there is mutual benefit to the fitness of both beetles and fungi. The fungal species may benefit from the association with the beetles by transpor t to new host trees. Beetle species may benefit from the association w ith fungi by feeding on the fungi, or by the fungi contributing to the death of the host trees through mycelial penetration of host tissue, toxin release, interactions with preformed and induced conifer defense s, or the combined action of both beetles and fungi during colonizatio n. Extensive research has been directed towards characterizing the int eractions of beetle-fungal complexes with live host conifers and deter mining the ecological advantages for maintaining the associations. How ever, differences among systems and how species interact under differe nt population and environmental conditions make it difficult to genera lize about the importance of the separate biological components in suc cessful host colonization.