Abstract:

Primary resistance of host trees directly effects the infection of bark beetles, secondary resistance of host trees restrict the colonization and brood development of bark beetles in the host tree tissues.The resistance of host trees decides invasion number of bark beetles and impels bark beetles to symbioses with special fungi. The symbiotic fungi of bark beetles effect the physiological metabolism of host trees to weaken host trees resistance, so that, creating essential existance condition for bark beetles in the host tree tissues, and inducing existance strategy of bark beetles' high evolution in suitable to the symbiotic fungi and host trees resistance, result in bark beetles cooperated evolution with host trees and symbiotic fungi.

Key words: Bark beetles, Symbiotic fungi, Existance strategy, Resistance, Evolution