Pine terpenoid defences in the mountain pine beetle epidemic and in other conifer pest interactions: specialized enemies are eating holes into a diverse, dynamic and durable defence system

In summary, while a tree-centric perspective may have been prevailing for some time in the literature on conifer defence systems, bark beetles and fungi can eat some painful holes into simplified concepts of terpenoid defences of pines. While terpenoid defences are diverse, dynamic and often durable, through the evolution of specialist beetles and fungi, they also present a source of attractive information, signals and food for the tree’s most ferocious natural enemies. In addition, terpenes are also an ideal biofuel of hydrocarbons which, in nature, let pine forests easily go up in flames (Bohlmann 2011). A high content of flammable terpene hydrocarbons may also increase fire hazards in saw mills now processing massive amounts of MPB-killed pines.