Insect-microbe interactions mediate the success of biological control and response to climate change

There is a growing body of knowledge on the effects of climate change on pest species but less is known about the impacts of elevated temperatures on complex insect-microbe interactions that can determine the success of biological control.  This paper reports findings from an Australian biological control system in which fungal symbionts play important roles in insect-plant interactions. The fungus, Ophiostoma ips is associated with Ips beetles whilst a second fungus, Amylostereum areolatum is associated with sirex woodwasp. The latter fungus is important in biological control of sirex because  the nematode agent, B. siricidicola, is able to feed and reproduce on a diet of the fungus alone in the absence of the host insect. Studies in artificial media and using wood discs showed that O. ips grows more rapidly at elevated temperature and denies A. areolatum substrate. In contrast, growth of A. areolatum is not accelerated at elevated temperature. Findings from these studies show that the interactions between the two fungi explain why biological control of sirex is less effective when Ips beetles are present and suggest that such disruption will be exacerbated under climate change conditions.