Bark and ambrosia beetles on native and transplanted dead wood along an altitudinal tropical forest gradient

Global warming is expected to shift the distribution ranges of many species towards higher latitudes and altitudes. This will rewire plant-herbivore food webs as new combinations of herbivore species encounter novel host plants. We investigated the effects of a simulated altitudinal shift in an herbivore-host community of bark and ambrosia beetles on fig trees in a tropical mountain forest on Mt. Wilhelm, Papua New Guinea. We reared beetles from wood baits cut from five local Ficus species in their natural altitudinal ranges, between 200 and 1700 m a. s. l. Further, we transplanted baits from three of these tree species 500 m below the limits of their natural distribution range, to simulate a mean temperature increase of 2.7°C. Beetle species richness declined, and their species composition changed with increasing elevation. Furthermore, while altitude explained a large proportion of variance in beetle composition, host tree species was more important for bark beetles than ambrosia beetles. Beetle communities that assembled on the transplanted baits were similar in diversity and host specificity to those on the fig trees native to the same elevation, but also contained a number of unique species. Overall, these results indicate that saproxylic beetles in this tropical forest are highly resilient and flexible to the potential effects of climate change.

Abstract in Česky is available with online material.