Effects of elevated CO2 and temperature on the performance of a diet specialized Neotropical herbivore and its host plant

Authors: VENCL, FREDRIC - Stoneybrook University; BARTRAM, STEFAN - Max Planck Institute Of Chemical Ecology; WINTER, KLAUS - Smithsonian Tropical Research; BOLAND, WILHELM - Max Planck Institute Of Chemical Ecology; Srygley, Robert

Submitted to: Biotropica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/4/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Elevated [CO2] and temperature caused declines in host quality and larval survivorship There are no investigations quantifying the impact of climate change stressors, working independently or in concert, on specialized plant-herbivorous insect interactions for denizens of the rapidly expanding tropical forest edge ecotone. ARS Researchers at Sidney, Montana conducted research on hogvine, an invasive edge specialist disrupting agroforestry in the Paleotropics, and an herbivorous beetle for which the vine is its sole host. Leaf expansion rate and plant biomass more than doubled with experimental doubling of ambient [CO2]. Elevated [CO2] combined with a 4°C elevation of ambient temperature resulted in an increase of leaf C:N, which was greater than the additive effects of each factor alone. Moreover, climate stressors interacted to significantly reduce beetle performance and survivorship as one would expect from the decrease in forage quality. More studies of tropical plant-insect interactions need to be conducted in projected future climate scenarios, but from this first study in the tropics, hogvine will benefit from elevation of atmospheric carbon and temperature, altering plant chemistry and disrupting herbivory by a specialized beetle.

Technical Abstract: Little is known about the potential responses of ecologically specialized tropical species to atmospheric change and global warming. In greenhouse experiments simulating climate change impacts, we quantified the effects of mean ambient temperature (Ta), elevated temperature (Te), current ambient CO2, and doubled CO2 levels on biomass, growth rate, and foliar chemistry of the morning glory vine, Camonea umbellata. In addition, we measured the impacts of climate change simulations on the performance and survival of the tortoise beetle, Acromis sparsa, which feeds exclusively on Camonea. Vines growing in doubled [CO2] more than doubled their biomass and leaves expanded faster. Whereas ambient [CO2] and Te interacted to yield the greatest foliar [C], vines in doubled [CO2] and Te had the greatest C:N ratio and the lowest availability of nitrogen, which was associated with increased larval mortality. Moreover, pupae were smaller and suffered lower survival in Te, while doubled [CO2] interacted with Te to increase pupal mass and survival. Elevation of both [CO2] and temperature caused declines in host quality, larval survivorship and pupal mortality that were not observed when only one climate factor was altered. Based on this first tropical study, we predict that Camonea will benefit from elevation of temperature and atmospheric CO2 by altering its foliar chemistry to the detriment of its diet-specialized herbivore enemy.