Higher temperatures amplify long-term population cycles in a parasitoid-host system

Background/Question/Methods

Responses of ecosystems to climate warming depend not only on the direct effects of temperature on species, but also on indirect effects acting through species interactions, which empirical studies have shown can be large. These studies, however, are typically short-term (<1 generation), and short-term responses to temperature may be poor predictors of the ultimate changes to dynamics.

Results/Conclusions

We investigated the multi-generation dynamics of pea aphids and a parasitoid, using lab experiments to show that higher temperatures increase population cycles. Additional analyses of 3 years of field data revealed higher aphid population growth rates and increased parasitoid attack rates at higher temperatures, and the observed population cycles in the field qualitatively matched those predicted by models fit to lab data. These results show that, by altering interactions among species, climate change may affect long-term population dynamics, such as the frequency and severity of population outbreaks.