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Abstract Species interactions are expected to change in myriad ways as the frequency and magnitude of extreme temperature events increase with anthropogenic climate change.The relationships between endosymbionts, parasites and their hosts are particularly sensitive to thermal stress, which can have cascading effects on other trophic levels.We investigate the interactive effects of heat stress and parasitism on a terrestrial tritrophic system consisting of two host plants (one common, high‐quality plant and one novel, low‐quality plant), a caterpillar herbivore and a specialist parasitoid wasp.We used a fully factorial experiment to determine the bottom‐up effects of the novel host plant on both the caterpillars' life history traits and the wasps' survival, and the top‐down effects of parasitism and heat shock on caterpillar developmental outcomes and herbivory levels.Host plant identity interacted with thermal stress to affect wasp success, with wasps performing better on the low‐quality host plant under constant temperatures but worse under heat‐shock conditions.Surprisingly, caterpillars consumed less leaf material from the low‐quality host plant to reach the same final mass across developmental outcomes.In parasitized caterpillars, heat shock reduced parasitoid survival and increased both caterpillar final mass and development time on both host plants.These findings highlight the importance of studying community‐level responses to climate change from a holistic and integrative perspective and provide insight into potential substantial interactions between thermal stress and diet quality in plant–insect systems. Read the freePlain Language Summaryfor this article on the Journal blog.
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Additive and interactive effects of anthropogenic stressors on an insect herbivore
The pressures of global change acting on wild plants and animals include exposure to environmental toxins, the introduction of non-native species, and climate change. Relatively few studies have been reported in which these three main classes of stressors have been examined simultaneously, allowing for the possibility of synergistic effects in an experimental context. In this study, we exposed caterpillars of the Melissa blue butterfly ( Lycaeides melissa ) to three concentrations of chlorantraniliprole, under three experimental climates, on a diet of a native or a non-native host plant throughout larval development in a fully factorial experiment. We find that high pesticide exposure and a non-native diet exhibit strong negative effects on caterpillars, resulting in 62% and 42% reduction in survival, respectively, while interactive effects tend to be weaker, ranging from 15% to 22% reduction in survival. Interactive effects have been shown to be strong in other contexts, but do not appear to be universal; however, our study shows that the cumulative effects of stressors acting in isolation (additively) are sufficiently strong to severely reduce survival and by extension population persistence in the wild.
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- Award ID(s):
- 2114793
- PAR ID:
- 10447797
- Date Published:
- Journal Name:
- Proceedings of the Royal Society B: Biological Sciences
- Volume:
- 290
- Issue:
- 1996
- ISSN:
- 0962-8452
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1098/rspb.2022.2431
