Differing thermal sensitivities in a host–parasitoid interaction: High, fluctuating developmental temperatures produce dead wasps and giant caterpillars

Insect parasitoids, and the arthropod hosts they consume during development, are important ecological players in almost all environments across globe. As ectothermic organisms, both parasitoid host strongly impacted by environmental temperature. If thermal tolerances differ between insect parasitoid, then outcome of their interaction will be determined ambient mean temperatures continue to rise extreme become more frequent, we must determine effect high temperature stress on host–parasitoid systems predict how fare face climate change. The majority studies conducted focus either performance under constant or a fixed metric tolerance (CTmax) for individual organisms. However, at is not predictive ecologically relevant, fluctuating measurements thresholds provide little information regarding effects throughout development. We address this testing increasing (±10°C) development wasp Cotesia congregata its lepidopteran larval host, Manduca sexta. growth M. sexta was influenced temperature, diurnal fluctuations parasitization status. Caterpillar rate increased with but decreased response C. wasps. Wasp survival fluctuations. stronger higher temperatures. Diurnal our highest treatment (30 ± 10°C) resulted complete mortality, parasitized displayed abnormal physiology, wherein failed exhibit emergence, did enter prepupal stage, continued feed grew up twofold larger than normal, unparasitized caterpillar. Our results indicate parasitoids system have different development; suffered mortality regime that mildly stressful caterpillar species. findings suggest suffer severely sexta, cascading trophic effects. A free Plain Language Summary can found within Supporting Information article.