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Humidity modifies species‐specific and age‐dependent heat stress effects in an insect host‐parasitoid interaction

Dongbo Li Orcid Logo, Benjamin Brough, Jasper W. Rees, Christophe Coste, Chenggui Yuan Orcid Logo, Mike Fowler Orcid Logo, Steven M. Sait Orcid Logo

Ecology and Evolution, Volume: 14, Issue: 7, Start page: e70047

Swansea University Authors: Christophe Coste, Chenggui Yuan Orcid Logo, Mike Fowler Orcid Logo

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DOI (Published version): 10.1002/ece3.70047

Abstract

Climate change is projected to increase the frequency and intensity of extreme heat events, and may increase humidity levels, leading to coupled thermal and hydric stress. However, how humidity modulates the impacts of heat stress on species and their interactions is currently unknown. Using an inse...

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Published in: Ecology and Evolution
ISSN: 2045-7758 2045-7758
Published: Wiley 2024
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URI: https://cronfa.swan.ac.uk/Record/cronfa67171
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Abstract: Climate change is projected to increase the frequency and intensity of extreme heat events, and may increase humidity levels, leading to coupled thermal and hydric stress. However, how humidity modulates the impacts of heat stress on species and their interactions is currently unknown. Using an insect host-parasitoid interaction: the Indian meal moth, Plodia interpunctella, and its endoparasitoid wasp, Venturia canescens, we investigated how humidity interacted with heat stress duration, applied at different host developmental stages, to affect life history traits. Hosts parasitized as 4th instar larvae and unparasitized hosts were maintained in high- (60.8% RH) or low-humidity (32.5% RH) at constant 28°C. They were then exposed to a 38°C thermal stress with a duration of 0 (no heat stress), 6 or 72 h in either the 4th or 5th host instar. Neither humidity nor heat stress duration affected emergence of unparasitized hosts, but increasing heat stress duration during the 4th instar decreased parasitoid emergence irrespective of humidity. When applied during the 5th instar, increasing heat duration decreased parasitoid emergence under low humidity, but no effect of heat stress was found under high humidity. Moreover, experiencing longer heat stress in the 4th instar increased host larval development time and decreased body size under high humidity, but this effect differed under low humidity; increasing heat duration in the 5th instar decreased parasitoid body sizes only under low humidity. Larval stage and heat stress duration directly affected parasitized host survival time, with a concomitant indirect reduction of parasitoid sizes. We show that humidity modifies key life history responses of hosts and parasitoids to heat stress in species-specific ways, highlighting the potential importance of humidity in regulating host-parasitoid interactions and their population dynamics. Finally, we emphasize that interactions between environmental stressors need to be considered in climate change research.
Keywords: bottom-up effect, environmental stress, extinction, insect decline, phenotypic traits, species interactions
College: Faculty of Science and Engineering
Funders: NERC
Issue: 7
Start Page: e70047