image: Many insects and arachnids, such as this Indonesian weevil, live at the surface of plants. view more
Credit: Sylvain Pincebourde
A study assesses the vulnerability of leaf-dwelling ectotherms to extreme temperatures. Thermal tolerance limits for ectotherms can vary between contrasting microhabitats and between species within the same microhabitat. To explain the latter observation, Sylvain Pincebourde and Jérôme Casas examined the thermal tolerance limits of six herbivorous arthropods that live and feed on the leaves of the same host plant, as well as the effects of herbivory on leaf transpiration and temperature. Feeding by phloem-feeding arthropods, such as aphids, increased leaf transpiration and reduced leaf surface temperature, whereas feeding by tissue-piercing arthropods, such as mites and lace bugs, reduced transpiration and increased leaf surface temperature. Species' upper thermal limits were correlated with the transpiration rate and temperature of the leaves they attacked, such that species whose feeding decreased transpiration and warmed the leaves could tolerate higher temperatures than species whose feeding increased transpiration and cooled the leaves. Thus, tissue-piercers could tolerate higher temperatures than phloem-feeders, but were also exposed to higher temperatures than phloem-feeders. The difference between each species' upper temperature limit and the warmest temperatures they currently experience was at most 2°C for all species studied. The results suggest that the vulnerability of these species to extreme heat may be much smaller than previously thought, according to the authors.
Article #18-15828: "Narrow safety margin in the phyllosphere during thermal extremes," by Sylvain Pincebourde and Jérôme Casas.
MEDIA CONTACT: Sylvain Pincebourde, University of Tours, FRANCE; tel: +33-2-47-36-69-76, +33-6-59-96-96-26; e-mail: sylvain.pincebourde@univ-tours.fr
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