title: Oxygen-limited thermal tolerance is seen in a plastron-breathing insect and can be induced in a bimodal gas exchanger.
abstract: Thermal tolerance has been hypothesized to result from a mismatch between oxygen supply and demand. However, the generality of this hypothesis has been challenged by studies on various animal groups, including air-breathing adult insects. Recently, comparisons across taxa have suggested that differences in gas exchange mechanisms could reconcile the discrepancies found in previous studies. Here, we test this suggestion by comparing the behaviour of related insect taxa with different gas exchange mechanisms, with and without access to air. We demonstrate oxygen-limited thermal tolerance in air-breathing adults of the plastron-exchanging water bug Aphelocheirus aestivalis. Ilyocoris cimicoides, a related, bimodal gas exchanger, did not exhibit such oxygen-limited thermal tolerance and relied increasingly on aerial gas exchange with warming. Intriguingly, however, when denied access to air, oxygen-limited thermal tolerance could also be induced in this species. Patterns in oxygen-limited thermal tolerance were found to be consistent across life-history stages in these insects, with nymphs employing the same gas exchange mechanisms as adults. These results advance our understanding of oxygen limitation at high temperatures; differences in the degree of respiratory control appear to modulate the importance of oxygen in setting tolerance limits.
authors.affiliation: Department of Animal Ecology and Ecophysiology, Institute for Water and Wetland Research, Radboud University, Toernooiveld 1, Nijmegen 6525 ED, The Netherlands Marine Biology and Ecology Research Centre, School of Marine Science and Engineering, University of Plymouth, Davy Building, Drake Circus, Plymouth PL4 8AA, UK wilco@aquaticecology.nl.
authors.forename: Wilco C E P
authors.initials: WC
authors.lastname: Verberk
authors.affiliation: Marine Biology and Ecology Research Centre, School of Marine Science and Engineering, University of Plymouth, Davy Building, Drake Circus, Plymouth PL4 8AA, UK.
authors.forename: David T
authors.initials: DT
authors.lastname: Bilton
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D005618:Fresh Water; D020062:Heteroptera / Q000502:physiology*; D006358:Hot Temperature; D008018:Life Cycle Stages / Q000502:physiology; D010100:Oxygen / Q000378:metabolism; D012119:Respiration
chemical_list: D010100:Oxygen
keywords: Global warming; Heat tolerance; Hypoxia; Multi stressor; OCLTT; Respiration physiology