Ecological and Environmental Physiology of Insects

Harrison, Jon F.; Woods, H. Arthur; Roberts, Stephen P.

doi:10.1093/acprof:oso/9780199225941.001.0001

Cited by 183 publications

(176 citation statements)

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“…Indeed, the role of oxygen safety margins (i.e. the difference between P crit and ambient P O2 ) has not been previously considered in experimental assessments of OCLTT, yet it is relatively well established that resting metabolic rate (demand) of many species varies significantly among life stages or throughout development, usually in tandem with changes in oxygen supply capacity (reviewed in Chown and Nicolson, 2004;Harrison et al, 2012). For example, mass-specific VĊ O2 of the silk moth Bombyx mori is 2.5-fold lower in pupae than fifth instar larvae (0.24±0.03 vs 0.64±0.04 ml CO 2 g −1 h −1 ; Blossman-Myer and Burggren, 2010a) and is typical of Lepidoptera species [e.g.…”

Section: Introductionmentioning

confidence: 99%

Oxygen safety margins set thermal limits in an insect model system

Boardman

Terblanche

2015

Journal of Experimental Biology

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A mismatch between oxygen availability and metabolic demand may constrain thermal tolerance. While considerable support for this idea has been found in marine organisms, results from insects are equivocal and raise the possibility that mode of gas exchange, oxygen safety margins and the physico-chemical properties of the gas medium influence heat tolerance estimates. Here, we examined critical thermal maximum (CT max ) and aerobic scope under altered oxygen supply and in two life stages that varied in metabolic demand in Bombyx mori (Lepidoptera: Bombycidae). We also systematically examined the influence of changes in gas properties on CT max . Larvae have a lower oxygen safety margin (higher critical oxygen partial pressure at which metabolism is suppressed relative to metabolic demand) and significantly higher CT max under normoxia than pupae (53°C vs 50°C). Larvae, but not pupae, were oxygen limited with hypoxia (2.5 kPa) decreasing CT max significantly from 53 to 51°C. Humidifying hypoxic air relieved the oxygen limitation effect on CT max in larvae, whereas variation in other gas properties did not affect CT max . Our data suggest that oxygen safety margins set thermal limits in air-breathing invertebrates and the magnitude of this effect potentially reconciles differences in oxygen limitation effects on thermal tolerance found among diverse taxa to date.

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Section: Introductionmentioning

confidence: 99%

Oxygen safety margins set thermal limits in an insect model system

Boardman

Terblanche

2015

Journal of Experimental Biology

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“…Body size and metabolic rate respond to pO 2 when insects are reared in hypoxic or hyperoxic atmospheres (7,8), although the effects are not uniform in all taxa (9). Flying insects should be particularly susceptible to variations in atmospheric pO 2 because their flight musculature has high energy demands (10), particularly during periods of active flight (11,12). The volume occupied by tracheae, tubes that transport oxygen throughout the body, scales hypermetrically with body volume, imposing further surface area-to-volume constraints on maximum size (13,14).…”

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confidence: 99%

Environmental and biotic controls on the evolutionary history of insect body size

Clapham

Karr

2012

Proc. Natl. Acad. Sci. U.S.A.

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Giant insects, with wingspans as large as 70 cm, ruled the Carboniferous and Permian skies. Gigantism has been linked to hyperoxic conditions because oxygen concentration is a key physiological control on body size, particularly in groups like flying insects that have high metabolic oxygen demands. Here we show, using a dataset of more than 10,500 fossil insect wing lengths, that size tracked atmospheric oxygen concentrations only for the first 150 Myr of insect evolution. The data are best explained by a model relating maximum size to atmospheric environmental oxygen concentration (pO 2 ) until the end of the Jurassic, and then at constant sizes, independent of oxygen fluctuations, during the Cretaceous and, at a smaller size, the Cenozoic. Maximum insect size decreased even as atmospheric pO 2 rose in the Early Cretaceous following the evolution and radiation of early birds, particularly as birds acquired adaptations that allowed more agile flight. A further decrease in maximum size during the Cenozoic may relate to the evolution of bats, the Cretaceous mass extinction, or further specialization of flying birds. The decoupling of insect size and atmospheric pO 2 coincident with the radiation of birds suggests that biotic interactions, such as predation and competition, superseded oxygen as the most important constraint on maximum body size of the largest insects.paleoecology | temperature | maximum likelihood estimation B ecause metabolic oxygen demand increases with increasing body size, environmental oxygen concentration (pO 2 ) is frequently invoked as an important constraint on the size of animals (1-6). Giant late Paleozoic insects, with wingspans as large as 70 cm, are the iconic example of the oxygen-body size link; hyperoxic conditions during the Carboniferous and Permian are thought to have permitted the spectacular sizes of the largest insects ever (2, 4). The physiological basis linking insect body size and pO 2 has been elucidated in numerous experimental tests (5,7,8). Body size and metabolic rate respond to pO 2 when insects are reared in hypoxic or hyperoxic atmospheres (7,8), although the effects are not uniform in all taxa (9). Flying insects should be particularly susceptible to variations in atmospheric pO 2 because their flight musculature has high energy demands (10), particularly during periods of active flight (11, 12). The volume occupied by tracheae, tubes that transport oxygen throughout the body, scales hypermetrically with body volume, imposing further surface area-to-volume constraints on maximum size (13,14).Although these responses underscore the physiological importance of oxygen, developmental plasticity exhibited by different insect groups may not be indicative of evolutionary changes (15), especially in natural settings where other abiotic influences, biotic interactions, and selective pressure from allometric scaling of life-history traits are also important (16)(17)(18)(19)(20). For example, temperature can also be an important influence on insect body size via physiologica...

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“…Future studies could also help understand possible benefits and disadvantages of black pupal colour in L. cervi. Dark surface colouration may for example represent an adaptive thermoregulatory trait if the dark colouration enables to better absorb short-wave solar radiation and thus attain higher body temperature during cold times and also aid snow burying capacity (Harrison et al 2012).…”

Section: Discussionmentioning

confidence: 99%

Passive sinking into the snow as possible survival strategy during the off-host stage in an insect ectoparasite

Kaunisto

Ylönen

Kortet

2015

Folia Parasitologica

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Abiotic and biotic factors determine success or failure of individual organisms, populations and species. The early life stages are often the most vulnerable to heavy mortality due to environmental conditions. The deer ked (Lipoptena cervi Linnaeus, 1758) is an invasive insect ectoparasite of cervids that spends an important period of the life cycle outside host as immobile pupa. During winter, dark-coloured pupae drop off the host onto the snow, where they are exposed to environmental temperature variation and predation as long as the new snowfall provides shelter against these mortality factors. The other possible option is to passively sink into the snow, which is aided by morphology of pupae. Here, we experimentally studied passive snow sinking capacity of pupae of L. cervi. We show that pupae have a notable passive snow sinking capacity, which is the most likely explained by pupal morphology enabling solar energy absorption and pupal weight. The present results can be used when planning future studies and when evaluating possible predation risk and overall survival of this invasive ectoparasite species in changing environmental conditions.

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Ecological and Environmental Physiology of Insects

Cited by 183 publications

References 0 publications

Oxygen safety margins set thermal limits in an insect model system

Oxygen safety margins set thermal limits in an insect model system

Environmental and biotic controls on the evolutionary history of insect body size

Passive sinking into the snow as possible survival strategy during the off-host stage in an insect ectoparasite

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