Desiccation resistance and water balance in southern African keratin beetles (Coleoptera, Trogidae): the influence of body size and habitat

Lagadec, M. D. Le; Chown, Steven L.; Scholtz, Clarke H.

doi:10.1007/s003600050127

Cited by 67 publications

(62 citation statements)

References 31 publications

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“…That is, metabolic rate was retained as a significant term (partial correlation t=4.3, P<0.05). Indeed, although larger body size has frequently been identified as an important means by which insects in general (Schoener and Janzen, 1968;Remmert, 1981;Lighton et al, 1994;Le Lagadec et al, 1998; but see also Gibbs and Matzkin, 2001;Chown and Klok, 2003;Gibbs et al, 2003), and dung beetles in particular (Chown et al, 1995), might alter their responses to environmental water availability, it did not enter most of our models as a significant term. Clearly, both cuticular and spiracular water loss rates scale with body mass, but, especially in the latter case, body mass is much less important in explaining variation than are other factors.…”

Section: Discussionmentioning

confidence: 95%

Discontinuous gas exchange and the significance of respiratory water loss in scarabaeine beetles

Chown

Davis

2003

Journal of Experimental Biology

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SUMMARYRespiratory water loss in insects is a controversial topic. Whilst earlier studies considered respiratory transpiration a significant component of overall water loss, to the extent that it was thought to be responsible not only for the evolution of discontinuous gas exchange cycles (DGCs) but also for variation in DGC patterns, later work repeatedly questioned its importance. In particular, investigations of the proportional contribution of respiratory transpiration to total water loss in species showing DGCs suggested that respiratory transpiration was unlikely to be important in these species. In turn, these studies have been criticized on analytical grounds. In this study we investigated variation in cuticular and respiratory water loss rates in five Scarabaeus dung beetle species, all of which show discontinuous gas exchange cycles, to ascertain the significance of respiratory water loss using modern analytical techniques. In particular, we determined whether there is variation in water loss rates amongst these beetles, whether both respiratory and cuticular water loss rates contribute significantly to variation in the former, and whether metabolic rate variation and variation in the duration of the DGC periods contribute significantly to variation in respiratory water loss rate. Total water loss rate varied such that species from arid areas had the lowest rates of water loss, and both cuticular and spiracular transpiration contributed significantly to variation in overall water loss rate. Moreover, variation in metabolic rate and in the duration of the DGC periods contributed significantly to variation in respiratory water loss rate. By contrast, examination of proportional water loss revealed little other than that it varies between 6.5% and 21%, depending on the species and the temperature at which it was examined. Cuticular water loss scaled as mass0.721, but did not differ from that expected from geometric considerations alone. By contrast, respiratory water loss scaled as mass0.531, suggesting that gas exchange takes place by diffusion and convection. Our results provide direct evidence that respiratory water loss forms a significant component of water balance, and that changes in both metabolic rate and DGC characteristics contribute to modulation of respiratory water loss.

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Section: Discussionmentioning

confidence: 95%

Discontinuous gas exchange and the significance of respiratory water loss in scarabaeine beetles

Chown

Davis

2003

Journal of Experimental Biology

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“…It is also interesting that adult A. diaperinus cannot survive on a dry diet, unlike some other insects (Naidu & Hattingh, 1988;Scholtz & Caveney, 1988). The utilization of lipid catabolism as a means to provide a source of water, as found in keratin beetles (Le Lagadec et al, 1998), may be limited in A. diaperinus.…”

Section: Resultsmentioning

confidence: 99%

“…The slight, but not significant, slower rate of water loss in females is likely to be related to their larger body size and may contribute to the better survival of females. Moreover, larger insects could tolerate greater water losses than smaller ones because of the higher amount of water that can be lost (Le Lagadec et al, 1998).…”

Section: Importance Of Sex and Body Sizementioning

confidence: 99%

Water loss of male and female Alphitobius diaperinus (Coleoptera: Tenebrionidae) maintained under dry conditions

Renault¹,

Coray²

2004

Eur. J. Entomol.

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Abstract. Survival under dry conditions was examined in males and females of Alphitobius diaperinus Panzer (Coleoptera: Tenebrionidae), a beetle of tropical origin. The range of individual responses and the effect of gender on water loss were also evaluated. Females exhibit significantly longer survival (Lt50 and Lt90) than males under desiccating conditions. Larger females beetles have a greater initial water mass and hence can tolerate greater water losses. Such beetles have longer survival under dry conditions. Males and females loose an average of 54.8 and 58.9% of their body water prior to death. The insects were inactive most of the time, when kept under dry conditions; the rate of decrease in body water was thus reduced. Beetles of both gender display a negative correlation between the rates of water loss under desiccating conditions and the duration of survival. We conclude that the difference in survival period between males and females is due to a combination of greater female tolerance to desiccation and larger body size.

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“…the rate measured at the interval prior to dead). To correct the analyses for the individual variation in mass and water status and to account for potential sex-specific differences in the response variables (see Chown and Nicolson, 2004;Le Lagadec et al, 1998), initial M s and sex were included as covariates, plus WC s in the analysis of WLRs. In this case, as M s and WC s are highly correlated, their effects were evaluated separately to avoid statistical problems of collinearity between predictors.…”

Section: Effect Of Salinity On Desiccation Resistancementioning

confidence: 99%

Aquatic insects in a multistress environment: cross-tolerance to salinity and desiccation

Pallarés

Botella‐Cruz

Arribas

et al. 2017

Journal of Experimental Biology

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Exposing organisms to a particular stressor may enhance tolerance to a subsequent stress, when protective mechanisms against the two stressors are shared. Such cross-tolerance is a common adaptive response in dynamic multivariate environments and often indicates potential co-evolution of stress traits. Many aquatic insects in inland saline waters from Mediterranean-climate regions are sequentially challenged with salinity and desiccation stress. Thus, cross-tolerance to these physiologically similar stressors could have been positively selected in insects of these regions. We used adults of the saline water beetles Enochrus jesusarribasi (Hydrophilidae) and Nebrioporus baeticus (Dytiscidae) to test cross-tolerance responses to desiccation and salinity. In independent laboratory experiments, we evaluated the effects of (i) salinity stress on the subsequent resistance to desiccation and (ii) desiccation stress (rapid and slow dehydration) on the subsequent tolerance to salinity. Survival, water loss and haemolymph osmolality were measured. Exposure to stressful salinity improved water control under subsequent desiccation stress in both species, with a clear cross-tolerance (enhanced performance) in N. baeticus. In contrast, general negative effects on performance were found under the inverse stress sequence. The rapid and slow dehydration produced different water loss and haemolymph osmolality dynamics that were reflected in different survival patterns. Our finding of cross-tolerance to salinity and desiccation in ecologically similar species from distant lineages, together with parallel responses between salinity and thermal stress previously found in several aquatic taxa, highlights the central role of adaption to salinity and co-occurring stressors in arid inland waters, having important implications for the species' persistence under climate change.

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Desiccation resistance and water balance in southern African keratin beetles (Coleoptera, Trogidae): the influence of body size and habitat

Cited by 67 publications

References 31 publications

Discontinuous gas exchange and the significance of respiratory water loss in scarabaeine beetles

Discontinuous gas exchange and the significance of respiratory water loss in scarabaeine beetles

Water loss of male and female Alphitobius diaperinus (Coleoptera: Tenebrionidae) maintained under dry conditions

Aquatic insects in a multistress environment: cross-tolerance to salinity and desiccation

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