The negative effect of starvation and the positive effect of mild thermal stress on thermal tolerance of the red flour beetle, Tribolium castaneum

Abstract

The thermal tolerance of a terrestrial insect species can vary as a result of differences in population origin, developmental stage, age, and sex, as well as via phenotypic plasticity induced in response to changes in the abiotic environment. Here, we studied the effects of both starvation and mild cold and heat shocks on the thermal tolerance of the red flour beetle, Tribolium castaneum. Starvation led to impaired cold tolerance, measured as chill coma recovery time, and this effect, which was stronger in males than females, persisted for longer than 2 days but less than 7 days. Heat tolerance, measured as heat knockdown time, was not affected by starvation. Our results highlight the difficulty faced by insects when encountering multiple stressors simultaneously and indicate physiological trade-offs. Both mild cold and heat shocks led to improved heat tolerance in both sexes. It could be that both mild shocks lead to the expression of heat shock proteins, enhancing heat tolerance in the short run. Cold tolerance was not affected by previous mild cold shock, suggesting that such a cold shock, as a single event, causes little stress and hence elicits only weak physiological reaction. However, previous mild heat stress led to improved cold tolerance but only in males. Our results point to both hardening and cross-tolerance between cold and heat shocks.

Effects of Thermal Regimes, Starvation and Age on Heat Tolerance of the Parthenium Beetle Zygogramma bicolorata (Coleoptera: Chrysomelidae) following Dynamic and Static Protocols

“…such that a pre-exposure to heat may also improve cold tolerance or vice versa [9,21,22]. Furthermore, exposure to stressors other than temperature such as starvation, desiccation and hypoxia may also affect thermal tolerance [23–27]. For example, starvation reduced cold tolerance in Tribolium castaneum (Coleoptera: Tenebrionidae) whilst heat tolerance remained unaffected [27].…”

“…Furthermore, exposure to stressors other than temperature such as starvation, desiccation and hypoxia may also affect thermal tolerance [23–27]. For example, starvation reduced cold tolerance in Tribolium castaneum (Coleoptera: Tenebrionidae) whilst heat tolerance remained unaffected [27]. In contrast, feeding in locusts Locusta migratoria (Orthoptera: Acrididae) resulted in poor cold tolerance [28].…”

Context‐dependent effects of cold stress on behavioral, physiological, and life‐history traits of the red flour beetle

“…The improvement was stronger for females than males. The effect of several cold shock events found here resembles the effect of a longer exposure to a higher temperature (but still lower than the growth temperature), resulting in a faster recovery from chill coma, but more so for females than for males (Scharf et al ., ). Clearly, our design cannot totally separate between the effect of repeated cold shock and that of longer cold exposure (Marshall & Sinclair, ).…”

“…We created each generation by mating 80–100 adults in each of 3 boxes, letting them lay eggs for 3–4 d, after which they were removed. The 3 lines were crossed every 4–5 generations to reduce the loss of genetic diversity (Scharf et al ., ). Larvae were grown in ∼120 g flour‐yeast mixture (ratio of 10 : 1) and pupated after less than 3 weeks.…”

“…Although occurring mostly in storage mills, it experiences significant thermal fluctuations (Campbell et al ., ). Thermal tolerance of the red flour beetle is affected by a short‐term acclimation of a few days, temperature during development, recent feeding, and age (Halle et al ., ; Scharf et al ., , ). This species is a strong disperser (Ziegler, ; Romero et al ., ), whose promiscuous mating system involves both sexes mating numerous times throughout life, with females continually laying eggs (Fedina & Lewis, ).…”