Cold acclimation conditions constrain plastic responses for resistance to cold and starvation in Drosophila immigrans

Abstract

In montane Drosophila species, cold-induced plastic changes in energy metabolites are likely developed to cope with cold and starvation stress. Adult Drosophila immigrans reared at 15°C were acclimated at 0°C or 7°C for durations of up to 6 days (fed or unfed conditions). Such flies were tested for plastic changes in resistance to cold or starvation stress as well as for possible accumulation and utilization of four energy metabolites (body lipids, proline, trehalose and glycogen). Adults acclimated at 7°C revealed a greater increase in cold tolerance than flies acclimated at 0°C. Different durations of cold acclimation at 7°C led to increased level of body lipids only in fed flies which were utilized under starvation stress. However, such plastic responses were not observed in the flies acclimated at 0°C, which remained unfed due to chill-coma. These observations suggest a possible role of feeding to improve starvation resistance only in the flies acclimated at 7°C with food. Cold acclimated D. immigrans flies revealed improved cold resistance through a possible reshuffling of trehalose and glycogen; and starvation-induced proline which was utilized under cold stress durations. Finally, greater reduction in mean daily fecundity due to cold or starvation was observed in 0°C acclimated flies as compared to 7°C acclimated flies. Thus, cold acclimation conditions (0°C or 7°C) greatly impact resistance to cold and starvation in D. immigrans.

Effect of starvation on the cold tolerance of adult Drosophila suzukii (Diptera: Drosophilidae)

“…Yet, this positive effect of short-term starvation on acute cold tolerance occurred faster in males than in females. These observations support the notion that starvation can promote cold tolerance, particularly survival-related traits (Le Bourg, 2013;Le Bourg and Massou, 2015;Pathak et al, 2018). Generally, males were more likely than females to survive acute cold exposure, albeit significant differences between both sexes were merely found after 12 and 24 h of fasting.…”

“…From our data, it was clear that flies had their physiological status and their energy stores altered by starvation, and we thus expected this pre-treatment to affect cold tolerance in some positive ways (cross-tolerance and hormesis), as reported in other Drosophila studies (e.g. Le Bourg, 2013;Le Bourg and Massou, 2015;Pathak et al, 2018). Genetic associations between resistance to cold and starvation have been investigated in laboratory-selected strains for different stressors in D. melanogaster to find cross-tolerance effects (Bubliy and Loeschcke, 2005).…”

“…Fed locusts (Locusta migratoria) had an increased CCRT compared to fasted counterparts (Andersen et al, 2013). Similarly, in a study on Drosophila immigrans, a beneficial effect of starvation on the cold tolerance was found (Pathak et al, 2018). In that study, flies that have fasted for 48 h had greater cold tolerance than their fed counterparts (differences in CCRT and survival after cold-shock), thus suggesting again a possible cross-tolerance between starvation and cold tolerance.…”

“…Food deprivation can also alter insect cold tolerance. Indeed, several studies have shown that starvation can affect the resistance to long-term cold stress in D. melanogaster (Le Bourg, 2013;Le Bourg and Massou, 2015;Pathak et al, 2018), but the underlying mechanisms remained unresolved.…”

Evaluation of the Expression and Function of the TRE2-like and TRE2 Genes in Ecdysis of Harmonia axyridis

“…When faced with various natural threats, H. axyridis adapts with different strategies, such as gathering in winter to protect against cold (Durieux et al, 2015) and releasing harmful exudates to expel natural enemies (Schmidtberg et al, 2019). As an immediate source of energy, trehalose plays a vital role in the energy storage of the H. axyridis , in the oxidative function of various physiological activities, and in the growth and development (Ge et al, 2011; Xie et al, 2013; Kojić et al, 2018; Pathak et al, 2018; Zhao et al, 2018). Trehalose is called the “blood sugar of insects” (Yu et al, 2008; Wu et al, 2019), and it is a non-reducing disaccharide composed of glucose units linked by two glycosides and is found in bacteria, yeasts, fungi, plants, insects, and other invertebrates (Elbein et al, 2003; Frison et al, 2007; Tang et al, 2008).…”