Comparative study of the metabolic responses during food shortage and subsequent recovery at different temperatures in the adult lesser mealworm, Alphitobius diaperinus (Coleoptera: Tenebrionidae)

Abstract

Metabolic responses to prolonged food shortage (35 days) and subsequent re-feeding (14 days) were investigated in adults of an introduced beetle, Alphitobius diaperinus Panzer, as a function of temperature (12, 16, 20 and 24°C). Various qualitative and quantitative changes that greatly vary according to the temperature experienced occurred in metabolite levels during prolonged starvation. Whereas levels of protein and ATP did not change significantly, triglycerides decreased markedly and glycogen changed little. Metabolite levels were differently affected by temperature, with triglycerides being less rapidly degraded at 20 than at 24°C and almost completely depleted at 12 and 16°C; in contrast to higher temperatures, glycerol is accumulated at 12°C. Physiological adaptation to starvation and low temperatures are highly linked and energy allocation for starvation vs. temperature acclimation must be strictly regulated, both being essential for insect survival. Re-synthesis rates during recovery are probably highly temperature-dependent for all metabolites. The proteins retained during starvation and the preferential degradation of lipids allowed a rapid recovery. Above 16°C, adult A. diaperinus regained locomotory activity rapidly and the triglyceride, glycerol and glycogen reserves were restored. This tropical species may be able to colonize other environments such as natural and/or artificial biotopes where conditions are close to those of its natural habitat.