Physiological states affect metabolic response to high temperature in Morimus funereus larvae

Abstract

The metabolic response (fat body glycogen and haemolymph trehalose concentration, midgut amylolytic and proteolytic activities) of Morimus funereus to a high stressful temperature has been studied in larvae from two physiological states (0–6 hr after moulting, “non-feeding” larvae; 7 days after moulting “feeding” larvae), during the intermoult period. The results obtained reveal differences in the response of the larvae from each group to a constant temperature of 35°C. These differences are most prominent for fat body glycogen and midgut protease activity. Glycogen concentration in the fat body and midgut protease activity increase significantly in “non-feeding” larvae at the beginning of exposure of the larvae to 35°C. At the end of the experimentally induced stress, the glycogen concentration was significantly above the control value, while midgut protease activity was close to that of the control. In the “feeding” larvae, glycogen was nearly exhausted on the fourth day of exposure, while proteolytic activity decreased below the control level. During thermal stress, various types of metabolic responses dependent on physiological states were observed at the level of the metabolic parameters studied.