Effect of dietary regime and stressful temperatures on Morimus funereus larval metabolism

The effects of high and low constant temperatures on the survival and certain metabolic changes in the 7-day exposed larvae of Morimus funereus, dependent on dietary regime, have been studied. In the larvae fed the natural diet (ND), midgut protease activity dropped down to a lower level at all the temperatures investigated, whereas only at the temperature of 23°C in the larvae fed the artificial diet (AD), did midgut protease activity decrease, and this was nearly identical to that in the larvae fed the natural diet. Midgut amylase activity in the larvae fed the natural diet was nearly the same as that in the larvae from a natural habitat (NC), except at the temperature of 13°C, when it increased. In the larvae fed the artificial diet, midgut amylase activity significantly decreased at all the temperatures investigated when compared with that of the larvae from a natural habitat. Maximal increase in the fat body glycogen concentration was observed in the larvae on both diets at the temperature of 13°C. In the larvae fed the artificial diet, haemolymph trehalose concentration significantly increased at the temperature of 3°C and decreased linearly with the temperature rise of 13 and 23°C, respectively; the natural diet did not affect trehalose concentration at any temperature regime.