Possible role of neurohormones in the process of acclimatization and acclimation in Morimus funereus (insecta)—II. Changes in the haemolymph free amino acid content and digestive enzyme activity

Abstract

1. 1. The effect of constant temperatures (− 1, 8 and 23°C) on the haemolymph free amino acid content and on the activity of digestive enzymes (protease, amylase) in Morimus funereus larvae (b.wt 200–500 mg) in different periods of annual cycle was studied. 2. 2. In addition to stable period two critical periods during the annual cycle were differentiated. 3. 3. In the stable period temperature provokes nonspecific response of dominant and physiologically significant free amino acids (increase of proline, decrease of lysine, histidine and tyrosine). 4. 4. In the first critical period (the end of winter) at temperatures of − 1 and 23°C the total pool of free amino acids (i.e. lysine, histidine, tyrosine) is increased and proline is decreased, while at 8°C no significant changes were observed. 5. 5. The proteolytic activity shows an abrupt decrease, whereas amylolytic activity exhibits temperature selective increase. 6. 6. In the second critical period (the end of summer) no significant changes in the total pool of free amino acids and proteolytic activity were observed except at 23°C when a decrease of both parameters was evident. 7. 7. The amylolytic activity shows a slight decrease at all temperatures studied. 8. 8. The results are discussed from the aspect of the role of neurohormone(s) in the processes of acclimatization, acclimation and stress.