Feeding behaviour, digestive physiology and lipid content in macropterous females of Pyrrhocoris apterus (L.) (Heteroptera: Pyrrhocoridae)

Abstract

Abstract. Macropterous females of Pyrrhocoris apterus (L.) reared under short‐day conditions (LD 12:12 h) were analysed for temporal patterns of feeding and drinking behaviour, activities of digestive enzymes in the gut, and lipid and glycogen content in the haemolymph and fat body. Peaks of drinking activity were recorded at days 3, 7 and 10 during the first 14 days after imaginal ecdysis. Feeding activity peaked on the third day, ceasing completely after the fourth day of adult life. Esterase, protease, amylase and aminopeptidase activities exhibited the highest overall activity in the first days after imaginal emergence; then enzyme activities decreased. In the fat body, the content of lipids was highest on day 5, then a decrease of about 40% was observed at day 14; the amount of glycogen was highest on day 1 at 11 μg of glucose equivalents/mg of fat body, then decreased to 2 μg at day 14 after the imaginal moult. In the haemolymph, the lipid content rose until day 8 when it reached almost 0.3 μmol/μl; at day 14 the value was slightly lower. The association of fasting with reproductive arrest in macropterous females of P. apterus, accompanied by a decrease in digestive enzyme activities and a mobilization of lipid reserves from the fat body, was demonstrated.