Temporal pattern of feeding activity in the firebug Pyrrhocoris apterus and its relation to sex, wing dimorphism and physiological state of adults

Abstract

Abstract The present study tested whether the pattern of feeding activity in the firebug Pyrrhocoris apterus (L.) is sex‐ and wing morph‐related, diurnal or nocturnal, as well as whether the feeding rhythm persists in constant darkness. Temporal patterns of feeding activity are analysed in macropterous and brachypterous adults reared under long‐day (LD 18 : 6 h) and short‐day (LD 12 : 12 h) photoperiods, and in adults transferred to constant darkness. In females, the total feeding activity is highest in long‐day reproductively active brachypters, intermediate in short‐day diapausing brachypters, and lowest in macropters; the differences among males are substantially smaller. Although the total feeding activity of macropterous males is higher than in macropterous females, no sex‐related differences are found in feeding activity of diapausing and reproductively active brachypters. The frequency of feeding exhibits sex‐related differences, with obviously higher values in males. Mean feeding periods of macropterous and reproductively active brachypterous males are shorter than in females of the same wing morph. Mean interfeeding periods are longest in macropters, intermediate in diapausing brachypters, and shortest in reproductively active brachypters, and always lower in males than in females. The study shows that the feeding activity of P. apterus adults is age‐, sex‐ and wing morph‐related, and exhibits a diurnal pattern, except in reproductively active brachypterous females. The latter do not express a clear diurnal rhythm of feeding, presumably because of interactions with cycles of egg development and oviposition. The persistence of diurnal rhythm of feeding activity in short‐day brachypterous females transferred to constant darkness indicates an endogeneity of this rhythm in P. apterus.