Latitudinal gradient in response of wing polymorphism to photoperiod in a flightless bug, Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae)

Abstract

The aim of this study was to determine if there is a latitudinal gradient in the photoperiodic regulation of wing dimorphism in the flightless bug, Pyrrhocoris apterus (L.). For this purpose individuals from three geographical populations (Israel, Spain and Czech Republic) were reared under different photoperiods and the wing length of the adults analyzed. The highest percentage of long-winged (macropterous) specimens was found in the population from Israel (35.3%), whereas percentages of macroptery were lower in the cultures from Spain (9.5%) and Czech Republic (8.6%). A higher proportion of macropterous specimens was recorded in the northern population of P. apterus kept under long daylengths (Czech Republic, 16 h) than in the southern populations (Spain, 14-15 h; Israel, 12 h). The results indicate that there is a latitudinal gradient in the critical photoperiod determining wing length in P. apterus.