Sex ratios at emergence in populations of some central European Gomphidae species (Anisoptera)

At emergence (F-0) a significant bias for 9 9 was observed within the Moravian (Czech Republic) populations of Gomphus flavipes (Charp.), G. vulgatissimus (L.) and Ophiogomphus cecilia (Fourcroy). <J 6 represented 45.6% of all specimens (43.5% in the first and 46.4% in the second research year). The results of the x2 test supported the 9 -biased sex ratio in populations of all 3 spp. The sex ratio in populations varied significantly in time during the emergence season, caused by the fact that all 3 spp. demonstrated a significant protandric trend. The greatest changes in sex ratio during the emergence season were demonstrated by G. flavipes (coefficient value -0.007542); the smallest were recorded in G. vulgatissimus (CV -0.008617). Environmental impact did not prove to act be a factor which has an effect on the sex ratio of species with phenotypical determination of sex.