Department of Integrative Biology

The circadian rhythm of the release of sperm from the testes into the vasa deferentia in wild gypsy moth (Lymantria dispar) males was found to be the same as the rhythm previously observed in the laboratory strain of the same species. To determine the temporal relationship between sperm release and mating activity, daily rhythms of sperm release and mating flight were compared in two closely related species, L. dispar and L. monacha. While the peaks of sexual activity of wild males were approx. 8 h apart, the period of sperm release was essentially identical in the two species. It was concluded that the phase of sperm release is not linked to the phase of mating activity but rather, the two rhythms are independently timed.