Temperature dependent embryogenesis in Aeshna tuberculifera Walker and Plathemis lydia (Drury) under field and laboratory conditions (Anisoptera: Aeshnidae, Libellulidae)

Hatching success and rate of embryonic development were measured at 7 constant temperatures in the laboratory and in 5 natural ponds in western Virginia, USA. Hatching success in the lab was reduced at low temperatures for P. lydia and at high temperatures for A. tuberculifera. These results are consistent with the phenologies and geographical distributions of these spp. Hyperbolic functions accurately described the affects of temperature on the logarithmic rate of embryogenesis for both spp. in the laboratory but temperature appeared to have little influence on either hatching success or embryogenic rate in the field. Thus other environmental factors must have accounted for the variation which existed among ponds in both hatching success and rate of embryonic development. Circumstantial evidence suggests that oxygen level may have been the important limiting factor in the ponds investigated in this study.