The relationship of egg size and incubation temperature to embryonic development time in univoltine and multivoltine aquatic insects

1. We used published data to investigate the combined influence of egg size and incubation temperature on embryonic development time for a broad assortment of aquatic insects at four different incubation temperatures (10, 15, 20 and 25 degrees C). 2. Embryonic development time (EDT) was positively correlated with egg size at each of the four temperatures, but with different relationships for univoltine and multivoltine aquatic insects. The relationships of embryonic development time to egg size expressed in degree-days did not significantly differ in slope (P > 0.50) or intercept (P > 0.05) for either univoltine or multivoltine aquatic insects at each of the four temperatures. 3. The relationship of embryonic development time (degree-days) to egg mass in multivoltine aquatic insects (EDT = 885 x(0.19), P<0.0001, r(2) = 0.48) is similar in slope and intercept to that for other oviparous animals (i.e., zooplankton, fish, amphibians and reptiles), and to the relationship of embryonic development time to neonate mass in mammals. Univoltine species on average require 3-5 times longer to develop (EDT = 14190 x(0.29), P<0.001, r(2) = 0.29) than most other animals of equivalent egg mass, but the relationship of embryonic development time to egg mass is similar in slope to that of most other animals. Together, these relationships provide a basis for evaluating differences in embryonic development time among aquatic insects.