Effect of Simulated Seasonal Thermal Conditions on Hatching of Eggs of a Univoltine Mosquito1

Abstract

Aedes stimulans (Walker) is a univoltine species that ranges through continental deciduous forests of North America above 40°N. Lat. It spends the summer, fall, and winter as eggs on soil beneath the detritus layer in woodland depressions likely to be flooded by melting snow and ice in the spring. Eggs experience temperatures of 20—25 °C during incubation and the remainder of the summer. Thereafter they are subject to cold (4°C or below) for intervals up to 6 months in the field. They hatch when the ice melts during the spring thaw and water temperatures rise to 4°C or above. In the normal course of events, all eggs hatch at this time so that one generation develops annually. Under unusual conditions, when oviposition sites remain dry, hatching may be delayed for 2 years. Rarely would eggs survive because of predation, burial or premature hatching (Horsfall et al. 1973).