Evidence of high tolerance to shortterm freezing in overwintering mosquitoes Culex territans Walker (Diptera, Culicidae)

Abstract

Previously, other authors recognized that Culex territans Walker females are active at relatively low temperatures after overwintering and able to complete their first gonotrophic cycle at temperatures close to +4 °C. The present study revealed relatively high tolerance of diapausing Cx. territans females, collected from near-entrance parts of caves, to short-term freezing (20-30 min at -9…-11 °C). In experiment, the proportion of alive individuals among Cx. territans after short-term freezing was higher than that among Cx. pipiens/torrentium collected simultaneously with Cx. territans from the same hibernacula. The significant difference is revealed when Cx. territans is compared with Cx. pipiens L. only, but is not revealed in comparison of Cx. territans with Cx. torrentium Martini (although the proportions of alive individuals among Cx. pipiens and Cx. torrentium were similar). Therefore, we obtained the direct support of the hypothesis that female imagines of Cx. territans are adapted to low temperatures. Obviously, there are special physiological mechanisms in overwintering Cx . territans females underlying their tolerance to short-term freezing.