Larval diapause, size, and autogeny in the mosquito <i>Aedes togoi</i> (Diptera, Culicidae) from tropical to subarctic zones

Abstract

Larval development of nine populations of Aedes togoi (Theobald) collected from tropical to subarctic zones was studied under photoperiods of 16 h light (L) : 8 h dark (D) and 10 h L : 14 h D at 15 °C. Larvae that did not pupate within 60 days were regarded as diapausing. Larval diapause did not occur in all populations at 16 h L : 8 h D. At 10 h L : 14 h D, four populations from tropical and subtropical zones included no diapausing larvae, whereas 60–99% of individuals from five northern populations of Japan and Canada were diapausing. Adult size increased with latitude of original locality. The proportion of autogenous females among those developed at 16 h L : 8 h D and 15 °C decreased with original latitude, whereas that among females from nondiapausing larvae reared at 10 h L : 14 h D and 15 °C was consistently high throughout the latitudes. At 10 h L : 14 h D and 15 °C, larval developmental characters of F 1 and F 2 hybrids between Malaysian (no diapause) and Japanese (diapausing) populations were intermediate between the parental populations. Expression of autogeny of the hybrids was similar to that of the Malaysian strain. A Canadian population, which might have been introduced from Japan, showed developmental traits similar to those of two populations from temperate Japan.