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

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 F1 and F2 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.