Studies on the egg diapause and overwintering of Aedes albopictus in Nagasaki

Diapausing eggs of Aedes albopictus are laid by females reared under the condition of low temperature and short photoperiod. The pupa and the adult are sen- sitive stages to temperature and photoperiod in the induction of egg diapause. In Nagasaki, diapausing eggs increase in mid September, and all eggs laid after October are in diapause. These diapausing eggs overwinter, and would not hatch until the diapause is broken in February of the next year. Hatching of diapausing eggs begins in mid March and continues until late May. Through some non-diapausing eggs can overwinter, it is sure that most overwintering eggs are in diapause in the field. It seems that the advantage of egg diapause is to prevent eggs from hatching before winter.