Studies on the Egg Diapause and Overwintering of Aedes albopictus in Nagasaki

ヒトスジシマカの休眠卵は低温短日下で育った雌成虫によって産まれるが,卵休眠を誘起する温度,日長条件に最も感受性が高いのは蛹と成虫期であった.長崎では9月中旬から休眠卵が多くなり,10月下旬には産まれる卵がすべて休眠卵であった.休眠卵は翌年2月頃覚醒するまでは孵化することはなく,屋外では3月中旬から5月下旬にかけて孵化する.しかし,非休眠卵でもある程度の耐寒性を備えており乾燥していたりすると越冬も可能である.それゆえ休眠卵は秋に卵が孵化し冬の寒さで幼虫が死滅することを防ぐのに役立っていると考えられる.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 sensitive 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