蝶蛹金小蜂在杭州的年生活史

蝶蛹金小蜂是菜粉蝶蛹期的主要寄生蜂。在杭州,绝大多数以老熟幼虫在寄主蛹内越冬。田间养虫室内饲养结果:1979年发生11—12代;1981年早、中、迟三组分别为12—13代、10—11代以及9—10代,三组合计,非越冬代成虫自5月上旬至12月初始终不断,一年之内,前后(连续或不连续)两代成虫重叠发生的天数至少175天,前后(连续或不连续)三代成虫重叠发生的天数至少49天。 2、3月间小蜂即可羽化,远远早于田阔第一代菜粉蝶蛹的出现,惟不能寄生越冬后的越冬代菜粉蝶蛹,但越冬代蜂的羽化盛期仍处于田间第一代菜粉蝶蛹初见至化蛹始盛期之间,且喂食后寿命很长,故越冬代蜂与第一代菜粉蝶蛹之间的发生期基本上是吻合的。其后,两者代数既多(菜粉蝶一年发生9代),发生又都不整齐,小蜂成虫与菜粉蝶蛹均连绵不断,时间上彼此也是吻合的。这是此蜂自然寄生率高并成为其重要天敌的一个主要原因。 对发生代数多、世代重叠的重要天敌建议分期分批饲养,以深入掌握其生活史及与寄主发生的关系。

LIFE HISTORY AND OCCURRENCE OF PTEROMALUS PUPARUM L. IN HANGZHOU

Pteromalus puparum L. is the principal pupal parasite of the small white butterfly Ar-togeia rapae (L.) in most parts of China. In Hangzhou it overwinters mostly as mature larva in the host pupa and can breed up to thirteen generations a year. The adults of non-overwintering generations occur successively from the beginning of May to the beginning of December. The adults from the overwintered larvae may emerge in February and March and the time of their emergence is much earlier than the occurrtnce of the first generation host pupae in the field. They cannot parasitize the overwintered host pupae in the spring, but most of the overwintering parasites emerge during the period from the time when the first rupa of the first Host generation appears fill about 20% of the first generation host larvae pupate. They can live longer than one month when feeding on 20% honey, Therefore, the overwintering generation adults of P. puparum and the first generation host pupae are basically synchronized. Since then both of them enter into the overlapping generations in the year and the ovipositing parasites have ample opportunity of find the host pupae. They are synchronized and this is one of the reasons why P. puparum becomes the principal parasite of the small white butterfly with high rate of parasitization.It is suggested that the principal parasite which has many generations in the year should be bred separately according to the period of its emergence and oviposition to elucidate the number of generations it can occur in the year and the status of its synchronization with the host.