条纹小斑蛾的生物学特性

条纹小斑蛾Thyrassia penangae(Moor)是乌蔹莓(Japanese cayratia)的重要害虫,在南昌1年发生4～5代,以老熟幼虫结茧越冬。由于该虫各世代总有极少部分个体进入滞育,少数进入越夏的个体1年只发生2代或3代。羽化时间多出现在上午7～10时,羽化后当日或次日下午交配,交配时间集中在下午3～6时,交配一般可持续12个h左右。成虫羽化后需取食花蜜做补充营养才能充分产卵。产配后次日即可产卵。第1代成虫常将卵数十粒聚产于幼嫩叶片的背面,以后各代主要聚产于花蕾上,平均每雌产卵量为43粒。幼虫为4龄。第1代主要取食叶芽、幼枝及嫩叶,以后各代主要取食花蕾。在自然条件下各虫态发育历期:卵为4～7d;幼虫为10～14d;非滞育的茧期(指幼虫结茧后的预蛹至成虫羽化的日期)为8～11d,越夏茧期为32～40d,越冬茧期为205～224d。成虫寿命为3～13d。

Biological characteristics in Thyrassia penangae

Thyrassia penangae （Moor） a serious pest of Japanese cayratia herb （ Cayratia japonica ）. It generally occurred 4 - 5 generations each year in Nanchang, hibernating as prepupae in cocoons. There were always some individuals entering diapause in each generation. Thus, some individuals with a summer diapause only produce two or three generations each year. The overwintering individuals emerged from cocoons from early May to late May. Females need to feed on nectar before laying eggs. Females laid 10 to 20 eggs each cluster at the back of the young tender leaves in the first generation and mainly on squares in the other generations. The mean fecundity per female was 43 eggs. Larvae mainly feed on leafbuds, tender growing terminals or young leaves in the first generation and squares in other generations. There were four larval instars. Under natural conditions, developmental duration was 4 - 7 days in egg stage, 10 - 14 days in larval stage, and 8 - 12 days in pupal stage. Non-dipause cocoons had 8 - 11 days of life span （ the duration from prepupa to adult emergence）. The life span of aestivating and hibernating cocoons ranged from 32 to 40 days and 205 to 224 days, respectively. Longevity of adults ranged from 3 - 13 days.