摘要
研究了菜蛾绒茧蜂对小菜蛾各龄幼虫的选择性，结果表明，菜蛾绒茧蜂能寄生小菜蛾各个龄期的幼虫，但当２，３，４龄幼虫同时存在时，该蜂偏爱寄生２，３龄幼虫，对２，３，４龄幼虫的选择系数分别为０．３７，０．３９和０．２４．菜蛾绒茧蜂对２５℃下发育的不同日龄４龄幼虫的寄生能力随寄主日龄增大而急剧下降，产卵寄生的雌蜂比例也随４龄幼虫日龄增大而急剧下降．对进入４龄并发育至该龄期３７％时间以上的幼虫该蜂不能寄生．菜蛾绒茧蜂在寄主体内的发育速率及个体大小与寄主龄期大小有关，寄生于４龄幼虫体内的发育最快、个体最大，３龄的次之，２龄的发育最慢、个体最小．试验还表明菜蛾绒茧蜂对小菜蛾幼虫的控制作用除成功的寄生致死外，还包括因不成功的产卵穿刺攻击所导致的死亡．文中还对田间该蜂寄生率估计方法进行了讨论．
The preference and suitability of Cotesia plutellae Kurdj to various instars and four different developmental ages (0-05 day old, 0-10 day old, 1-2 day old and over 2 days old at 25 ℃ respectively) in the 4th instars of diamondback moth (DBM), Plutella xylostella, were studied at 25 ℃ in the laboratory The results showed that C plutellae parasitized all 4 instars of DBM, but it preferred to parasitize the 2nd and 3rd instars when it was exposed to the 2nd, 3rd and 4th instar DBM larvae concurrently The preference indexes to the 2nd, 3rd and 4th instar were 037, 039 and 024 respectively Parasitism and the percentage of females which parasitized at least one DBM larva decreased sharply with the increase of host age in the 4th instar, and females failed to parasitize any larvae which had completed 37% of their development in that instar The development time and the final adult size of the parasites varied with the host instars at initial parasitization The parasites starting their initial parasitization in the 4th instar host had the shortest development time from egg to cocoon formation and the longest body size, followed by those in the third instar host, and then by those in the second instar The results also suggest that control efficacy of the parasite included both successful parasitism and deaths caused by the parasite's repeated, unsuccessful attacks Methods for more accurate estimation of parasitism in the field by this parasite were also discussed
基金
澳大利亚国际农业研究中心资助
关键词
菜蛾绒茧蜂
小菜蛾
龄期选择性
寄主适合性
Cotesia plutellae Kurdj
Plutella xylostella L.
host age preference
host suitability
