温度对绿眼赛茧蜂寄生率及生长发育的影响

绿眼赛茧蜂Zele chlorophthalmus(Spinola)是草地螟Loxostege sticticalis L.幼虫的重要寄生蜂。但目前国内外对其生物学特性及其发生与温度的关系还没有报道。为了阐明绿眼赛茧蜂的生物学特性,并为其室内扩繁及田间保护利用提供试验依据,本文分别在17、21、25、29和33℃、相对湿度70%±5%、光周期16L:8D条件下,以草地螟3龄幼虫为寄主,研究了其寄生率和生长发育特征的变异,明确了其发育起点温度和有效积温,以及在我国草地螟主要发生危害区的发生为害世代。结果表明,在17~29℃,绿眼赛茧蜂能与寄主建立寄生关系,并能完成发育。其中以21和25℃的寄生率最高(67.3%和60.0%),子代结茧率和羽化率最高(70%)并显著高于29和17℃的。另外,绿眼赛茧蜂的蛹(茧)重和成虫寿命随温度的升高而下降。但在33℃,寄生率为0,不能与草地螟建立寄生关系;在17~25℃,卵-幼虫、预蛹-蛹及世代发育历期随温度的升高而缩短,但在29℃时,发育历期比25℃的有所延长。Logistic曲线和线性模型均可描述绿眼赛茧蜂发育速率与温度的关系,但前者的决定系数(R2=0.935~0.971)比后者(R2=0.859~0.890)高,因而Logistic曲线能更好地反映绿眼赛茧蜂发育速率与温度的关系;卵-幼虫、预蛹-蛹以及世代的发育起点温度依次为8.7、9.9和10.8℃,完成发育所需的有效积温分别为176.0、189.6和331.8日·度。绿眼赛茧蜂在我国草地螟发生危害区可发生2~7代/年。

Effect of Temperature on Parasitism Rate and Life History Parameters of a Solitary Endoparasitoid,Zele chlorophthalmus (Hymenoptera: Brachonidae)

Abatract:Zele chlorophthalmus (Spinola) is a solitary koinobiont endoparasitoid parasitizing the beet webworm,Loxostege sticticalis L.(Lepidoptera:Crambidae),one of the most destructive insect pests of crop and fodder plant in northern China.Variations in parasitism rate and life history parameters ofZ.chlorophthalmus were investigated at 5 constant temperatures (17,21,25,29,and 33 ℃) by using the 3rd instar L.sticticalis as host.The parasitism rates at 21 and 25 ℃ were significantly greater than those at 17 and 29 ℃,but no parasitism rate was found at 33 ℃.The pupation and emergence rates at 21 and 25 ℃ (＞70％) were all higher than those at 17 and 29 ℃.The pupal weight and adult longevity decreased with increasing temperature.Developmental duration of eggs,larvae,pre-pupae,pupae,and whole generation decreased lineally with increasing temperature within 17-25 ℃ but extended slightly at 29 ℃.The relationship between temperature and developmental rate of Z.chlorophthalmuswas better fitted by the Logistic model (R2=0.935-0.971) than linear model (R2=0.859-0.890).Threshold temperature for eggs and larvae,pre-pupae and pupae,and full generation was 8.7,9.9 and 10.8 ℃,respectively,and thermal constant was 176.0,189.6,and 331.8 day-degrees,respectively.Z.Chlorophthalmus might complete 2-7 generations annually in areas where L.sticticalis occurs and the annual number of generation appeared decreasing with increasing latitude.This data can be useful in determining the potential of using Z.Chlorophthalmus as a biological agent,by optimizing mass rearing and release techniques of the parasitoid.