瘦怒茧蜂的发育与生殖及对草地螟的控制作用

Developmental and Reproductive Aspects of Parasitoid Wasp, Orgilus ischnus and Its Bio-control Potentials to Loxostege sticticalis

瘦怒茧蜂Orgilus ischnus Marshall是草地螟Loxostege sticticalis L.初龄幼虫寄生蜂。为探究它的生物学特性及其对草地螟的控害作用,本文在23℃、16L：8D光周期条件下,以1龄草地螟幼虫为寄主,测定了瘦怒茧蜂的发育历期和茧重、成虫生殖行为特征、能力和寿命,研究了瘦怒茧蜂对草地螟幼虫的功能反应和寄生率,探究了寄主幼虫的取食量及虫体大小与正常幼虫的差异。结果表明,瘦怒茧蜂卵和幼虫期为12.8 d,预蛹和蛹期10.5 d,世代历期23.2 d,平均茧重为4.1 mg。成蜂羽化当天即可交配产卵寄生,属卵育型,平均交配时间为49 s,雌蜂平均产卵量为100.5粒,产卵高峰期分别为交配后第4 d和第8 d,雌、雄蜂寿命分别为11和14 d。在5~40头/瓶（650 m L）8个密度条件下,瘦怒茧蜂的寄生量随草地螟幼虫密度的增加而增加,当密度≥15头/瓶时,寄生率会随幼虫密度的增加而减小,功能反应属HollingⅡ型;寄主幼虫一生取食量为106.7 mg,仅为正常幼虫的21.3%,寄主幼虫第6和12 d的体重、大小均极显著低于正常幼虫。本文研究结果明确了瘦怒茧蜂基本的生物学特性,证明该蜂对草地螟控害作用显著,为改善、提高草地螟的可持续控制技术提供技术支撑。

Orgilus ischnus Marshall （Hymenoptera： Brachonidae） is a parasitoid of early instar larval of beet webworm, Loxostege sticticalis L.. To explore the biological characteristics and bio-control potentials of O. ischnus, the developmental duration, cocoon weight, reproductive behavior and potential, and longevity of O. ischnus were investigated using the 1st instar larval L. sticticalis as host under laboratory conditions （23 ℃, 16L： 8D）. The functional response and parasitism rate of the O. ischnus were analyzed at 8 densities from 5 to 40 host larvae per 650 mL/jar. The weight of the food consumed by the host larvae, the body weight and the size of the host larvae were compared with the un-parasitized ones. The results showed that the developmental period of egg and larvae, pre-pupae and pupae, and whole generation of the wasp was 12.8, 10.5 and 23.2 days, respectively. The cocoon average weight of the wasp was 4.1 mg. The wasp was a kind of synovigeny parasitoid, could mate immediately after emergence and oviposite soon after mating. The mating time was 49 s in average. The ovipositing peak happened at the first 4 days and the eighth day in the wasp life. The egg laying number per female in whole lifetime was about 100.5 in average. The longevity of female and male wasps was 11 and 14 days, respectively. The number of the host parasitized by O. ischnus increased as the host density increased while the actual parasitic rate decreased with the increase of host density, which fitted with Holling type II. The weight of the food consumed by the parasitized larva was 106.7 mg, only accounting for 21.3% of the normal larvae. The body weight and size of the parasitized larva were significantly less than that of the normal larva at the 6th and 12th day after parasitizing. This review makes clear the biological characteristics of O. ischnus, and demonstrates the wasp is an effective parasitoid of early stages of larval L. sticticalis, provides technical support to improve the sustainable controlling of L. sticticalis.