斯氏线虫对两种地老虎的侵染效果

１９９１￣１９９３年室内试验结果证明：芜菁夜蛾线虫的３个品系Ｂｅｉｊｉｎｇ、Ｍｅｘｃｉａｎ、Ｏｔｉｏ对八字地老虎和小地老虎两种地下害虫的幼虫有很高的侵染力．用Ｂｅｉｊｉｎｇ品系线虫处理八字地老虎３龄幼虫，幼虫死亡率随线虫剂量而增加，当剂量为８０条线虫／八字地老虎幼虫时．死亡率可达９３％以上．每头３龄小地老虎幼虫用８０条该线虫处理的死亡率为８０％，用同一剂量的Ｍｅｘｉｃａｎ品系，八字地老虎和小地老虎的死亡率分别为８６．６％和８５．１％．Ｏｔｉｏ品系对两种幼虫的致死率达７０％￣８３．３％．ＮＣ３２品系对八字老虎毒力较差．即使剂量增至１６００条线虫／虫，八字地老虎的死亡率仅为４０％，表明不同品系线虫对害虫毒力差异较大．

EFFECT OF STEINERNEMATID NEMATODES AGAINST TWO CUT WORMS AMATHES C-NIGRUM AND AGROTIS YPSILON(LEPDOPTERA: NUCTUIDAE)

Effect of the entomopathogenic nematodes Steinernsma feltiae and S.bibionis for the control of two cut worms, Amathes c-nigrum and Agrotis ypsilon,on soybean was evaluated under laboratory conditions.When 20,40,80 or 160 nematodes of S. feltiae Beijing per cut worm larva of A.c-nigrum we:pipetted in lmL of water on to moistened filter paper in petri dishes containing 5 three-instar larvae, average larval mortality was 71.8, 78.6, 85.3 and 93.6%, respectively, after 7d of incubation at 25℃. In a comparison of three Strains (Beijing, Mexican and Otio) applied at 80 nematodes per larva, strain Beijing was more effective than two other stains. Maximum mortality caused by the Mexicam and Otio strains of S. bitionis was only 80.3 and 86.7% respectively. When S. feltiae Beijing was mixed with a 5cm layer of soil at a rate equivalent to 2.5, 5.0, 10.0, 20.0, or 40.0×109/hm2 62.5, 75.0, 80.0, 100.0 and 100.0%, respectively,of 40 cut worm larvae added were killed after incubation for 3 days at 25℃. However,only 40.0% of the cut worm was killed by S.glaseri NC32 at the rate of 40.0×109/hm2 The maximum larval correct mortality of A.ypsilon was 68.9,79.3 and 86.1Caused by the Otio, Beijing and Mexican strains, respectively, at the rage of 80 nematodes per larva. That showed S.feltiae Mexican was more offective than the others. These results show that the cut worms are highly susceptible to entomopathogenic nematodes in the laboratory.