中华卵索线虫Ovomermis sinensis对蔬菜害虫的人工感染和菜田释放试验

1996—1997年,在福州,用中华卵索线虫Ovomermis sinensis(Chen et al)侵染期幼虫对当地主要蔬菜害虫,菜青虫、斜纹夜蛾和甜菜夜蛾等幼虫,在室内做人工感染试验。在室温20—28℃,寄生线虫与宿主昆虫的比例为为80:1的情况下,线虫对菜青虫、斜纹夜蛾和甜菜夜蛾幼虫的寄生率分别为50％,94％,92％。在当地土壤中无中华卵索线虫的空心菜田,设三个小区,每小区15m~2,各移植斜纹夜蛾2—3龄幼虫150头于菜株上,A区用12540条线虫侵染期幼虫混在2460克湿沙中,撤施于植株根部土面;B区用同样数量的线虫混在8公斤水中,喷洒在菜株上;C区为不释放线虫的对照区。于释放线虫后的第4天和第7天,从各小区随机回收斜纹夜蛾幼虫20头和30头,在室内单头饲养,检查线虫的寄生率和寄生强度。结果:第4天调查寄生效果相近,寄生率分别为61.1％,60％。第7天调查寄生率分别为76.7％,70％。而对照区的虫体中均未见有线虫寄生,寄生率为0。差别显著。在元白菜上释放中华卵索线虫侵染期幼虫,莱青虫的寄生率为6.6％。

ARTIFICIAL INFECTIONS AND RELEASE OF Ovomermis sinensis TO VEGETABLE INSECT PESTS

In laboratory experiments carried out in 1996 ?1997 in Fujian Province, the local major vegetable insect pests, such as Pieris rapae (Linnaeus) Spodoptera litura (Fabricius) and Spodoptera exigua (Hubner) , were infected by the juveniles of O. sinensis. The parasitic rates of O. sinensis in P. rapae, S. litura and S. exigua were 50% , 94% and 92% , respectively, at room temperature of 20?28(?) C and the ratio of 80:1 between the parasitic nematodes and the host in-sects. In the local vegetable field grown with water convolvurnlus where the soil without O. sinen-sis, three plots were designed and each one was 15m2. In each plot, one hundred and fifty 2?3 instar larva of S. litura were transferred onto the surface of vegetables. In the plot A, 2460g wet sand mixed with 12540 infective juveniles of O. sinensis was spread on surface of the soil around the plant roots. In the plot B, 8kg of water mixed with the same number of infective juveniles of O. sinensis was sprayed on the plants. Plot C was used as control. At 4th and 7th day after re-leasing of O. sinensis, 20 and 30 larvae of 5. litura were collected from each plot and the individual larva was reared separately in laboratory and the parasitic rate and parasitic intensity were deter-mined. The results showed that the parasitic effect at 4th day was similar and the parasitic rates were 61. 1% and 60. 0% , respectively. The parasitic rates at 7th day were 76. 7% and 70. 0% , respectively. No parasitic nematode was found in lava's body of insect in the control plot C and the parasitic rate zero. The difference was significant. The parasitic rate of infective juveniles of ?O. sinensis was 6. 6% in P. rapaee when they were released on cabbage (Brassica caulorapa Pasq. ).