1990年人工释放中华卵索线虫防治麦田一代粘虫试验

在1988年释放试验基础上,1990年5月,在土中中华卵索线虫成虫密度为14.7条/m~3,粘虫密度为45头/m~2的情况下,按益害比100:1释放线虫感染期幼虫于144m~2麦田中,防冶一代粘虫幼虫。24小时后即获寄生率高峰76％,校正寄生率为52％。麦收后挖方调查,释放区土中寄生线虫密度比释放前增加2.7倍。试验表明在田间寄生线虫成虫基数为10～20条/m~3的地区,按益害比100:1释放线虫,释放前后浇水,保持土壤湿度,创造良好寄生条件,既可在当年有效地减轻粘虫为害,又可较快地提高土中寄生线虫密度,提高今后常年自然控制粘虫的能力。

RELEASE OF THE INFECTIVE JUVENILES OF OVOMERMIS SINENSIS [NEMATODA: MERMITHIDAE] TO CONTROL ARMYWORM, MYTHIMNA SEPARATA [LEP.: NOCTUIDAE] IN WHEAT FIELD IN 1990

During May of 1990, infective juveniles of Ovomermis sincnsis were released into the wheat field of Zhumadian Prefecture, Henan Province for the control of the first generation armyworm, Mythimna separata. The pre-release soil sampling indicated a population density of 14.7 adults per cubic meter for the naturally occurring O. sinensis, and 45 larvae per cubic meter for the armyworm. Approximately 648,000 infective juveniles were released into a field plot of 144 square meters at a nematode:armyworm ratio of 100:1. The corrected parasitization rate of the armyworm by the nemaatode was 52% 24 hr after the release. After wheat harvest in June, the nematode population density in the plot was found to be 54 adults and 4th instar juveniles/m3, which is a 2.7 fold increase compared to that before the release. The results suggested that when the natural population density of the mermithid is around 10-20 adults/m3 in May, releasing the mermithid juveniles at a ratio of 100 nematode to 1 armyworm along with proper irrigation before and after release to keep adequate soil humidity can effectively reduce the armyworm injury for the year. Such releases may also effectively enhance the natural control effect of the mermithid to armyworm for the following year, as a result of the increase of the mermithid population in the soil.