芜菁夜蛾线虫对沟眶象和臭椿沟眶象侵染力的研究

室内应用斯氏线虫3个种的5个品系,对越冬沟眶象幼虫进行侵染力比较,结果表明,施线虫后8天,芜菁夜蛾线虫A24品系和Beijing品系,可使在土壤内的幼虫死亡率分别达100％和90％,14天后Beijing品系的致死率亦达100％,其它3个品系均达90％左右;在土壤含水量为10～20％范围内,幼虫死亡率随土壤含水量的增加而递增,施线虫后5天,含水量20％的处理,幼虫死亡率达70％,而10～15％含水量中,死亡率为45～50％;线虫对沟眶象成虫的致死率很低仅15％。对为害臭椿树的沟眶象幼虫,用A24和Beijing品系进行防治,效果分别为77.3％和70.0％。

CONTROL OF WEEVILS DAMAGING AILANTHUS TREES IN BEIJING WITH STEINERNEMATID NEMATODES

Laboratory tests were conducted in Beijing on the infectivity of 3 species and 5 strains of the entomopathogenic nematode, Steinernema spp. on the overwintering larvae of Eucryptorrhynchus chlnensis Col.: Curculionidae], a pest of the important ornamental tree, Ailanthus altissima. Two Chinese strains of S.feltiae, strains A24 and Beijing, caused 100% and 90% mortalities of the larvae 8 days after the treatment. The larval mortality for Beijing Strain reached 100% by the 14th day after the treatment. Mortalities of the larvae infected with the other 3 strains tested were all about 90%. The results also showed that the larval mortality increased as the soil water content increased in the range of 10-20%. On the 5th day of the treatment, the larval mortality was 70% in the soil of 20% water content. The mortality was 45-50% when the soil water content was 10-15%. Infection of the weevil adults caused only 15% mortality. In a field trial of controlling E. chinensis and another weevil, E. brandti, infesting the Ailanthus trees in the suburbs of Beijing, the A24 and Beijing strains gave control effects of 77.3% and 70.0%, respectively.