杉木半穿刺线虫病的研究 (2)生活史、自然消长及生物学

杉木半穿刺线虫病病原线虫是柑桔线虫Tylenchulus semiPenetrans).在福建一年发生10～12代,以卵囊和二龄幼虫在根部或根际土壤中越冬,二龄雌幼虫侵袭根部,完成一世代时间是3～5周。种群数量自然消长与土温有关,而主要与杉木根萌发期一致。虫口密度一年内出现两个高峰期,阳坡比阴坡高,随林龄增大而递增。线虫在土壤中垂直分布深度达1.2m,而虫口密度最大是分布20～60cm土层。卵囊的活卵率平均为85％,卵的孵化率在杉木浸汁液中是90％,在清水中是70％。在清水中从卵发育至雄成虫需46～55天,雌幼虫在根外不能发育成虫。卵的发育最高温度35℃,致死温度40℃,雌雄虫性比为56:1。

Studies on the Nematode Disease of Cunninghamia lanceolata (2) The life history and the population Change in natural Condition, and the biological characteristics

The nematode disease of Cunninghamia lanceolata was by Tylenchulus semipenetrans Cobb, 1913. The nematode has 10~12 generations a year in Sha-xian county Fujian province. The nematode overwinters with the egg-sac and the second-stage juveniles in the roots and the soil. The roots were infected by the second-stage female larve. The complete life history from egg to egg of nematode requires three five weeks. The population of nematode is largest in g -rowing root of Cunninghamia lanceolata, there aretwo infections in a year fromJannary to the first ten days of May, and from the last ten days of August to the second ten days of Nevember, the population of nematodes in the southen aspects is larger than the northen aspects, the nomatodes verticolly exist at a depth of 1.2m in soil, but largest population are at 20~60cm. The hatchaba-lity of egg is 70% in water, and 90% at immersion roots of Cunninghamia lan-ceolata. The complete life history from male larva to adult requires 46~55 days in water, but the but the female larva does not become adult female. The highest temperation for egg development is 35℃, the lethal temperation is 40℃ , female: male is 56 : 1 .