明尼苏达被毛孢代谢物对大豆胞囊线虫二龄幼虫的影响

Effects of Hirsutella Minnesotensis Metabolites on Soybean Cyst Nematode Juvenile

明尼苏达被毛孢是大豆胞囊线虫幼虫专性寄生真菌，是一类具有潜力的线虫生防资源。为了探讨明尼苏达被毛孢对大豆胞囊线虫的生防作用机制，实验室条件下，研究了明尼苏达被毛孢1—10代谢物原液及不同稀释液对大豆胞囊线虫二龄幼虫（J2）活性的影响和J2对大豆根浸出液及大豆根的趋性。结果表明：代谢物原液及其不同稀释度可以显著抑制J2活性，24h时原液、5×、10×、20×和50×对J2致死率分别为91％、75％、50％、36％和31％，显著高于无菌水对照7．2％，且J2致死率随时间的延长而逐渐提高；J2在1．10代谢物最近处0～1cm分布率最低，表明J2对1～10代谢物存在趋避性；J2在根浸出液最近处0～1cm分布率最高，表明J2对根浸出液存在趋向性；在距处理液0～1cm，J2对根浸出液／1～10代谢物混合液趋避性仍然十分明显；大豆幼根蘸代谢物影响下J2在距豆根0～1cm分布率低于无菌水处理的幼根，且差异显著，说明1～10代谢物可以降低J2对大豆根的趋向性。

As an fungal endoparasites of soybean cyst nematodes （SCN）juvenile, Hirsutella minnesotensis was a potential biological control agent. To discuss the mechanism of Hirsutella minnesotensis on SCN, the effect of Hirsutella minnesotensis 1- 10 metabolites at the original and different dilute solution on second stage juveniles （J2）mortality and its effect on the attrac- tion of J2 to soybean root diffusate or soybean root on agar plate was investigated. It was deduced that both the original and different dilute solution of 1-10 metabolites could significantly restrain the activity of J2, and that the effect of the metabolites at the original,5,10,20 and 50 on the mortality of J2 were 91% ,75% ,50% ,36% and 31% after 24 hours. The difference between these treatments and water control were significant, and as the time went, the mortalities of J2 grew. J2 suspension was inoculated on the centre of a cirele of water agar plate and the filter paper strips soaking up with root diffusate or the metabolites were place at a 3 cm distance around the centre. The results showed that J2 were repelled by 1-10 metabolites according the lowest distribution rates of J2 on 0-1 cm area nearby filter paper strips. In the same area,it showed that J2 were attracted toward the root diffusate according the highest distribution rates. Further more,J2 were significantly lower in the area treated by mixture of root diffusate and 1-10 metabolites than the sterile water（P 〈0.05）. The same result was obtained by using soybean roots or the roots dipped with 1-10 metabolites （P 〈 0.05 ）. It is deduced that 1-10 metabolites can reduce the tendency of soybean cyst nematode toward soybean roots.