Background

Nematode is a kind of lower invertebrates distributed widely which can survive anywhere on the earth. According to Hyman (1950) and Poinar (1983)’s estimation, there are over half a million kind of nematodes all over the world. Most soil nematodes are beneficial insects whereas some of them are important plant causative agents so-called plant-parasitic nematodes. Plant-parasitic nematodes have been up to over 5000 species of 200 genus^[1]. Among them, over 100 species of nematodes are damaging the agriculture, forestal and economic crops of China who widely parasitize the roots, stems, leaves, flowers, buds and seeds of manifold plants, harming the development of agriculture and forestry seriously.

According to incomplete statistics, the losses caused by pathogenic nematodes can reach \($\)100 billion every year worldwide^[2]. Meanwhile a newest research by USA indicates that the plant-parasitic nematodes’ damage leads to about \($\)8 billion dollars’ loss to croppers, which takes 12% of the whole value of the crop output. Chinese researchers have done some relevant surveys as well. According to incomplete statistics, 17 provinces such as Anhui, Hainan, Hubei, Gansu, Zhejiang and Fujian have reported root knot nematode (Meloidogyne spp.) disease once, among which the morbidity of some severe regions in Shandong province can up to 2/3^[3]. Pine wood ne