Population Dynamics Of Nematophagous Fungi In Field

The control effects of bio-control agents were unstable and there were no more details about the population dynamics of nematophagous fungi in field. Real-Time PCR was established to quantify the population of parasitic nematophagous fungi. The population dynamics of nematophagous fungi(Arthrobotrys oligospora, Paecilomyces lilacinus, Pochonia chlamydosporia ZK7) which parasitze in different kinds of samples (rhizospere soil, root, egg mass, females) were assayed, and the results were as follows:Effects of nematode population on bio-control agents:(1) In the high nematode density area, the population of P. lilacinus in soil were twice than the low density area. With the increaseing of nematode in soil, the population of P. lilacinus increased in the same period. The populations of A. oligospora and P. chlamydosporia ZK7 were less than 10 cfu/g. There were no obvious relationship between root-knot nematode density and population of bio-control fungi. (2)In the high nematode density area, the population of A. oligospora, P. lilacinus and P. chlamydosporia ZK7 in root were 100 cfu/g,250 cfu/g and 160 cfu/g, respectively; in the low nematode density area, the populations were 50 cfu/g,150 cfu/g and 30 cfu/g, respectively. With the increaseing of nematode in soil, the population of the fungi increased substantially in the same period.Effects of crops on population of bio-control agents:(1) In the area growing different kinds of plants, the population of A. oligospora in soil were less than 8 cfu/g. while the high population of A. oligospora in root were twice than the low. (2) Only in the area which planting tomatoes that P. lilacinus can be detected in soil. The population of P. lilacinus in the root of bean were 300 cfu/g, while P. lilacinus can be detected in root of other plants occasionally. (3) In the area growing different kinds of plants, the population of P. chlamydosporia ZK7 in soil and in the root of onion were lower than 10 cfu/g. The species of crops had great effect on the population of bio-control agents in root, while in soil, contrarily.Effects of different kinds of agents on the population:(1) In the area of Dalongtan, the experiment group treated with P. lilacinus were twice than control group, the population of P. lilacinus were 7302 cfu/g. While the population of A. oligospora and P. chlamydosporia ZK7 in soil were lower than 10 cfu/g. (2) In the area of Renhe, the population of A. oligospora in the experiment group which treated with Avermectin were 337 cfu/g,350% than control group; the population of P. lilacinus were 4 times than the control. The population of P. chlamydosporia ZK7 in the experiment group treated with P. chlamydosporia ZK7 was 20156 cfu/g,620% than the control. (3) Only the P. lilacinuscan be detected in egg mass and female, the populations were 114082 cfu/g and 67977 cfu/g. The species of bio-control agents had great effect on the population of bio-control agents in root, while in soil, contrarily. P. lilacinuspaly a great role in nematode bio-control.