بررسي بيماريزايي نماد توده هاي STEINERNEMA SP. و HETEROHABDITIS روي كرم سفيد ريشه

Survey on Pathogenicity of Entomopathogenic Nematodes, Steinernema sp. and Heterorhabgitis bacteriophora infesting larval Polyphylla olivieri

Entomopathogenie nematodes in the families. Steinernematidae and heterorhabditis are obligate parasite of many insects and two species Steinernema sp. and Heterorhubitis bacteriophora have been used efficiently for biological control of pests. In order to evaluate the efficacy of entomopathogenic nematodes collected from Polyphyita olivieri larvae in 1998-1999, field experiments arranged in a completely randomized block design. Steinernema sp. and heterorhabditis bacteriophora, nematodes were applied with initial inoculum levels of 0, 2.5*105, 5*105 individual per m2. The experiments were conducted in 6x15 cm pots containing a sandy-loam soil mixture. Nematodes at the mentioned rates suspended in 20 cm^3 distilled water were sprayed on the surface of the soil in the pots. After releasing a third instar larvae in each pot, they were covered with gauze. After 14 days dead larvae were counted in the pots. The results indicated that steinernema sp. and H hacteriophora at the rate of 5* 10^5 individuals per m^2 were able to parasitize 33.33% and 45.37% of the pest larvae respectively.