Insecticidal Activity Of Symbiotic Bacteria Of Entomopathogenic Nematodes And The Culture Parameters For Production Of Heterorhabditis Megidis In Liquid Cultures

In this paper, application of entomopathogenic nematodes which obtained from the soil in Gansu Province to control the white grubs was studied, and analyze its symbiotic insecticidal activity. Interaction of five cculture parameters on the yield of Heterorhabditis megidis0627M was determined in liquid cultures. The results were as follows:1In this paper, application of entomopathogenic nematodes to control the white grubs was studied. The three strains of Steinernema and one strain of Heterorhabditis were used assay on Entomopathogenic nematodes to white grubs, making use of ONE ON ONE as methods of indoors experiments. Screening out the best strains of entomopathogenic nematodes Heterorhabditis.megidis0627M to control white grubs in the laboratory, the Steinernema.affine0664YM was second. In the laboratory, using60nematodes/mL, the corrected mortality of Heterorhabditis.megidis0627M was59.9%, Steinernema.affine0664YM’s was35.6%.2Four strains of symbiotic bacteria from Xenorhabdus and Photorhabdus which were isolated directly from three kinds of entomopathogenic nematodes obtained from the soil in Gansu Province.The study evaluated the insecticidal activity of them to Galleria mellonella, and implications of sunlight, ultraviolet radiation and temperature for symbiotic bacteria’s insecticidal activity. The results showed that different symbiotic bacteria have significantly difference in insecticidal activity to Galleria mellonella. The stomach toxicity of Photorhabdus HMP0627was higher than that of others, it’s inhibiting rate of larval weight was36.02%and the mortality was22.20%. Xenorhabdus SAX0664also has higher insecticidal activity. Four symbiotic bacteria strains have good adaption to sunlight and ultraviolet irradiation. They had high stomach toxicity activity to Galleria mellonella in the conditions of 1.999mmol/m2s light irradiation for1hour and ultraviolet ray30minutes. There was significantly difference in different symbiotic bacteria at different time. Symbiotic bacteria’s insecticidal activity was significantly reduced with prolonged culture time. Photorhabdus HMP0627had highly inhibiting rate of larval weight and mortality to Galleria mellonella in the conditions of50℃, Xenorhabdus SKX0657had highly inhibiting rate of larval weight.3Effect of five culture parameters on the yield of Heterorhabditis.megidis0627M was determined in liquid cultures. The results showed that The nematodes produced by TSYS liquid production was collected at the inoculated8d. The research on the culture parameters for production of Heterorhabditis.megidis in liquid cultures results is that:temperature23±1℃, revolving speed180r/min, inoculum size2000IJs/ml.