Screening Of Entomopathogenetic Nematodes And Their Virulence To Carposina Sasakii Matsmura

In order to seek efficient strains of entomopathogenic nematodes to control Carposina sasakii Matsmura, more than300soil samples were collected from Hebei province and used for isolating entomopathogenetic nematodes (EPNs). Preliminary screening of isolated EPNs was taken. Effects of8strains of entomopathogenic nematodes against Carposina sasakii Matsmura were determined. The results showed that:1. Eight entomopathogenic nematodes population were isolated and successfully breeded from300soil samples.Four of which belongs to Steinernematidae, four of which belongs to Heterohabditidae.2. The anti-desiccation ability were different in different nematode strains. S.feitiae90had the highest survival rate of19.2%. The survival rate of S.feitiae64and S.feitiae22was more than50%. And the mortality rate to mellonella of recovery nematodes was100%. H.megidis67and H. bacteriophora22strain survival rate was0%.The yields of infective juvenile of eight nematode species in Galleria larvae are different. The number of infective juvenile of S.feitiae90was0.85X106.The number of infective juvenile of H. bacteriophora65was0.31×106.3.The control effects of8strains of entomopathogenic nematodes on Carposina sasakii Matsmura larvae,summercocoon, winter cocoon,were detected.S.feitiae90which showed highest virulence to both among8strains. The mortality of larvae was91.66%after72h.The mortality of summer cocoon was63.6%after10d. The mortality of winter cocoon was60%after10d.The pathogenity of the S.feitiae90of different concentrations to the Carposina sasakii Matsmura larvae,summer cocoon,winter cocoon was also determined. The results indicated that the optimum treatments were12000nematode of Sfeitiae90/mL.4.Coomassie brilliant blue G-250was used to determine the changes in hemolymph protein content of Carposina sasakii Matsmura larvae infected by nematodes. The results showed that hemolymph protein content of the Carposina sasakii Matsmura showed little changes in the early infection. After infection at4h～16h, the protein concentration showed a rising trend and reached the maximum at16h, and then begin to decline. Finally it is significantly lower than that of the control group. The protein content of Carposina sasakii Matsmura larvae in the control group had no significant change with only minor fluctuations in different treatment time.5. During the initial infection stage, the activities of SOD, POD and CAT increased quickly, while during the later stage, the activities of SOD, POD and CAT decreased at different degrees.The activities of SOD, POD and CAT rose first and then gradually decreased.6. The activities of the main detoxifying enzymes changed at different degrees dueto invasion of entomopathogenic nematodes. The activity of GSTs could be summarized as activated→suppressed→activated→suppressed. The impact on AchE activity could be summarized assuppressed→activated→suppressed→activated→suppressed.