Effects Of Entomopathogenic Nematodes On The Control Of White Grubs In Honeysuckle Fields

Honeysuckle,one of the bulk medicinal materials for both medicine and food.However,during the production,it is seriously damaged by the soil-dwelling pest white grubs.Entomopathogenic nematodes（EPNs）are important biological control agents,especially for the soil-dwelling pests for they can search the hosts actively.However,the knowledge of EPNs’efficacy against white grubs in honeysuckle fileds is still limited.This paper firstly investigated the dominant species of honeysuckle grub in Pingyi area,screened the high virulent EPN species,and determined the effects of their dose and combination with fungi against white grubs.Then studied the chemotaxis of different EPNs to white grubs with Pluronic F-127 glue.Finally assessed the field efficacy of EPNs or their combination with entomopathogenic fungi for the control of white grubs in honeysuckle fields.The results could provide reference for the green and efficient control of white grubs in honeysuckle fields.The main results are as follows:1.Main species of grubs in honeysuckle fieldThe main adult species conducted by the light trap methods were Anomala corpulenta and Holotrichia parallela.The main white grubs collected from soil in honeysuckle fields in Pingyi area were Brahmina faldermanni,Serica orientalis and H.oblita.Population of white grubs in honeysuckle fields in Pingyi area was high to 1-3/m~2,and the peak was from July to September.2.Toxicity of EPNs and their combination with fungi against white grubsSteinernema longicaudum X-7,Heterorhabditis bacteriophora H06,S.glaseri KG showed high virulence to H.oblita,when compared with S.feltiae SN and H.indica LN2.The corrected mortality of white grub could reach 80.00%at the rate of 400 IJs/larva at 14 d;S.longicaudum X-7 combined with Beauveria brongniartii showed a synergistic effect against white grubs,and the corrected mortality rate of white grubs was 30.00%at 4 d.3.Chemotaxis of different EPNs to white grubsThe invasion rate of different EPNs into white grubs were H.indica LN2>S.glaseri KG>S.feltiae SN>S.longicaudum X-7>H.bacteriophora H06.S.glaseri KG,S.longicaudum X-7 and H.bacteriophora H06 showed significant invasion peaks at 20 h,60 h and 108 h,respectively.showed an increased invasion rate atand all of the three species could deteceted colonization in white grubs at 120 h.However,S.feltiae SN and H.indica LN2 showed no invasion peak and failed to colonize in white grubs.4.Field efficacy of EPNs for the control of white grubs in honeysuckle filedsThe white grub reductions caused by S.longicaudum X-7 and H.bacteriophora H06 at1.0×10~8 IJs/667m~2 at 42 d were 68.69%and 62.18%,which were significantly higher than that cause by S.glaseri KG while with no significant difference with phoxim（77.18%）.S.longicaudum X-7 combined with Metarhizium anisopliae and Beauveria brongniartii could significantly improve the control effect of white grubs in honeysuckle fields.the decrease rate of grubs was 87.20%and 82.24%at 7 d.All nematode-containing treatments still showed effective sustained control effect at 42 d.