Biocontrol Of Snail And Lepidoteran Insect Pests By A Combination Of Firefly And Entomopathogenic Fungi

Here we provide a novel technology of biological control.We used larvae of Pyrocoelia analis as the carrier of entomopathogenic fungi to snails and Lepidoptera pests.In this study,we performed some experiments to exploit this novel method.We measured the impact on P.analis,which led by a commonly used pesticide imidacloprid.Screening entomopathogenic fungi which could be used in this biological control method.The ability of P.analis to carry fungal spores and the effect of carrying spores on predation efficiency of P.analis were tested.We tested the efficiency of P.analis larvae as a vector of B.bassiana to simultaneous control of insects.Transcriptome ananlysis were used to explore the immune response mechanism of dealing with microorganism in P.analis.The main results are as follows:(1)P.analis larvae are sensitive to pesticides.Imidacloprid has highly toxic for the third instar larvae of P.analis.One-five-hundredth of the recommended concentration(0.1 mg/L)of Imidacloprid can cause P.analis larvae poisoned and continuing luminescence.Poisoning can cause the damage of histological structure and producing excess reactive oxygen species until the larvae dead.(2)Beauveria bassiana LY2 were selected as the entomopathogenic fungi carried by P.analis.LY2 led to 0%mortality for the third-instar larvae of P.analis within two weeks,and85.56±0.90%and 76.67±1.57%adjusted mortality for Plutella xylostella and Spodoptera litura respectively.In addition,we found that P.analis larvae had high resistance to fungi.And the RNA-seq analysis helped us understand P.analis larvae with high resistance of fungi,and presented the evidence of the novel technology of biological control.(3)P.analis larva has the ability of carrying conidium of entomopathogenic fungi.The third-instar larvae of P.analis were capable of carrying 1.9×10~7 spores after through a release device.These spores would be lost due to predation and other activities of the third-instar larvae of P.analis,and the loss rate of spores reached 95%on the eighth day.(4)The method,based on P.analis larva carrying B.bassiana spores,presented significantly control efficiency for P.xylostella and S.litura.The corrected mortality rates of snail,P.xylostella and P.xylostella were 97.78±1.81%,60±3.14%and 48.89±4.80%,respectively,which were significantly higher than those of the control group within two weeks in the greenhouse.These results indicate that the P.analis larvae have high resistance of entomopathogenic fungi and can be used as carriers of entomopathogenic fungi.The entomopathogenic fungi carried by P.analis can effectively control snails and other lepidopteran pests.However,this method could not be used with imidacloprid and other pesticide,because P.analis has sensitivity of imidacloprid.Firefly should not be combined with pesticides such as imidacloprid.Before using this method,it is necessary to investigate whether pesticides such as imidacloprid have been used in the field recently.