Susceptibility and tissue specificity of Spodoptera frugiperda to Junonia coenia densovirus

The fall armyworm,Spodoptera frugiperda,which destroys many economic crops such as rice and maize,has recently invaded China.Insect viruses as biological control agents play important roles in killing pests.One potential viral insecticide is the environmentally highly infective and virulent densovirus.We successfully rescued Junonia coenia densovirus(JcDV)using its infectious clone in different insect cell lines and larvae of three insect species.Results showed that the lysate of cultured insect cells transfected by the JcDV infectious clone killed the 2 nd instar S.frugiperda.The LD50 of homogenate from JcDV-infected Spodoptera litura to the 2 nd instar S.frugiperda(1.76×10^(8)viral genome copies per larva during 10 d post infection)was higher than that of the 2 nd instar S.litura(7.39×10^(7)Jc DV genome copies)or Helicoverpa armigera larvae(9.71×10^(7)JcDV genome copies).The LT50 of the S.litura homogenate(2.60×10^(9)viral genome copies each larva)to the 2 nd instar S.frugiperda was 6.96 d,longer than that of the S.litura(6.18 d)or the 2 nd instar H.armigera(5.94 d).JcDV could infect the fat body of H.armigera,but not S.frugiperda or S.litura.Although JcDV can infect all three lepidopteran species,their susceptibility to the virus differs.JcDV has great potential as a biological control agent against pests such as S.frugiperda.