Effect of recombinant baculovirus expressing CrV1 protein from Cotesia rubecula bracovirus against Pieris rapae in insecticidal toxicity

Baculoviruses can be genetically engineered to express foreign genes; thus, their lethal potency and host range can be improved to produce more virulent bioinsecticides. Polydnavirus (PDV) genes have insecticidal bioactivities and could enhance the pathogenicity of the baculoviruses to control insect pests. The CrV1 gene from Cotesia rubecula polydnavirus is responsible for depolymerization of actin cytoskeleton in hemocytes, disabling its spread on foreign object surfaces. In this study, we tested the efficacy of the recombinant baculovirus (AcMNPV-CrV1) under p10 promoter against second instar P.rapae larvae. The expression of the CrV1 gene in P.rapae larvae was verified with reverse transcription-polymerase chain reaction (RT-PCR). AcMNPV-CrV1 showed a significantly lower median lethal concentration (LC₅₀) and shorter median lethal time (LT₅₀) as compared with the AcMNPV wild-type virus. These results suggested that the expression of CrV1 protein could successfully improve the insecticidal toxicity of baculovirus.