Baculoviruses for the biological control of cutworms (Agrotis spp.)
Abstract: Caterpillars of the common cutworm Agrotis segetum and black cutworm A. ipsilon(Lepidoptera: Noctuidae) are wasteful feeders of various crops in agriculture. These cutwormsare mainly controlled by chemical pesticides but recent attempts are aimed to control these soilpests by the application of baculoviruses. Four different baculoviruses, namely Agrotis segetumnucleopolyhedrovirus A (AgseNPV-A), Agrotis segetum nucleopolyhedrovirus B (AgseNPV-B),Agrotis ipsilon multiple nucleopolyhedrovirus (AgipMNPV) and Agrotis segetum granulovirus(AgseGV), were isolated from larvae of A. segetum and A. ipsilon and are considered as potentialbiocontrol agents. In natural infections, larvae of both hosts are susceptible to all four viruses andindividual caterpillars of the common cutworm were observed to become in infectedsimultaneously by AgseNPV-B and AgseGV. Co-infections may be advantageous in terms ofvirulence and resistance management, although the level of interaction is critical. To test for amutualistic, neutral or antagonistic interaction and to evaluate a combined application of Agrotis-specificbaculoviruses, we exemplary performed mixed infection experiments of A. segetumlarvae that were exposed to AgseNPV-B and AgseGVat different concentration. For quantitativeanalysis of the outcome of mixed infections as well as for quality control in virus production areliable method for detection and discriminative quantification for Agrotis-specific baculovirusesis required. We established a multiplex PCR analysis based on highly specific oligonucleotideswhich also permit quantification by quantitative PCR. As a prerequisite of these studies thegenome of AgseNPV-B was completely sequenced by 454 sequencing technique. Comparativegenome sequence analyses gave a detailed insight into the molecular setup of the three Agrotis-specificNPVs and confirmed that they can be regarded as three different but close relatedspecies. Our results will help to develop and evaluate Agrotis-specific baculoviruses as biocontrolagents and to understand the evolutionary co-existence of viruses that are highly adapted to thesame hosts.