The Agrotis baculovirus complex: multiple viruses for multiple pests

Larvae of the genus Agrotis (Lepidoptera: Noctuidae) are known to be severe soil pests on a wide range of field crops and vegetables in Europe, Asia and Africa. Agrotis spec. are highly susceptible for a broad number of baculoviruses and in the past, two Alphabaculoviruses (AgseNPV-A (Polish strain), AgseNPV-B (Oxford strain)) and one Betabaculovirus (AgseGV) were isolated from the common cutworm A. segetum. From larvae of the black cutworm A. ipsilon another Alphabaculovirus, Agrotis ipsilon nucleopolyhedrovirus (AgipNPV, Illinois strain), was isolated. Bioassay analysis demonstrated the cross-infectivity of all four baculoviruses for both hosts, which made them potential biocontrol agents for the control of cutworms. Especially in terms of resistance management the usage of a combination of different baculoviruses is regarded to be useful. In order to develop methods for identification of the different viruses we developed a multiplex polymerase chain reaction (PCR) and quantitative PCR (qPCR) based method. The genome of AgseNPV-B was completely sequenced and a comparative genome analysis of AgseNPV-B, AgseNPV-A and AgipNPV was conducted. Phylogenetic analysis confirmed the close relationship of AgseNPV-B and AgipNPV by a high sequence similarity, although the genome length and number of open reading frames (ORF) of AgseNPV-B and AgseNPV-A were more alike. For biological characterization bioassays and the determination of the median lethal dose (LC50) of AgipNPV and AgseNPV for their common host A. segetum, were performed. This work is the basis to analyze the molecular and cellular interaction of these viruses in mixed infections and to optimize the application of these viruses for Agrotis