Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/25/2002
Publication Date: 7/19/2002
Citation: Lacey, L.A., Vail, P.V., Hoffmann, D.F. 2002. Comparative activity of baculoviruses against the codling moth, Cydia pomonella, and three other tortricid pests of tree fruit. Journal of Invertebrate Pathology. 80:64-68. Interpretive Summary: Alternatives to conventional chemical pesticides for control of codling moth (CM) are needed for a number of environmental and practical reasons. Other than CM granulosis virus, microbial control agents have received relatively little attention for control of CM. Two major limitations of the virus are its narrow host range and lack of persistence in the orchard due to sensitivity to ultraviolet light. The current study was undertaken to assess the potential of two related insect specific viruses that have relatively broad host ranges. The viruses were 54-93 times less active than the granulovirus, but they were active against 3 additional species of orchard insect pests. Our study reveals the potential for wider application of the broad spectrum viruses, but improvement in virulence will be required before they are of practical value.
Technical Abstract: The granulovirus of Cydia pomonella (CpGV) offers potential for selective control of codling moth, but it has a narrow host range and is very sensitive to UV radiation. Two baculoviruses with broad host ranges within the Lepidoptera are the nucleopolyhedroviruses of the alfalfa looper, Autographa californica (AcMNPV), and that of the celery looper, Anagrapha falcifera (AfMNPV). Comparative assays of CpGV, AcMNPV, and AfMNPV, against codling moth neonate larvae revealed a 54-93 fold greater susceptibility of codling moth to the granulovirus than to the two nucleopolyhedroviruses based on the LC50s for each virus. The LT50 determined for AfMNPV was 3.2 days. Histological examination of tissues in moribund codling moth larvae that had been treated with AfMNPV revealed the presence of nonoccluded and unenveloped virus rods in midgut tissue. No polyhedra nor signs of infection were detected in other tissues. The activity of AfMNPV was also evaluated in obliquebanded leafroller, Pandemis leafroller, and the oriental fruit moth. Codling moth and Oriental fruit moth were significantly more susceptible to AfMNPV than were the two leafroller species.