Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2011
Publication Date: 7/7/2011
Citation: Lacey, L.A., Hoffman, D., Federici, B.A. 2011. Histopathology and effect on development of the PoGV on larvae of the potato tuberworm, Phthorimaea operculella (Lepidoptera: Gelechiidae). Journal of Invertebrate Pathology. 108:52-55. DOI:10.1016/j.jip.2011.06.003. Interpretive Summary: The potato tuberworm (PTW) is a world-wide pest of potato in the tropics and subtropics and it is the most damaging insect pest of potato. It can also be a serious pest in temperate zones on an intermittent basis. Eggs and small larvae of PTW are virtually undetectable and may enter potato storage facilities to infest and destroy tubers. A wide variety of chemical insecticides are used against PTW during the growing season but are not permitted to be applied just before harvest or in storage. Scientists at the USDA-ARS laboratories in Wapato, WA and Parlier, CA and the University of California, Riverside, CA determined the pathology of a PTW-specific virus and its effect on PTW development and survival as a potential alternative to pesticides. This information will aid efforts to develop the virus as a component of management of PTW in stored potato facilities.
Technical Abstract: Potato tuberworm (PTW), is a major pest of potato in the tropics and subtropics worldwide. Larvae feed on potato plants and stored tubers and infestations of tubers in rustic storage (i.e. without refrigeration), can result in up to 100% damage. Application of a granulovirus of PTW (PoGV) to stored tubers has been shown to provide significant protection from damage caused by PTW. A substantial amount of research has been conducted on the efficacy of PoGV and environmental factors that affect its activity. However, there has been very little research on the histopathology and affect of the virus on PTW larval development. Only 10 % of larvae emerged from PoGV-treated tubers. Emergence of treated larvae lagged significantly behind that of controls and most of these died within 24-72 h after exiting the tubers. None of the emerged PoGV-treated larvae survived to pupation. Light and electron microscopy showed that the principal tissues infected by the PoGV are the fat body and epidermis. Our observations on the cytopathology of PoGV infection of PTW larvae were consistent with those reported for other GVs One aspect of infection we observed that is not typical of most GVs, as far as is known, was the occurrence of small vesicles distributed between mature GV granules.