VIEW ARTICLE

Vector Relations

Entry of Ingested Plant Viruses into the Hemocoel of the Beetle Vector Diabrotica undecimpunctata howardi. R. Y. Wang, Department of Plant Pathology, University of Arkansas, Fayetteville 72701; R. C. Gergerich, and K. S. Kim. Department of Plant Pathology, University of Arkansas, Fayetteville 72701. Phytopathology 84:147-153. Accepted for publication 23 October 1993. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/Phyto-84-147.

Southern bean mosaic sobemovirus (SBMV) and the cowpea strain of tobacco mosaic tobamovirus (CP-TMV) are found in the hemocoel of some beetle vectors after they have fed on infected plants. The location in the alimentary canal through which ingested plant viruses enter the hemocoel of the spotted cucumber beetle Diabrotica undecimpunctata howardi was studied. Immunofluorescent and electron microscopy were used to detect the presence of ingested viruses in the gut lumen and the epithelial cells lining the midgut of the spotted cucumber beetle. Virus-specific immunofluorescent microscopy detected bean pod mottle virus and tobacco ringspot virus only in the lumen of the gut; these two viruses cannot be detected in the hemocoel. In beetles from which virus was recovered from the hemocoel, SBMV and CP-TMV were found both in the lumen of the gut and in the epithelial cells of the midgut. CP-TMV was observed by electron microscopy both in the epithelial cells of the midgut and in the hemocytes of the beetles that had acquired the virus. This suggests that plant viruses enter the hemocoel of the beetle through the peritrophic membrane-lined midgut but not through the cuticle-lined foregut or hindgut.