The infection of leafhoppers by western X-disease virus: IV. Pathology in the alimentary tract

Abstract

Fourteen days after last-instar nymphs of the leafhopper Colladonus monlanus (Van Duzee) were transferred to celery infected with the peach Western X-disease virus (WXV), lesions could be detected in the epithelium of the first and second ventriculus. After 21–28 days, cytopathological changes could be detected in the filter complex and in the Malpighian tubules, and the lesions in first and second ventriculus were enlarged and more numerous. Cytopathologies in the epithelial cells of the first and second ventriculus became less acute after 4–6 weeks, but Malpighian tubule pathology was more severe and apparently irreversible. The observed pathologies in the first and second ventriculus and in the filter complex involved an insufficient number of cells to suggest a significant role in the lethal effect of the virus on its vector. Adult leafhoppers injected as last-instar nymphs with WXV developed cytopathological symptoms in the Malpighian tubules, but not in other parts of the alimentary tract. However, general deterioration of the first and second ventriculus 30–48 days after injection of WXV resembled effects noted much less frequently in nonviruliferous adults. Crystals accumulated in the lumen of the ventriculus of C. montanus and Fieberiella florii Stål after feeding on celery infected with WXV and in C. montanus upon exposure to plantain infected with aster yellows virus. The occurrence of such crystals was possibly associated with the sloughing of epithelial cells and the production of secretory globules. Effects of starvation, molting, bacterial infection, and host transfer upon the alimentary tract were noted and found to be distinct from the effects of viral infection.