An Erwinia-like bacterium pathogenic to leafhoppers

Abstract

The bacterial flora of the leafhopper Colladonus montanus Van Duzee, as reared under insectary conditions, was studied. One predominant bacterial organism was found. This coliform, peritrichously flagellate gram-negative rod was found in high concentrations in dissected guts, but not on external surfaces, of many insects in the stock colonies. Leafhoppers feeding on celery plants infected with Western X-disease virus (WXV) seldom or never carried the organism. It was isolated in high concentration from feces, and leaves contaminated with feces. Healthy adults became infected when caged with infected adults. Leafhoppers could be infected by placing them on plants previously dipped in nutrient broth containing the bacterium. During a period of 1 to 10 weeks after acquisition by feeding, infected leafhoppers died at a greater rate than did uninfected leafhoppers. Five other species of leafhoppers and a spittlebug could be infected with the bacterium. From 1 to 28 days after injection of the organism, depending on the injected concentration, recipient insects died. The bacterium could not be identified with certainty, but failure to decarboxylate lysine, arginine, or ornithine, to reduce nitrate, to utilize raffinose, or to grow on KCN broth, suggest an affinity with the Erwineae.