Influence of high temperatures on the pathogenicity and survival of Western X-disease virus in leafhoppers

Abstract

Temperatures of 38° and 41° during periods of 7–20 days inactivated Western X-disease virus (WXV) or reduced the virus titer in the leafhopper vector Colladonus montanus (Van Duzee). Insects that were inoculative prior to 20 days of heat treatment required a second virus incubation period of several weeks following heat treatment before they again transmitted virus. In contrast, the control insects held in the greenhouse transmitted virus immediately, and their transmission curve declined with increasing time. The second incubation period was longer in insects that had acquired virus by feeding than in those receiving virus by injection. The longevity of viruliferous leafhoppers was also affected by heat treatment. Although longevity was best among virus-free, unheated leafhoppers and second best among virus-free heated insects, viruliferous leafhoppers tested for longevity after heat treatment consistently lived longer than did the viruliferous but unheated controls. The results suggest that the pathological effects of WXV in some of the vectors may be temporarily arrested or retarded when the virus is inactivated or the titer is reduced by means of heat treatment.