OCCURRENCE AND TRANSMISSION OF A VIRUS DISEASE OF THE EUROPEAN RED MITE, PANONYCHUS ULMI

Publisher Website
Google Scholar
Abstract
A rod-shaped noninclusion virus infects the European red mite, Panonychus ulmi (Koch), in Ontario. Infection and death can occur in any postovarial stage. Most infected mites contain, in the midgut, more or less spheroidal inclusions with a radiating crystalline structure. Infected mites deposit inoculum on the leaves, probably in excreta or oral secretions at feeding sites, which is picked up orally by uninfected mites while feeding. The inoculum on the leaves is very unstable, seldom remaining infective for more than a week and being almost immediately inactivated after exposure to water. Suspensions of infected mites, triturated in water or various solutions, were inefficient inocula.Introduction of virus into orchard populations of P. ulmi induced epizootics that rapidly reduced the population density. Natural epizootics were found only in dense populations.