PRIMARY INFECTION OF INSECT TRACHEAS BY AUTOGRAPHA-CALIFORNICA-M NUCLEAR POLYHEDROSIS-VIRUS

Previously we found that Autographa californica M nuclear polyhedrosis virus infections initiated in the midguts of insect hosts are dissemi nated within the hosts via tracheas, elements composing the insect res piratory system. Herein we report that infection of tracheas also can be initiated directly via the spiracles, exterior openings of the trac heal system to the atmosphere. Infections were initiated both by direc t application of viral inoculum to the spiracles and by aerosol. Infec tions established by both these methods appeared to advance much more rapidly than infections established by the oral route, and a host high ly refractory to infection orally was easily susceptible to direct tra cheal infection. These findings are important for continuing efforts t o improve the use of baculoviruses as pest control agents; they also e stablish the possibility that direct tracheal infection via aerosol ma y facilitate horizontal transmission of baculoviruses during natural e pizootics. (C) 1994 Academic Press, Inc.