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Evidence for Noncirculative Transmission of Pierce’s Disease Bacterium by Sharpshooter Leafhoppers. Alexander H. Purcell, Department of Entomological Sciences, University of California, Berkeley, 94720; Allan Finlay, Department of Entomological Sciences, University of California, Berkeley, 94720. Phytopathology 69:393-395. Accepted for publication 10 October 1978. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-393.

Half of the leafhoppers (Graphocephala atropunctata) allowed acquisition access on grapevines affected with Pierce’s disease (PD) became infective within 2.0 hr, and there was no significant increase in acquisition beyond 24 hr. The median inoculation access period was 3.9 hr. Three of 34 (9%) insects transmitted after 1 hr each for acquisition and for inoculation, which was in close agreement with estimates for which no latent period was assumed. Neither G. atropunctata nor Draeculacephala minerva retained infectivity after molting. The loss of infectivity after molting and lack of a latent period suggest a noncirculative mechanism of transmission of the PD bacterium by leafhoppers.

Additional keywords: Hordnia, Graphocephala, Draeculacephala, lucerne dwarf, alfalfa dwarf, almond leaf scorch, rickettsia-like bacteria, stylet-borne.