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Mealybug Transmission of Grapevine Leafroll Viruses: An Analysis of Virus–Vector Specificity

August 2010 , Volume 100 , Number  8
Pages  830 - 834

Chi-Wei Tsai, Adib Rowhani, Deborah A. Golino, Kent M. Daane, and Rodrigo P. P. Almeida

First author: Department of Entomology, National Taiwan University, Taipei 106, Taiwan; second and third authors: Department of Plant Pathology, University of California, Davis 95616; and first, fourth, and fifth authors: Department of Environmental Science, Policy and Management, University of California, Berkeley 94720.

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Accepted for publication 3 April 2010.

To understand ecological factors mediating the spread of insect-borne plant pathogens, vector species for these pathogens need to be identified. Grapevine leafroll disease is caused by a complex of phylogenetically related closteroviruses, some of which are transmitted by insect vectors; however, the specificities of these complex virus–vector interactions are poorly understood thus far. Through biological assays and phylogenetic analyses, we studied the role of vector-pathogen specificity in the transmission of several grapevine leafroll-associated viruses (GLRaVs) by their mealybug vectors. Using plants with multiple virus infections, several virus species were screened for vector transmission by the mealybug species Planococcus ficus and Pseudococcus longispinus. We report that two GLRaVs (-4 and -9), for which no vector transmission evidence was available, are mealybug-borne. The analyses performed indicated no evidence of mealybug–GLRaV specificity; for example, different vector species transmitted GLRaV-3 and one vector species, Planococcus ficus, transmitted five GLRaVs. Based on available data, there is no compelling evidence of vector–virus specificity in the mealybug transmission of GLRaVs. However, more studies aimed at increasing the number of mealybug species tested as vectors of different GLRaVs are necessary. This is especially important given the increasing importance of grapevine leafroll disease spread by mealybugs in vineyards worldwide.

Additional keywords: Ampelovirus, Closteroviridae, semipersistent.

© 2010 The American Phytopathological Society