Disease Note.

Two New Beetle Vectors of Physalis Mottle Virus.. F. Can, Department of Plant Pathology and Crop Physiology, Louisiana Agricultural Experiment Station, Louisiana Stale University Agricultural Center, Baton Rouge 70803. R. A. Valverde, and M. C. Rush. Department of Plant Pathology and Crop Physiology, Louisiana Agricultural Experiment Station, Louisiana Stale University Agricultural Center, Baton Rouge 70803. Plant Dis. 78:432. Accepted for publication 13 January 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0432B.

The flea beetle (Epitrix cucumeris Harris) has been reported as a vector of Physalis mottle virus (PhyMV) in Louisiana. Two other beetle species commonly found in tomatillo (Physalis ixocarpa Brot. ex Hornem.) fields were tested as vectors. The banded cucumber beetle (Diabrotica balteata LeConte) and the palestriped flea beetle (Systena blanda Melsheimer) were collected from tomatillo and cowpea in experimental fields in Baton Rouge. Virus transmission tests were conducted under greenhouse conditions. Beetles were starved for 2 hr and placed individually in test tubes containing tomatillo leaves infected with PhyMV. After a 24-hr feeding period, each beetle was transferred to a 3-wk-old healthy tomatillo planl and covered with a plastic cup. After a 24-hr transmission feeding, the beetles were removed. Leaf samples from test plants were collected after 2 wk and tested serologically with PhyMV antiserum using the Ouchterlony double-diffusion test. PhyMV was transmitted by four of 100 D. balteata and two of 50 S. blanda. Similar experiments conducted with E. cucumeris resulted in a higher percentage of virus transmissions (11 of 50 beetles). Plants that were positive by serology showed typical symptoms of PhyMV. Despite the low transmission efficiency under experimental conditions, high populations of these beetles during the summer could explain the high incidence of PhyMV in tomatillo.