Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 19, 2004
Publication Date: April 1, 2005
Citation: Crosslin, J., Munyaneza, J.E., Jensen, A., Hamm, P.B. 2005. Association of the beet leafhopper (homoptera: cicadellidae) with a clover proliferation group phytoplasma in the columbia basin of washington and oregon. Journal of Economic Entomology. 98:279-283. Interpretive Summary: In the last few years a disease called potato purple top has become widespread in the potato-producing areas of the Columbia Basin of Washington and Oregon. The disease is caused by a bacteria-like pathogen called a phytoplasma. There are a number of phytoplasmas involved in plant diseases and these are transmitted from plant-to-plant (vectored) by piercing-sucking insects such as leafhoppers and planthoppers. In the case of the potato purple top phytoplasma, which is related to the clover proliferation phytoplasma, the insect vector was unknown. In the research described herein, approximately fifteen species of leafhoppers and planthoppers were collected, identified, and tested for the presence of the purple top phytoplasma. The pathogen was detected most often in the beet leafhopper, genus Circulifer, and occasionally in the leafhopper genus Ceratagallia. This knowledge will allow the insect monitoring and control efforts to be focused primarily on the beet leafhopper, which should lead to improved control of the purple top disease.
Technical Abstract: At least fifteen species in fourteen genera of leafhoppers and delphacids were tested by PCR for the presence of a phytoplasma in the clover proliferation group, designated 16SrVI. Nucleic acid extracts from individual insects or groups of 5-10 were tested using PCR primers designed from the DNA sequence of 16S-23S rRNA or ribosomal protein genes of the pathogen. Of the insect species tested, the beet leafhopper, Circulifer tenellus (Baker) was most often associated with the phytoplasma, with approximately 16% of the insects testing positive. The phytoplasma was occasionally found associated with Ceratagallia spp. The detected phytoplasma was similar to, or synonymous with, the beet leafhopper-transmitted virescence agent (BLTVA) that causes the potato purple top disease in the Columbia Basin region of Washington and Oregon. Leafhopper species which were not associated with the phytoplasma included Macrosteles spp., Dikraneura spp., Colladonus montanus (Van Duzee), C. geminatus (Van Duzee), Ballana spp., Amplysellus spp., Paraphlepsius spp., Texananus spp., Balclutha spp., Latalus spp., Erythroneura spp., Exitianus exitiosus (Uhler), and unidentified Delphacids. The association of the phytoplasma almost exclusively with the beet leafhopper suggests that this insect is the major vector of the phytoplasma in this region.