Helochara communis Fitch 1851a: 56Membracoidea : Cicadellidae
|Diseases Transmitted||Pathogen Type|
|Crops Affected by Helochara communis Fitch 1851a: 56|
This species is a vector of Pierce’s disease virus of grape in California. Frazier (273) was first to report this species under the name “delta” as a vector of this virus in 1944. Hewitt et al. (362) confirmed transmission in 1946 by reporting infections of alfalfa dwarf virus to 12 out of 26 plants tested and Pierce’s disease of grape to 7 out of 11 vines tested. Leafhoppers fed on diseased plants from 1 to 3 days and for 2 to 3 days on healthy test plants at successive intervals. During a 4-year period percent transmission from diseased grape to healthy grape and alfalfa was 56 and 49, respectively, and from diseased alfalfa to healthy grape and alfalfa 57 and 62, respectively. Among 2,000 specimens in 13 lots tested, only 8 percent were naturally infective. Further studies on transmission of Pierce’s disease virus by Freitag and Frazier in 1954 (286) showed that certain collections made during 4 years from Tulare County in the Sierra Nevada Mountains were naturally infective. Among 98 lots tested 13.3 percent were infective. The infective specimens were taken from grass bogs at an elevation of 7,000 feet.
This species is not considered an important vector of this Virus owing to the remoteness of its natural habitat to grape vineyards.
Medium size, slightly robust species. Length of male 4.60—4.80 mm., female 5.40—6.00 mm.
General colour light green to dark green. Body coarsely pitted.
Pygofer in lateral aspect about 1½ times as long as wide, dorsal margin slightly concave, caudodorsal margin produced posteriorly to round lobe; aedeagus in lateral aspect simple, sinuate, tubelike, narrowed throughout, shaft narrowed basally and broad distally in ventral aspect, notched apically; gonopore large, subapical on dorsal surface of shaft; paraphyses symmetrical with two pairs of processes, terminal pair about three times as long as basal pair and crossing over at apex; style in dorsal aspect simple, apex sharply pointed; female seventh sternum in ventral aspect with distinct spatulate process on caudal margin.
Since this is the only species in the genus Helochara that is a vector of a plant virus, it can be separated from other species by characters in the key to the genera. The male genitalia were illustrated by DeLong and Severin in 1949 (197). In comparing the genitalia with authentically determined specimens of communis Fitch, I find no basis for retaining delta as a distinct species and therefore have suppressed it under communis. The repository of Fitch’s type is unknown.
|Nielson, M. W. 1968b. The leafhopper vectors of phytopathogenic viruses (Homoptera, Cicadellidae). Taxonomy, biology and virus transmission. United States Department of Agriculture Technical Bulletin . 1382 386 pp.|