Homalodisca vitripennis Germar 1821a: 61Membracoidea : Cicadellidae
|Diseases Transmitted||Pathogen Type|
|Crops Affected by Homalodisca vitripennis Germar 1821a: 61|
This species is a vector of phony peach disease virus and Pierce’s disease virus of grape in Georgia. Transmission of phony peach disease virus was first reported by Turner and Pollard (793) in 1955 under the name of “Homalodisca triquetra (Fabricius) .“ Eight definite and 8 probable cases of transmission were obtained in 203 trees tested. Later, in 1959, Turner and Pollard (795) confirmed transmission by this species under the name of “Homalodisca coagulata (Say) .“ Percent efficiency in experimental transmissions varied from 14.8 to 24.4. A higher percentage of transmission was obtained from plum than peach when these plants were used concurrently as sources of inoculum. Although the exact minimum acquisition feeding period was not obtained, there was evidence that 3 to 4 days were as adequate as longer periods. The latent period in the vector’s body varied considerably and in some tests was extremely long. During several tests in which leafhoppers were collected directly from peach trees in the field and placed on healthy trees, the latent period varied in the first test from 34 to 50 days, second test 58 to 85 days, and third test 86 to 110 days. The vector was most efficient in transmitting the virus in June as evidenced by 45-percent transmission obtained during that month in comparison to 18 percent in July and 12 percent in August.
Kaloostian et al. (408) were first to confirm this species as a vector of Pierce’s disease virus of grape in Georgia in 1962. A 3-day virus acquisition and 21- to 105-day transmission feeding periods were reported. Earlier in 1957, Crall and Stover (148) obtained transmission of this virus, but they were unable to determine whether they were using coagulata, or insolita, or both species in their tests.
This species is considered the most important vector of phony peach disease virus in view of its direct association with peach orchards and its superiority over other species in ability to transmit the virus naturally. It is also considered an important vector of Pierce’s disease virus of grape in Georgia.
Very large, robust species. Length of male 11.50—12.50 mm., female 11.80—13.80 mm.
General color brown to black. Crown, pronotum, and scutellum brown or black with numerous ivory or yellowish spots, surface coarsely rugulose; elytra subhyaline.
Pygofer in lateral aspect about 11/4 times longer than wide, caudal margin broadly convex; aedeagus in lateral aspect with two pairs of terminal processes, lateral pair short, curved, broad subapically, serrate on apical margins and projecting caudad, caudal pair long, narrow, attenuated apically and projecting dorsally; gonopore dorsal; style in dorsal aspect simple, finely serrate on lateral margins at apical half; female seventh sternum in ventral aspect with caudal margin deeply and sinuately excavated (fig. 24).
This species is closely related to Lacerta in general habitus and genital characteristics and can be separated by the aedeagus with the curved lateral atrial processes, which are serrate distally. References to this species as triquetra by American authors are erroneous. Schroder in 1957 (669) first suppressed coagulata as a synonym of vitripennis (Germar), but in 1958 Young (881) resurrected coagulata and stated that triquetra was a valid South American species and did not occur in the United States. (Nielson 1968)
|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.|