Vector ecology informs epidemiology: implications of glassy-winged sharpshooter oviposition behavior and nymphal dispersal from oviposition sites on epidemiology of Xylella fastidiosa

Authors: Sisterson, Mark; Uchima, Sean

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/3/2025
Publication Date: 1/11/2026
Citation: Sisterson, M.S., Uchima, S.Y. 2026. Vector ecology informs epidemiology: implications of glassy-winged sharpshooter oviposition behavior and nymphal dispersal from oviposition sites on epidemiology of Xylella fastidiosa. Journal of Economic Entomology. 119(2):1003-1014. https://doi.org/10.1093/jee/toaf352.
DOI: https://doi.org/10.1093/jee/toaf352

Interpretive Summary: Several epidemics of Pierce’s disease of grapevine in California were associated with large populations of an insect vector (glassy-winged sharpshooter). In severely affected vineyards, diseased grapevines were reported to be aggregated along rows. Aggregation of diseased grapevines along rows is consistent with spread occurring by insect vectors walking to neighboring vines via the overlapping canopy. To quantify the risk of glassy-winged sharpshooter nymphs walking between grapevines, glassy-winged sharpshooter nymphal dispersal distances were estimated. Results indicated that glassy-winged sharpshooter nymphs routinely disperse away from oviposition sites in search of higher quality host plants and that nymphs may move up to 4.4 m away from the oviposition site during the first instar. Given the estimated dispersal distances of glassy-winged sharpshooter nymphs, it is likely that nymphs contribute to within field spread of the causal agent of Pierce’s disease.

Technical Abstract: For an insect-transmitted pathogen to spread, the vector must feed on an infected plant to acquire the pathogen and subsequently disperse and feed on a healthy plant. Because juvenile insects are wingless and adults are typically winged, adult insects are assumed to disperse greater distances and therefore have a greater contribution to pathogen spread. The glassy-winged sharpshooter (Homalodisca vitripennis) transmits Xylella fastidiosa, a bacterial plant pathogen that causes several plant diseases including Pierce’s disease of grapevines. For many insects, preference for oviposition hosts is directly related to offspring performance on that host. However, studies have documented that glassy-winged sharpshooter ovipositional preference is not linked to offspring performance. One hypothesis for the lack of an association between oviposition preference and offspring performance by the glassy-winged sharpshooter is that nymphs disperse from oviposition sites shortly after egg hatch. Because glassy-winged sharpshooter nymphs are capable of transmitting X. fastidiosa, routine nymphal dispersal could contribute to secondary (plant-to-plant) pathogen spread. Vertical and lateral dispersal of glassy-winged sharpshooter nymphs from oviposition sites on preferred and non-preferred hosts was quantified. In vertical movement tests, majority of nymphs moved upward into the grapevine canopy shortly after egg hatch, with faster dispersal away from less preferred plants. In lateral movement tests, hourly dispersal rates were greater on the less preferred plants than on the preferred plants, with nymphs dispersing from non-preferred plants and congregating on preferred plants. Results indicate that glassy-winged sharpshooter nymphs routinely disperse from oviposition sites shortly after egg hatch in search of higher quality host plants. Such routine nymphal dispersal may contribute to secondary (plant-to-plant) pathogen spread in managed and natural systems.