Location: Invasive Species and Pollinator HealthTitle: First biological control agent released against Cape-ivy Author
Submitted to: California Invasive Plant Council
Publication Type: Other
Publication Acceptance Date: 3/1/2017
Publication Date: 6/1/2017
Citation: Moran, P.J., Portman, S.L. 2017. First biological control agent released against Cape-ivy. California Invasive Plant Council Newsletter 25(1): 7. http://www.cal-ipc.com/wp-content/uploads/2017/10/Dispatch_2017Spring.pdf
Technical Abstract: Cape-ivy (Delairea odorata, Asteraceae) is one of the worst invasive weeds in California, colonizing riparian, forest, and scrub habitats along the California coast and East Bay hills. Cape-ivy can smother native oaks and other trees, displace native herbs and shrubs, and clog water flow along freshwater creeks. After years of host-specificity testing and environmental permitting, with support from Cal-IPC, the USDA-Agricultural Research Service (USDA-ARS) in 2016 began releasing a shoot tip-galling fly, Parafreutreta regalis (Diptera: Tephritidae) to help control the spread of Cape-ivy. To date, P. regalis has been released at seven sites, ranging from southern Sonoma County to the Big Sur area in Monterey County. Cooperating landowners include the East Bay Regional Park District and several private landowners. Releases are being followed up with visits every few weeks to monitor gall formation, establishment of the fly, and eventually, dispersal and impact of the flies on Cape-ivy populations. Last week, the first open field-produced gall was documented at a site in Sonoma County. Monitoring of existing release sites will continue throughout the winter months. Additional releases will be made next spring and summer as Cape-ivy produces new shoot tips.