Greenhouse-based rearing and initial field releases of Jaapiella ivannikovi (Diptera: Cecidomyiidae), a classical biocontrol agent of the exotic Russian knapweed, Acroptilon repens (Asteraceae), in the western US

Russian knapweed, Rhaponticum (Acroptilon) repens (L.) Hidalgo (Asteraceae) is native to Europe and western Asia. R. repens has become a widespread exotic weed in the western US and Canada. It is a long-lived perennial that grows in a variety of mesic and arid habitats, including cropland and rangelands. Classical biological control has been recognized as a potentially-effective management tool for Russian knapweed. One of the first biocontrol agents released in the US is the gall midge, Jaapiella ivannikovi Fedotova (Diptera: Cecidomyiidae). This midge has several generations per year and induces galls at the apical and lateral buds of Russian knapweed shoots. A permit for the US field release of J. ivannikovi was issued in spring 2009, and after quarantine processing, rearing programs were initiated at Montana State University and, later, the USDA-APHIS-PPQ-CPHST Fort Collins Laboratory. These programs are producing J. ivannikovi for field release in the western US. Initial field releases were made in 2009 in Montana (4 sites) and Wyoming (2 sites); in 2010, additional releases were made in Colorado (2 sites), Montana (3 sites), and Wyoming (1 site). Through the end of May 2011, new field releases have been made in California, Colorado, New Mexico, Oregon, and Washington. Preliminary post-release monitoring indicates establishment in Colorado (1 site), Montana (3 sites), and Wyoming (1 site). Thus, J. ivannikovi has been released at 19 sites in seven states, with establishment noted for at least five sites to date. Rearing methods and production schedules will also be discussed.