HOST-SPECIFICITY AND ENVIRONMENTAL-IMPACT OF 2 LEAF-BEETLES (GALERUCELLA-CALMARIENSIS AND G-PUSILLA) FOR BIOLOGICAL-CONTROL OF PURPLE-LOOSESTRIFE (LYTHRUM-SALICARIA)

Many prime wetlands in North America have been degraded following encr oachment by the exotic plant purple loosestrife. Conventional methods are unsuccessful in providing long-term control. Host specificity stud ies demonstrated the suitability of two leaf beetles, Galerucella calm ariensis and G. pusilla, as biological weed control agents. Adults ovi posited only on plants within the genus Lythrum. The only species othe r than purple loosestrife where adult feeding and oviposition occurred and that supported successful larval development was winged lythrum. Swamp loosestrife and winged lythrum may be vulnerable to limited atta ck by newly emerged teneral adults. Evaluation of the potential enviro nmental impact of the two leaf beetles showed that benefits of an intr oduction outweigh potential risks to winged lythrum or swamp loosestri fe. Their field release was approved in 1992.