HOST-SPECIFICITY AND ENVIRONMENTAL-IMPACT OF THE WEEVIL HYLOBIUS-TRANSVERSOVITTATUS, A BIOLOGICAL-CONTROL AGENT OF PURPLE-LOOSESTRIFE (LYTHRUM-SALICARIA)

Introduction of purple loosestrife into North America and its spread into wetlands has led to the degradation of these important habitats for wildlife. Conventional control efforts are unsuccessful in providing long-term control. A classical biological control program offers the best chance for reducing the numbers of this invasive plant and improving regeneration of the native flora and fauna. European studies demonstrated that the root boring weevil Hylobius transversovittatus is highly host specific to the target weed. Attack of two test plant species (winged lythrum and swamp loose-strife) during host range screening was most likely due to artificial test conditions. An environmental assessment of the potential effects of the release of the purple loosestrife borer in North America indicated that benefits outweigh any potential negative impact. Therefore its field release was approved in 1992.