Galerucella calmariensis L. and G. pusilla Duft were introduced into the United States to control purple loosestrife (Lythrum salicaria L.), an invasive species capable of colonizing wetland ecosystems and displacing native vegetation. Larvae and adults defoliate plants resulting in reduced seed production, stem densities, and ultimately in root crown death. Distribution of beetles within and between wetlands is not well understood. Our objectives were to: 1) map beetle dispersal within a wetland, 2) correlate beetle populations with control of purple loosestrife, and 3) increase efficiency in release efforts by assessing landscape-scale dispersal and colonization of Galerucella spp. In the spring of 2001 and 2002, GPS and GIS technologies were used to map the movement dynamics of Galerucella spp. within each of four wetlands. We also examined the ability of Galerucella spp. adults to disperse from their original release site to other neighboring, noncontiguous, loosestrife-infested wetlands. Geographic regions that contained numerous, noncontiguous loosestrife infested wetlands with at least one site within the region where Galerucella beetles became established were used in this landscape-scale study. Within a wetland we noted that Galerucella spp. dispersed throughout the site within 2 years after initial release. In the landscape-scale study, over 160 sites were sampled in 7 counties. Beetles dispersed up to 7 km and colonized more than 50% of the non-contiguous wetlands from the original release site. Currently, we recommend that resource managers concentrate insect redistribution efforts to wetlands greater than 7 km from known release sites.
Species 1: Coleoptera Chrysomelidae Galerucella calmariensis
Species 2: Coleoptera Chrysomelidae Galerucella pusilla
Keywords: biological control, GIS
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