Location: Invasive Plant Research Laboratory
2010 Annual Report
Exotic invasive weeds that originate from overseas pose a severe environmental threat to native plants and ecosystems within the United States. The mission of USDA-ARS Invasive Plant Research Laboratory is to find environmentally friendly, biologically based strategies for long-term sustainable management of invasive weeds within the United States. Old World climbing fern, Lygodium microphyllum, is currently recognized to be one of the top three most environmentally damaging invasive weeds impacting natural ecosystems in Florida. The research described below supports the mission of the national program by furthering progress towards development of sustainable management of L. microphyllum. Populations of the brown lygodium moth, Neomusotima conspurcatalis, have survived into their third year and continue to thrive at release sites in Southeast Florida. Vegetation monitoring data has shown that ground cover of Old World climbing fern was reduced by about 50 percent during the first 6 months after the brown lygodium moth was first released, and that cover of the weed has been maintained at these lower levels for at least 6-12 months beyond the initial defoliation. Populations of this tropical moth declined during the winters of 2008 and 2009, likely in response to extended periods of cool weather, although populations recovered during the spring of 2009 and 2010 as the weather warmed up. Parasitism of caterpillars of the brown lygodium moth was first detected during the fall of 2008, and parasitism rates appeared to peak during spring 2009 at about 20 percent, before declining to 10-15 percent during the summer and fall of 2009. To date, most of the parasitoid wasps recovered from caterpillars of the brown lygodium moth have been native wasp species belonging to the family Braconidae, although wasps of a braconid species, Stantonia pallida, introduced from Columbia against a Florida agricultural pest during the 1990’s were also recovered (Kula et al 2010). During spring 2010, new collections of the lygodium moth, Austromusotima camptozonale were made in Australia and were subsequently shipped into quarantine in Fort Lauderdale. These insects will used to support a new field colonization effort during summer 2010. The lygodium sawfly, Neostromboceros albicomus, is currently undergoing regulatory evaluation, and we hope to receive a decision from the Technical Advisory Group for Biological Control of Weeds during summer 2010.