Biological Control Administrator North Carolina Department of Agriculture & Consumer Services Cary, North Carolina
Alligatorweed, Alternanthera philoxeroides, is an invasive aquatic weed that is widespread throughout the southeastern U.S., including North Carolina. A biological control program was initiated throughout the region in the 1960s, and while successful in many southeastern states, establishment of the alligatorweed flea beetle, Agasicles hygrophila, and the alligatorweed thrips, Amynothrips andersoni, was not documented following several releases in North Carolina in the 1960s-1980s. It is known that A. hygrophila is not a cold tolerant species, and North Carolina has historically been in the colder, less suitable range of the beetle’s distribution. However, A. andersoniis more cold-tolerant than A. hygrophila, but the impact of these thrips is often overshadowed in the literature, as they are not as prevalent in areas where A. hygrophila have established. Recently, both A. andersoni and A. hygrophila were recovered from several sites in eastern North Carolina. Both species were documented from sites where releases were last made in 2019, as well as from sites where no releases have occurred. Details of these recoveries, as well as possible mechanisms driving apparent establishment of both species will be discussed.
