|GRODOWITZ, M - Us Army Corp Of Engineers (USACE)|
|Dray, F Allen|
|O'BRIEN, C - University Of Arizona|
|JOHNSON, S - Louisiana State University|
|COFRANCESCO, A - Us Army Corp Of Engineers (USACE)|
Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2012
Publication Date: 3/1/2013
Publication URL: http://www.bioone.org/doi/full/10.1653/024.096.0124
Citation: Center, T.D., Parys, K., Grodowitz, M., Wheeler, G.S., Dray Jr, F.A., O'Brien, C.W., Johnson, S., Cofrancesco, A. 2013. Evidence of establishment of Bagous hydrillae Coleoptera: Curculionidae), a biological control agent of Hydrilla verticillata (Hydrocharitales: Hydirocharitaceae) in North America?. Florida Entomologist. 96(1):180-186.
Interpretive Summary: A small aquatic weevil was released during the 1990s as a possible control of the submersed aquatic weed Hydrilla verticillata (hydrilla). Despite the release of over 300,000 weevils, we were never sure whether or not it had established in the field. However, in 2009 other researchers working on a different aquatic weed in southern Louisiana picked up two specimens of the hydrilla weevil, which was identified by a expert on the taxonomy of this group of weevils. This confirms that the weevil did, in fact, establish although in numbers too low to suppress hydrilla.
Technical Abstract: The semi-aquatic weevil Bagous hydrillae was released during 1991-1996 at 19 sites in four states in attempts to control the aquatic weed hydrilla, Hydrilla verticillata. Fourteen of the sites were in Florida, two each in Texas and Georgia and one site in Alabama. Over 320,000 adult weevils were included in these releases. Despite the fact that a few adults were recovered as late as 4.5 years post-release, presence of permanent, self-perpetuating populations was never confirmed. Then, during 2009 adult B. hydrillae were collected in southern Louisiana, at least 580 km from the nearest release site and 13 years after attempts to establish this insect had terminated. This suggests that earlier recoveries were indicative of successful establishment and that this weevil species has persisted and dispersed widely in the southeastern USA. Nonetheless, there is no evidence that it has had a suppressive effect on hydrilla.