Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/2010
Publication Date: 9/27/2010
Publication URL: www.tandfonline.com/doi/abs/10.1080/09583157.2010.525739#preview
Citation: Tipping, P.W., Center, T.D., Sosa, A.J., Dray Jr, F.A. 2010. Host specificity assessment and potential impact of Megamelus scutellaris Berg (Hemiptera: Delphacidae) on waterhyacinth (Eichhornia crassipes Mart. (Solms) (Pontederiales: Pontederiaceae). Biocontrol Science and Technology. 21(1):75-87. Interpretive Summary: Megamelus scutellaris is a planthopper from South America that attacks waterhyacinth, one of the world’s worst weeds. This potential biocontrol agent was tested to determine its host range in a series of quarantine-based studies where it was exposed to 64 different plant species including close relatives, economic species, and plant species growing in the same habitats as the target weed. Testing indicated that M. scutellaris can only survive on waterhyacinth in North America. The insect reduced the growth of waterhyacinth by 67% in laboratory tests indicating it has the potential to suppress the plant in the field. A general release permit for M. scutellaris was recently granted and releases have been conducted in Florida.
Technical Abstract: The delphacid Megamelus scutellaris Berg was evaluated for host specificity and potential impact as part of a biological control program targeting E. crassipes. Survival and development of adults and nymphs were used as metrics with no-choice, choice, nymph transfer, and sustainability tests conducted under quarantine conditions. A total of 64 plant species was tested including 12 from the Pontederiaceae (including E. crassipes). Additionally, 27 native and 5 exotic associated wetland species and 11 economic species were tested. Megamelus scutellaris exhibited a high level of oviposition and developmental fidelity to E. crassipes by failing to sustain populations on any non-target test plant past the F1 generation. Nymph transfer tests which simulated potential spill-over events found that survival was virtually non-existent on associated wetland plants, regardless of taxonomic relatedness, including on Pontederia cordata, an important and widespread native species. Eichhornia crassipes plants exposed to two consecutive generations of feeding produced 66.9% less biomass and 73.4% fewer leaves than those in the controls. We conclude that Megamelus scutellaris is safe to release on E. crassipes in the United States. The USDA Animal Plant Health Inspection Service issued a general release permit for M. scutellaris in Feb. 2010 and releases have been conducted in selected locations.