Date of Award

12-2007

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Entomology

Advisor

Morse, John C

Committee Member

Adler , Peter

Committee Member

Whetstone , Jack

Abstract

Arthropod communities inhabiting feral water-hyacinth rafts were surveyed monthly in South Carolina's Coastal Plain from March 2005 through February 2006. Special attention was given to the chevroned waterhyacinth weevil [Neochetina bruchi (Hustache)], the mottled waterhyacinth weevil [N. eichhorniae (Warner)] (both Coleoptera: Curculionidae), and the waterhyacinth moth [Niphograpta albiguttalis (Warren)] (Lepidoptera: Crambidae), which were imported into North America to control water-hyacinth. Communities of arthropods are compared among sites, flow regimes (lentic, lotic, and tidal), and months of the year. The arthropod communities in waterhyacinth rafts in South Carolina are more diverse than previously reported. Rafts in each of five freshwater systems contained numerous species that were unique to each ecosystem. Water-hyacinth rafts in lentic and lotic systems produced similar arthropod abundances and diversities and contained arthropod assemblages with similar feeding strategies. Rafts that were repeatedly stranded on river banks in tidal waterways contained fewer species than lentic and lotic sites. Tidally stranded plants contained different arthropod assemblages with reduced frequencies of collectors-gatherers, collectors-filterers, and shredders-detritivores and increased frequencies of predators and shredders-herbivores. Arthropod species richness and abundance remained relatively constant throughout the year at each site, with minor fluctuations that coincided with the emergences of Odonata and chironomid Diptera in late spring and early summer. Seven species of aquatic insects are reported as new records for South Carolina. Though none of the three imported biological control agents have ever been released in South Carolina, 3 all were collected. Niphograpta albiguttalis was not collected at the regular study sites but was recorded during initial surveys in 2004. Both of the Neochetina weevil species were collected at all seven study sites during this study. Weevil abundances varied among sites and between species. Neochetina eichhorniae was significantly more abundant than N. bruchi at two sites, and the two species were about equally abundant at the five remaining sites. Weevil abundances were similar at lentic and lotic sites but were slightly reduced in tidally stranded rafts. An inverse, temporal relationship occurred between abundances of adult weevils and their larvae. In addition, descriptions and illustrations of the larvae of the water-hyacinth weevils are provided for discriminating between the two species.

Included in

Entomology Commons

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