Term of Award

Spring 1991

Degree Name

Master of Science in Biology

Document Type and Release Option

Thesis (open access)

Department

Department of Biology

Committee Chair

Daniel V. Hagan

Committee Member 1

Frank E. French

Committee Member 2

Michael P. Moulton

Abstract

Seasonal abundance and population densities of Culicoides species from sites in Glynn County, Georgia were surveyed using 15 New Jersey light traps during a 9-month period from April-December 1990. Environmental effects on the abundances were also analyzed. The three primary species present were: Culicoides furens (Poey), C. hollensis Mellander & Brues, and C. melleus (Coguillett). C. furens were collected year round, but predominantly during the summer. C. hollensis had a bimodal abundance (spring and fall) . C. melleus also had a bimodal abundance (late summer and fall).

Larval habitats of the primary species were identified from the salt marshes adjacent to two different sites, Sea Island and St. Simons Island. Soil samples were taken from the sites at least monthly from February 1990 through April 1991. Three zones primarily differentiated by elevation, were identified at both of the sites. Most (89%) of the total larvae of all three species combined were found within Zone II caracterized by intermediate (0.3-1.5 m) S. alterniflora Loiseleur and 11% of the total larvae were collected from Zone III characterized by Juncus roemerianus Scheele, Iva frutescens Linnaeus, and Spartina patens (Aiton) Muhl. At Sea Island, 78% of the larvae were collected from Zone II, whereas 22% were collected from Zone III. On St. Simons Island, 97% were collected from Zone II, whereas only 3% were collected from Zone III. No larvae were collected from Zone I at either site characterized by tall Spartina alterniflora (>1.5 m in height).

Soil samples were collected from a salt marsh on the north end of St. Simons Island. Thermal preferences for 3rd and 4th instar larvae of two field collected coastal species, C. furens and C. hollensis were determined. Larvae were placed in an estuarine-water filled (salinity 2.8 g/dl, pH 5.5) stainless steel trough with one end resting on an ice pack (22.60C) and the other resting on a hot plate (42.8"C). Temperature preferendium for C. furens was 30.0- 39.90C (57%, PC. hollensis preferred 20.0- 29.9"C (72%, P <0.05).

Two organophosphates (dibrom and temephos) and two pyrethroids (permethrin and resmethrin) were tested in the laboratory for efficacy of control for biting midge larvae. Field collected larvae from a salt marsh on north St. Simons Island were exposed to four larvicides in either water alone or water with soil substrate. Temephos showed optimal control against biting midge larvae, while having low toxicity on the non-target organisms (other arthropods) tested.

Copyright

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