Term of Award

Spring 1985

Degree Name

Master of Science in Biology

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Department

Department of Biology

Committee Chair

Daniel V. Hagan

Committee Member 1

Sturgis McKeever

Committee Member 2

Sara Neville Bennett

Abstract

Species of adult Culicoides present and their seasonal incidence on Sea Island, a coastal Georgia barrier island, were monitored using light and conical emergence traps (May 1982-July 1983) and sticky cylinder traps (July 1982-July 1983).

A total of 5446 biting midges representing eight species was collected. The three most abundant species (which comprised more than 99 percent of the total biting midges collected) were C. melleus (Coquillett), C. furens (Poey) and C. hollensis (Melander and Brues). The remaining five species, C. haematopotus Malloch, C. insignis Lutz, C. mississippiensis Hoffman, C. obsoletus (Meigen), and C. venustus Hoffman, comprised less than one percent of the collections.

C. insignis and C. mississippiensis have not been reported previously from Georgia. Presence of C. insignis represents a significant northward range extension of this potential Bluetongue disease vector. The Bluetongue virus affects many kinds of domestic and wild ruminants, but affects most severely sheep and white-tailed deer.

C. melleus occurred in bimodal periods of abundance in spring (April through May) and in late summer-fall (August through November). C. furens occurred in bimodal periods of abundance in spring-summer (April through June) and in summer-fall (June through October). C. hollensis occurred in bimodal periods of abundance in spring (March through May) and in fall (September through December). When compared to air temperature, rainfall, humidity, and vegetation, adult catches showed no statistical correlation with these parameters.

Biting-landing rates of Culicoides spp. were observed on the north end of Sea Island, Georgia over a 12 h period (October 1982) and two 19 h periods (April 1983). Biting activity was crepuscular with bimodal dawn and dusk peaks for C. furens and C. melleus. Biting by C. hollensis was high around dawn and also from 1230 h to 1500 h (15 April). Light intensity and air temperature seem to be the major factors controlling circadian biting activity.

Mouthparts of four species (C. varipennis (Coquillett), C. hollensis, C. furens and C. melleus) were examined. These mouthparts consist of a pair of toothed mandibles, a labrum-epipharynx, a pair of 5 segmented maxillary palps, a pair of laciniae, a hypopharynx and a labium. Principal differences in mouthparts of all four species were that major structures differed in size, as well as number of teeth per mandible, hypopharynx, and lacinia. Mouthparts differed significantly in gross length among all four species studied. No significant differences were found among each species in the number of teeth per hypopharynx, width of hypopharnyx and width of lacina.

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