Factors affecting numbers of Culicoides in truck traps in coastal Queensland

Truck trap collections of Ceratopogonidae were made over a period of 27 months (November 1973-February 1976) at Tingalpa Creek, in southeast Queensland, Australia. Six collections were made on each of 95 days, giving 570 observations and a total of 29,378 Culicoides. Two collections were made before, one at, and three after sunset. Separate analyses were made of the catches of thirteen entities: male and female C. austropalpalis, C. brevitarsis, C. marksi, C. marmoratus and C. victoriae, female C. henryi and C. longior, and total C. bundyensis. Catches were dominated by C. brevitarsis (35.2%) and C. marmoratus (32.3%) and, with C. victoriae, were taken on almost every collecting day over all seasons. Sex ratios (M:F) varied from 0:100 for C. longior to 130:100 for C. marksi. Collections of all entities, except female C. henryi, were greatest (50-70% of the daily catch) at sunset. In winter there was substantial activity in the hour before sunset. Time of day was the most important variable, accounting for 15-45% of the observed variation. Between-day differences were significant for all except C. austropalpalis, C. victoriae and male C. marksi. Culicoides brevitarsis, C. bundyensis and C. longior had highly significant annual cycles, C. victoriae and female C. austropalpalis had significant lunar cycles, and C. longior had a significant tidal cycle. Logarithms of catches of female C. austropalpalis, C. brevitarsis, C. henryi, C. marmoratus, and female and male C. victoriae were inversely related to linear wind speed. Log catches of female C. austropalpalis, C. brevitarsis, C. marmoratus and C. victoriae, and male C. marksi and C. victoriae were positively related to temperature (quadratic).