Factors Affecting the Numbers of Culicoides (Diptera, Ceratopogonidae) in Traps in Coastal Southeast Queensland, With Particular Reference to Collections of Culicoides-Subimmaculatus in Light Traps

Abstract

Hourly light-trap collections, made at Tingalpa Creek, south-east Queensland, on 101 nights over 2.5 years from 30 min before to 3.5 h after sunset, caught 45 414 Culicoides, largely C. subimmaculatus (63%). Sinusoidal curves for annual, lunar and tide cycles, and linear maximum tide height were fitted to logarithmically transformed data. Annual cycles accounted for 44-71% of the between-day variation in catch of C. austropalpalis, C. cordiger, C. henryi, C. histrio, C. longior, C. marmoratus and C. subimmaculatus. Catches of C. subimmaculatus were inversely related to maximum tide height. Catches of the other species were independent of tide. Linear effects of wind speed, temperature, saturation vapour pressure deficit (VPD), cloud cover and time on within-day variation were analysed. Catches of all seven species were inversely related to wind speed but not to the same degree, were independent of VPD and cloud cover, and varied in their dependence on temperature and time. Moonlight increased truck-trap catches of C. subimmaculatus in the third hour after sunset. Activity of female C. subimmaculatus throughout the diel (five trials) varied with the method of assessment: bait, truck trap or light trap. Collections were age graded. All seven grades were caught in the light trap, and empty females dominated the truck trap.