Preferential landing and engorging sites of Culicoides species landing on a horse in Ireland.

Abstract

An investigation of the landing and engorging sites of midges on a bait horse was made in Ireland as part of a project examining the aetiology of sweet itch. Ten species were recovered, seven of which engorged. Culicoides obsoletus and C dewulfi were the most commonly represented, accounting for 89.9 per cent of midges landing and 90.5 per cent of midges engorging. Only 4.69 per cent of midges attracted to the bait were C pulicaris. Overall, the preferential landing sites for midges were along the mane and lower leg regions. Few culicoides were attracted to the head, front and underside of the animal. Two species, C punctatus and C nubeculosus, fed exclusively at the predilection sites of sweet itch but in very small numbers. C pulicaris fed predominantly at these sites also and represented 5.08 per cent of the engorging catch. Of 10,178 midges attracted to the bait, 4097 (40.3 per cent) engorged; the majority of the species taking full blood meals fed on the mane and lower legs. Midges biting in other areas tended to have smaller meals. Areas along the dorsal midline of the body are predilection sites for sweet itch lesions and are preferential engorging sites also. However, considerable engorgement occurred on the lower legs where sweet itch lesions do not occur.