Impact of freezing on the emergence of Culicoides chiopterus and Culicoides dewulfi from bovine dung.

The emergence of Culicoides chiopterus (Meigen), 1830 and C. dewulfi Goetghebuer, 1936 (Diptera: Ceratopogonidae) from cowpats in northwestern Germany was investigated. In order to investigate the survival of both species at low temperatures, cowpat subsamples were frozen for 48h at -18 and -21°C. Emergence from frozen and non-frozen samples was compared. The number of emerging adults of C. chiopterus from samples frozen at -18°C was greatly reduced and no emergence was observed from samples frozen at -21°C. No adult C. dewulfi emerged from frozen samples, suggesting this species is less resistant to these temperatures, compared to C. chiopterus.