Seasonal abundance of Culicoides imicola and C. obsoletus in the Balearic islands.

An outbreak of bluetongue (BT) was declared on the Balearic islands of Spain in September and October 2000. In 2001 and 2002, an intensive survey was conducted on cattle farms in Majorca and Minorca for the principal vectors in the Mediterranean Basin, Culicoides imicola and C. obsoletus. Adult Culicoides were collected once a week between June 2001 and December 2002 using CDC light traps. The results from 348 light-trap collections revealed that, in addition to other species of the genus Culicoides, both C. imicola and C. obsoletus appear to be well established on both Majorca and Minorca. Furthermore, both species showed a different seasonal abundance pattern: peak adult populations of C. obsoletus occurred in July, while those of C. imicola peaked in October. These findings indicate that the principal vector in the outbreak of BT in the Balearic islands in 2000 was probably C. imicola.