The Gonotrophic Cycle of Culicoides Variipennis (Diptera: Ceratopogonidae) and its Implications in Age-Grading Field Populations in New York State, USA1

Abstract

Gonotrophic activity in Culicoides variipennis variipennis from New York State was characterized to establish the reliability of gonotrophic age-grading techniques for determining population age structure. In newly emerged nullipars, follicle maturation to the resting stage required 28–44 h at 22 °C and was not affected by sugar availability. Follicle development to stage V post-blood-feeding did not differ significantly in mated and unmated nullipars. Follicle development in pars was slightly delayed relative to nullipars, but all groups matured eggs in 64–76 h. The development of abdominal pigment and, to a lesser extent, changes in the abdominal tergite pattern, were valid indicators of parity; both conditions were established by stage IV of follicle development. Single follicular relics were visible in all unipars; serial follicular relics were formed in 80–92% of multiparous females. Relics formed by oosorption occur regularly and contribute substantially to the reliability of the Polovodova technique. Field-collection data indicate that parous females may seek blood less than 12 h after oviposition and are at a significantly earlier stage of follicle development than host-seeking nullipars. Females may complete at least 3 gonotrophic cycles under New York conditions.