Absence of abdominal pigmentation in species of Culicoides Latreille Subgenus Trithecoides Wirth & Hubert: An obstruction to age-grading

Abstract

Abstract Examination of gravid female specimens of nine species of Culicoides subg Trithecoides, viz C. acanthostomus, C. anophelis, C. flavescens, C. paraflavescens, C. flaviscutatus, C. inornatithorax/flaviscutatus, C. palpifer, C. palpifer/neopalpifer, and an undescribed species, revealed that none possessed the dark abdominal pigmentation characteristic of gravid and parous females of species belonging to other subgenera of Culicoides. The lack of abdominal pigmentation was supported by data from 68 separate collections from 7 countries in southern Asia and Australasia containing more than 4100 female specimens belonging to C. subg Trithecoides, of which none had pigment. This lack of pigmentation is likely widespread within this subgenus and may also be lacking in other subgenera. The lack of abdominal pigmentation hinders the visual age grading of specimens belonging to this subgenus, which will have implications for survival studies and the selection of specimens for viral isolation and detection.