Sugar Feeding by Female Tabanids (Diptera: Tabanidae) and its Relation to Gonotrophic Activity

Abstract

Developmental stages of terminal follicles and parity were determined for 1311 blood-seeking females of 17 Chrysops , 7 Hybomitra , and 7 Tabanus species in Connecticut during 1978 and 1979. Nulliparous individuals with stages I, I–II, or 11 follicles were observed in 29 species; nulliparity (n ≥ 50 dissections) ranged from 28.7% of 181 Hybomitra lasiophthalma to 90% of 160 Chrysops vittatus . Anautogeny prevails in inland populations of tabanids at this locality. Cold anthrone reagent detected fructose and/or sucrose in 71% of 799 nulliparous and in 72.3% of 512 parous specimens. Prevalence of sugar-positive females (n ≥ 24 tested) ranged from 58% in H. sodalis to 92% in C. cincticornis . In an additional 366 tabanids analyzed by thin-layer chromatography, 55.9% of 345 positives had glucose, fructose, and sucrose, 38.3% contained glucose and fructose, and 5.8% showed glucose alone. Of the 1677 females tested by either method, 72.9% contained fructose and/or sucrose. Results indicate extensive feedings on sugars and suggest that these carbohydrates are essential dietary nutrients.