Digestive Processes Of Hematophagous Insects: VIII. Estimation of meal size and demonstration of trypsin in horse flies and deer flies (Diptera: Tabanidae)

Abstract

Blood-meal sizes are given for 12 species of tabanids (2 Chrysops and 10 Hybomitra ). In each species the average amount of blood ingested by the females was approximately equal to their average unfed weight. However, there was no significant intraspecific correlation between the unfed weight of a female and the amount of blood ingested. Females of Hybomitra affinis (Kirby), Hybomitra arpadi (Szilady), and Hybomitra lasiophthalma (Macquart) took larger meals when they fed upon man than when they fed upon rabbit or upon defibrinated beef blood through a Silverlight membrane. Under certain circumstances the diverticulum was used as a reservoir lor blood. Trypsin was demonstrated in 13 species (5 Chrysops , 7 Hybomitra and Haematopota americana Osten Sacken). In H. affinis (at 25°C), the maximum amount of trypsin occurred 24 to 48 hr after ingestion and there was a significant correlation between trypsin activity and protein content of the midgut.