Methods for detecting multiple blood-meals in mosquitoes (Diptera, Culicidae)

Two techniques have been developed to investigate the incidence of multiple feeding by mosquitoes. One system detects the ABO blood group substances and can be used up to 24 h after feeding in the case of Anopheles stephensi List. and 30 h for Aedes aegypti (L.). It is limited by cross-reactions which develop between blood group substances as digestion occurs in the stomach of the mosquito. The second system detects the serum protein haptoglobins (Hp) and it is possible to detect the Hp type of blood in single feeds 20 h after feeding for Ae. aegypti and 16 h for A. stephensi. Multiple feeds taken within a short time of each other can be identified up to 16 h after completion of the meal. The minimum amount of blood necessary to effect an identification in a fresh two-part meal is 0·1 mg, which is approximately one-tenth of the total amount of blood taken. It is now therefore possible to measure multiple ‘cryptic meals’ taken from man, if they are of different Hp types. Identification of Hp from A. gambiae sp. A blood-meals has been successfully carried out using material sent from the tropics. Limitations of the techniques as applied to field collections are discussed.