Prevalence of mixed blood meals and double feeding in a malaria vector (Anopheles sacharovi Favre).

A study was undertaken in a Greek village during 1970 to determine the degree of mixed feeding in a population of Anopheles sacharovi Favre. Exhaustive precipitin testing of 1 025 bloodmeals from 5 sites representing 3 different biotopes revealed that 91 (8.9%) of the 1 021 positive meals contained blood from 2 serologically distinct hosts. In a routine survey in 1971, when the testing was not as exhaustive, mixed meals were detected in only 2 (0.1%) of 1 798 smears tested. In the 1970 study, no mixed meals were found in pit-shelters, suggesting that a mosquito interrupted while feeding out of doors tends to move to an indoor biotope to complete its meal. A portion of the multiple meals -i.e., those completed on the same host species-could not be detected by the precipitin test. The frequencies of these "cryptic" multiple meals were calculated for the three main biotopes studied. The human blood index derived from these tests suggests that, in the absence of insecticidal spraying for 10 years, the host selection pattern of the mosquito had reverted to that found before the malaria eradication programme in Greece commenced.