Blood meal source of field-caught Anopheles vector mosquitoes of malaria from Northern Sri Lanka

Host preference in blood-feeding anopheline mosquitoes is crucial in determining malaria vectors. Using a PCR assay that targeted a portion of the Cytochrome b gene of five vertebrates, this study sought to investigate the blood meals of 30 field-caught Anopheles mosquitoes from two Northern Districts of Sri Lanka. Study revealed that blood meals of Anopheles culicifacies and Anopheles subpictus mosquitoes were exclusively from humans (23.3%) and goats (50%), and the remaining 26.6% were mixed blood meals. An. culicifacies (0.65) was more anthropophilic than An. subpictus (0.31), based on the Human Blood Index.  Single-host blood meals were more common in both An. culicifacies (70.6%) and An. subpictus (76.92%) than multiple-host blood meals. A significant association (p<0.05) was observed between the vertebrate source of the blood meal of the mosquito and the frequency of single and multiple-host blood meals taken. While the conventional multiplex PCR assay was more successful in identifying the source of multiple-host blood meals, the nested PCR technique effectively amplified the DNA of single-host blood meals. The mean DNA concentration of mixed-host blood meal extractions amplified by conventional PCR assay (121.8±37.3 ng/µL) was substantially greater (p<0.05) than that of the nested PCR (39.5±29.7 ng/µL). This study reveals important findings which are significant for further exploration into the vectorial capacity of An. culicifacies and An. subpictus, and consequently their transmission potential as malaria vectors in the area. This understanding of the feeding patterns of Anopheles vectors will be helpful for long-term planning and development of suitable, situation-specific malaria control measures in a country.