FEEDING AND MAINTENANCE OF SIMULIUM-MEXICANUM (DIPTERA, SIMULIIDAE) IN THE LABORATORY

Methods were developed to feed, maintain, and refeed Simulium mexicanum black flies in the laboratory. Flies were aspirated as they came to feed on horses and calves. The flies were held overnight at 4°C and then attempts made to induce them to feed. Few black flies fed on serum in capillary tubes or through an artificial membrane. Approximately 1/3 of the flies tested fed on rabbits, hamsters, suckling mice, and guinea pigs. Guinea pigs were used most extensively, and 5% to over 80% of the black flies fed. Large cages were unsatisfactory for maintenance of flies after feeding. Survival was best when the flies were individually kept in 4-ml (1-dram) shell vials with fine-mesh screen tops. The vials were kept in beakers covered with wet gauze. The insectary temperature was reduced from 22 ° -26°C to 18°-22°C and survival at 1 week increased from 0.5% to 17%, and maximum survival improved from 8 to 18 days. Approximately 1/2 the black flies that previously fed on guinea pigs and were maintained for 8 or more days refed on other guinea pigs, hamsters, or suckling mice. Three flies were induced to refeed a 3rd time on suckling mice 4-5 days following the 2nd feeding. This method, thus, allows both VEE virus replication and transmission experiments.