WEIGHT-GAIN, HEMOGLOBIN UPTAKE, AND VIRUS INGESTION BY HYALOMMA-TRUNCATUM (ACARI, IXODIDAE) TICKS AFTER ENGORGEMENT ON VIREMIC GUINEA-PIGS

The ability of guinea pigs to serve as a source of an arbovirus for fe eding ticks was examined with Hyalomma truncatum Koch and Venezuelan e quine encephalomyelitis virus. Ticks fed on guinea pigs to varying deg rees, as indicated by both low and high weight gain and hemoglobin upt ake. Pools of larval ticks measured at drop-off with undetectable or v ery low hemoglobin levels (mean hemoglobin content = 0.05 mg per pool) contained the same amount of virus (>10(3.0) plaque-forming units [PF U] per pool) as pools of ticks with high hemoglobin levels (mean hemog lobin = 0.15 mg per pool). A group of nymphs that ingested a mean of 0 .13 mg of hemoglobin contained the same amount of virus (mean viral ti ter almost-equal-to 10(2.5) PFU) as a group of nymphs that ingested 0. 32 mg of hemoglobin. Some adult ticks that ingested <0.35 mg of hemogl obin contained more virus than adults that ingested >4.7 mg of hemoglo bin.