Reproductive success of cat fleas, Ctenocephalides felis, on calves as unusual hosts

Cat fleas, Ctenocephalides felis, were released onto calves as unusual hosts, and sampled at intervals for histological examination. Egg output from fleas on age-matched male and female calves was monitored. Using indicators of reproductive maturation and regression together with egg output data, the reproductive success and fertility of cat fleas on male and female calves were estimated. Comparisons were made with fleas taken from cats. The mean egg output of fleas on the bull calf was highly significantly different from that on the age-matched female calf: 28.14 +/- 2.96 (SE) eggs/h compared with 16.21 +/- 1.96 (SE) eggs/h. A higher proportion of sampled fleas (83.0%) was reproductively mature on the feline hosts compared with the calves (45.4-62.5%). Blue bodies resulting from oocyte resorption were present in the ovarioles of 10.4-19.0% of fleas sampled from the calves. No blue bodies were present in fleas removed from cats. Eggs laid by fleas on calves were viable and larvae were reared to adulthood. The mean percentage hatching success on the age-matched male and female calves was 46.7% and 51.7%. This represents a reduction in viability of 28-33% compared with eggs laid by fleas on cats. Factors which may account for reduced reproductive maturation of fleas on calves, including protein content of the host's blood, are discussed.