Effect of diet composition on weight gain, sperm transfer, and insemination in the cat flea (Siphonaptera: Pulicidae).

Weight gain by adult cat fleas, Ctenocephalidesfelis (Bouché), was influenced primarily by the concentrations of protein and sodium chloride in the feeding solution. After 48 h of feeding, fleas fed whole blood weighed almost twice as much as fleas fed plasma or hemolyzed blood and 1.25 times as much as fleas fed 0.15 M sodium chloride. When fleas were fed sodium chloride solutions ranging from 0 to 0.5 M, weight gain was greatest on the 0.15- or 0.2-M solutions. Weight gain decreased significantly when fleas were fed plasma, hemolyzed blood or 0.3 or 0.5 M sodium chloride in place of whole blood, but improved when plasma was diluted 100% and when hemolyzed blood was diluted 10% with distilled water. Adenosine-5'-triphosphate did not appear to stimulate weight gain in cat fleas; weight gain was unchanged in fleas fed hemolyzed blood or 0.15 M sodium chloride to which 0.005 M ATP was added. Insemination did not occur in starved fleas or those fed protein-free diets. When fleas were starved or fed distilled water, sodium chloride, or other salt solutions, sperm was transferred from the testes to the vas deferens in 91-94% of males, but no females were inseminated. In contrast, when fleas were fed whole blood, hemolyzed blood, plasma, or bovine serum albumin (3.5 or 7.0 g/deciliter) dissolved in 0.15 M saline, 80, 80, 10, and 10% of the females were inseminated, respectively.

Factors influencing sperm transfer and insemination in cat fleas (Siphonaptera: Pulicidae) fed on an artificial membrane system.

Sperm transfer through the epididymis, a prerequisite for insemination of cat fleas, Ctenocephalides felis (Bouché) was stimulated by exposure of unfed male fleas to juvenile hormone III residues for 3 d at 25 degrees C or exposure of unfed fleas to 37 degrees C for 6 d. Sperm transfer was completed at least three times faster in unfed males held at 37 degrees C than in those held at 25 degrees C. Although percentage sperm transfer in fleas fed water or 0.15 M saline at 37 degrees C was not significantly increased over that of unfed fleas, a significantly greater percentage of blood-fed males completed sperm transfer at 2, 3, and 6 d. At least two factors influenced insemination: exposure of fleas to host body temperature and amount of food consumption. When blood-fed males and females were paired and fed 0.15 M saline, 0% were inseminated at 25 degrees C versus 35% at 37 degrees C. Because percentage insemination did not increase in blood-fed males and females that were paired and fed 0.15 M saline at 37 degrees C for an additional 48 h, continuous bloodfeeding appeared to be required for maximal rates of mating and insemination. Furthermore, no females were inseminated when blood-fed males and females were paired at 37 degrees C and starved. Treatment of unfed fleas with juvenile hormone III did not substitute for bloodfeeding in stimulating mating and insemination; when blood-fed males were paired with JH III-treated females and vice versa and fed 0.15 M saline at 37 degrees C, 0% were inseminated. However, when fleas were fed 0.15 M saline and exposed to 1,250 ppm juvenile hormone III or fed whole blood and exposed to 12.5, 125, or 1,250 ppm juvenile hormone III, percent insemination was significantly increased in comparison to the controls. Therefore, juvenile hormone secretion in blood-fed fleas may regulate mating success indirectly by stimulating sperm transfer.