Synergism of the IGRs methoprene and pyriproxyfen against cat fleas

Tuesday, April 5, 2016: 5:06 PM
Mahi Mahi (Pacific Beach Hotel)
Michael K. Rust , Department of Entomology, University of California Riverside, Riverside, CA
Lance Hemsarth , Hartz Mountain Corp., Seacucus, NJ
The IGRs methoprene and pyriproxyfen have played an important role in the controlling cat fleas in both the environment and on the host. The toxicities of methoprene, pyriproxyfen and combinations of both IGRs to cat flea larvae were determined. The LC50 of methoprene and pyriproxyfen was 0.39 and 0.19 ppm, respectively. The LC50’s of combinations of methoprene:pyriproxyfen in ratios of 1:1, 5:1, 10:1, and 20:1 were 0.14, 0.20 0.20, and 0.20 ppm, respectively. The synergism allowed for a reduction in the concentration of methoprene by one-third. The combinations of pyriproxyfen:methoprene greater than 1:1 were not synergistic. Combinations of methoprene:pyriproxyfen may be effective in increasing residual activity and permit lower dosages to applied to pets.