Effect of temperature and the synergist piperonyl butoxide on imidacloprid toxicity to the cat flea (Siphonaptera: Pulicidae).

Abstract

The toxicity of imidacloprid to cat fleas on glass was investigated at 20, 26, 30, and 35 degrees C. Imidacloprid was most toxic to adult cat fleas at 35 degrees C and to larvae at 20 degrees C. Piperonyl butoxide (PBO), a synergist, increased the relative potency of imidacloprid (1:5 imidacloprid:PBO) 16-fold at 26 degrees C against adults, but had no effect at 35 degrees C. No synergism occurred in larvae at 20 degrees C, but addition of PBO (1:5 imidacloprid:PBO) doubled toxicity at 26 degrees C. PBO (1:5 imidacloprid:PBO) could possibly be used to synergize imidacloprid premise treatments (20-30 degrees C), but it is not likely to be effective in pet treatments because no synergism occurred in adult fleas at 35 degrees C (average fur temperature of tested cats and dogs).