Symposium: New Technologies for the Taxonomic Identification of Arthropods: Comparisons of Cat Flea (Sphonaptera: Pulicidae) Adult and Larval Insecticide Susceptibility

  • Laila M. El-Gazzar
  • R. S. Patterson
  • P. G. Koehler


The resistance levels of a Florida strain of cat fleas, Ctenocephalides felis (Bouche), were evaluated using nine chemicals after colonization for approximately one (1984) and two (1985) years. It was found that the fleas had lost some of their resistance to chlorpyrifos and malathion in 1985 compared to 1984. Moreover, higher resistance was detected to the three carbamates, bendiocarb, propoxur, and carbaryl. The increased carbamate resistance was attributed to the use of carbaryl dust to kill the fleas on cats after they were taken out of flea production. The resistance levels for propetamphos, diazinon, isofenphos and chlorfenvinphos did not change significantly. Comparing the 24 h toxicity of the nine compounds against larval and adult stages in 1985, chlorpyrifos, diazinon, chlorfenvinphos, and propoxur were more toxic to adults than larvae and propetamphos, malathion, and bendiocarb were more toxic to larvae than adults. The tolerance to isofenphos was similar for larvae and adults. Both stages responded equally to carbaryl and were completely resistant. All organophosphates in 1985 exhibited delayed larval mortalities and affected cocoon formation of the larvae that survived the 24 h exposure. However, none of the organophosphates, or the carbamates, appeared to have any effect on adult emergence indicating that the delayed toxicity does not extend beyond larval stage.
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