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Title: ULTRASTRUCTURE OF THE EGG OF THE CAT FLEA

Author
item MARCHIONDO, ALAN - FERMENTA ANIMAL HEALTH CO
item Meola, Shirlee
item MEOLA, ROGER - TEXAS A&M UNIVERSITY
item PALMA, KATHLEEN - TEXAS A&M UNIVERSITY
item SLUSSER, JAMES - VIRGINIA MEDICAL SCHOOL

Submitted to: Proceedings of the International Symposium on Ectoparasites of Pets
Publication Type: Proceedings
Publication Acceptance Date: 6/8/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Fleas are aggravating disease carrying pests that are difficult to manage with conventional insecticides. Three new insecticides (fenoxycarb, methoprene, and pyriproxyfen) with unique modes of action are currently being tested on pets and livestock. These compounds are insect growth regulators that control insects by disrupting development of immature stages. A study of the development of the egg in the female and of the ultrastructure of the egg, provided new information on the mode of action of the insect growth regulators on the immature stages of flea eggs.

Technical Abstract: Methoprene, pyriproxyfen, and fenoxycarb were found to be potent ovicides against the cat flea. Eggs laid by females exposed to pyriproxyfen 24 hours prior to oviposition developed little or no yolk, those exposed to methoprene or fenoxycarb contained developed larvae that could not hatch. Flea eggs exposed to animal fur treated with these compounds for 1 minute also had embryogenesis disrupted. Basically these compounds mimic the action of juvenile hormone, causing deformation and mortality of the developing eggs. Prerequisite to elucidating the modes of action of these insect growth regulators (IGRs), it was first necessary to characterize the development and morphology of siphonapteran eggs. This study revealed that the cat flea egg has developed specialized adaptations in the life cycle of this ectoparasite with respect to host and environment. The cat flea egg is relatively fragile in comparison with other insect eggs, particularly since it is necessary to endure harsh environments when laid outdoors. This study found the chorion of the egg to be only 4 um thick and less ornate externally than other siphonapteran species. The morphological characterizations of successive developmental processes determined in this research will serve as a baseline for the evaluation of various modes of ovicidal activity exhibited by juvenile hormone analogs and other IGRs.