Olfactory Responses of the Adult Screw-worm After Removal of the Antennae, Mouthparts, Tarsi, and Legs1

Abstract

The removal of certain appendages or segments from adult Cochliomyia hominivorax (Coquerel) and subsequent tests of oviposition, response to baited and unbaited traps, and response to screw-worm-infested wounds of sheep showed that the more important olfactory receptors are situated on the antennae and mouthparts. Removal of only 1 appendage did not reduce egg production drastically, but when both the antennae and mouthparts were removed only 21% of the flies laid egg masses (compared with 93% for the controls). Little oviposition occurred when the “antennaless” (lies were separated from the egging medium; also these flies did not discriminate between baited and unbaked traps, nor were they able to locate screw-worm-infested wounds on sheep. Flies having only 1 antenna removed were able to locate baited traps and infested wounds, but not nearly so well as normal flies. Flies with excised mouthparts responded like normal flies to baited and unbaked traps. The precise location of the receptors was not determined, but the results indicate the necessity of using intact specimens for attractant or behavioral studies.