Tarsal Contact Chemosensory Hairs of the Large White Butterfly Pieris Brassicae and Their Possible Role in Oviposition Behavior

The study investigated the tarsal contact chemosensory hairs, specifically "B-type" hairs, on the Large White butterfly, Pieris brassicae, and their role in oviposition behavior. These hairs were more numerous in females, particularly on the fifth tarsomere of the forelegs. The fine structure of B-hairs was analyzed using electron microscopy, revealing five receptor cells per hair, with four functioning as contact chemoreceptors and one as a mechanoreceptor. The chemoreceptors responded to mustard oil glucosides, which were identified as specific chemical stimuli for oviposition. Behavioral experiments showed that females did not significantly prefer any particular glucoside among sinigrin, sinalbin, or glucotropaeolin. The study suggested that B-hairs play a crucial role in the oviposition selection behavior of the butterfly.