Sex pheromone reception in the moth, Mamestra thalassina. Characterization and distribution of two types of olfactory hairs

Abstract

Two types of olfactory hairs were found on the antennae of the moth Mamestra thalassina (Lepidoptera: Noctuidae) by scanning electron microscopy and electrophysiology. Long olfactory hairs are arranged in 4–5 rows over the border of the sensory field of the flagellar segments. These sensilla were sensitive to (Z)-11-hexadecenyl acetate (Z11-16:Ac) and (Z)-11-hexadecenol (Z11-16:OH). Cross adaptation experiments showed that these two compounds are detected by two separate olfactory neurones. A ventro-medial sensillar field is composed of short hairs that respond only to (Z)-11-hexadecenal (Z11-16:Ald). No olfactory neurone specifically tuned to (Z)-7-dodecenyl acetate (Z7-12:Ac), a compound that elicited electroantennogram responses, was found. Z11-16:Ac, Z11-16:OH and Z11-16:Ald were found in hexane extracts from the female pheromone gland. The olfactory neurones specifically involved in the reception of the pheromone components in M. thalassina are housed in different sensillar types. Sensillar types are constant, morphologically identifiable and localized in precise areas at the surface of the antenna. The consequences of this arrangement of receptor cells are discussed.