ARE ODORANT-BINDING PROTEINS INVOLVED IN ODORANT DISCRIMINATION

Pheromone-sensitive sensilla trichodea of nine moth species belonging to six families and three superfamilies of Lepidoptera were immunolabe lled with an antiserum against the pheromone-binding protein of Anther aea polyphemus. Strong immunolabelling of the sensillum lymph was obse rved in all long sensilla trichodea of A. polyphemus, A. pernyi (Satur niidae), Bombyx mori (Bombycidae) and Manduca sexta (Sphingidae). Very weak labelling was found with all sensilla trichodea of Dendrolimus k ikuchii (Lasiocampidae) and Lymantria dispar (Lymantriidae). In three noctuid species, some long sensilla trichodea were labelled strongly, some only weakly and some were not labelled at all. The fraction of lo ng sensilla trichodea that were strongly labelled was large in Helicov erpa armigera, but small in Spodoptera littoralis and Autographa gamma . The observed cross-reactivity was not correlated with taxonomic rela tedness of the species but rather with chemical relatedness of the phe romones used by these species, as a high labelling density was consist ently observed in sensilla tuned to pheromones with an alcyl chain of 16 carbon atoms. The highly divergent specificity of pheromone-recepto r cells in Noctuidae appears to be mirrored by a similar diversity of the pheromone-binding proteins in the sensilla trichodea. These data s upport the notion that pheromone-binding proteins participate in odora nt discrimination.