Behavioural role of individual components of a multichemical attractant system in the Oriental fruit moth

IN most moths, location of the female for mating is mediated by pheromones¹, which are operationally defined as attractants, although their ability to elicit upwind orientation has been demonstrated in only a few species². Intrinsically unattractive chemicals which modify this process by increasing or decreasing trap catch have been termed synergists and inhibitors¹, respectively, although their behavioural and neurophysiological roles have remained unresolved. In the Oriental fruit moth, Grapholitha molesta (Busck), cis-8-dodecenyl acetate (c8-12:Ac) is a primary pheromone component³ and recently the requirement for attractancy of an isomeric mixture containing about 8% trans (t8-12:Ac) was demonstrated ^4,5. Additionally, male trap catch has been reported to be enhanced about two fold by the simultaneous release of dodecyl alcohol (12:OH) (ref. 5). Specific behavioural functions, however, had not been ascribed to individual attractant components or combinations.