Sex pheromone evidence for two distinct taxa withinGraphania mutans (Walker)

The sex pheromones of two populations ofGraphania mutans (Walker) were analyzed. Females from an Auckland population produced (Z)-9-tetradecenol (Z9-14∶OH), (Z)-9-tetradecenyl acetate (Z9-14∶OAc), (Z)-7-tetradecenol (Z7-14∶OH) and (Z)-7-tetradecenyl acetate (Z7-14∶OAc), while females from a Lincoln population produced these four compounds and a large amount of (Z)-9-tetradecenal (Z9-14∶Ald). Significant differences, paralleling the difference between females, were observed when the responses of males of both populations to the above and other related compounds were tested by electroantennogram, field-trapping, and wind-tunnel bioassays. The most distinct difference was observed in the wind tunnel. Males from both taxa flew upwind and touched pheromone sources containing sex pheromone extract of females of their own taxon, but either did not initiate upwind flight or arrested upwind flight shortly after taking flight in response to extract from females of the other taxon. The difference between the pheromone systems of the two populations is probably due to the presence and importance of Z9-14∶Ald in the pheromone blend of the Lincoln population. Thus the addition of a relatively large amount of Z9-14∶Aid to a four-component pheromone blend (i.e., Z9-14∶OH, Z9-14∶OAc, Z7-14∶OH, andZ7-14∶OAc) attractive to Auckland males completely suppressed trap catches of male G.Mutans in Auckland but large numbers of males were caught at both Lincoln and Nelson in traps baited with this five-component blend. In wind-tunnel studies, the addition of even small (1% of amount of Z9-14∶OH) amounts ofZ9-14∶Ald to the four-component blend resulted in a significantly greater proportion of Auckland males arresting upwind flight than to the four-com ponent blend. It is suggested that these two populations of G. nations represent distinct sibling species within the described concept.