Responses of the pollinating wasp Ceratosolen solmsi marchali to odor variation between two floral stages of Ficus hispida.

During development of figs on Ficus hispida, only the female floral stage is receptive to its pollinator Ceratosolen solmsi marchali. After this stage, the quantity of fig odor decreases. The effects of F. hispida volatiles from receptive figs (figs at the female floral stage, when they are pollinated) and interfloral figs (between the female floral and male floral stages) on their pollinator were studied, together with responses to compounds present in the odor. Odors emitted by both receptive and interfloral figs were attractive to the pollinator. However, wasps preferred the odor of receptive figs to that of interfloral figs even though the quantity of interfloral volatiles increased. Three monoterpenes that included linalool (major constitutent) and two minor compounds limonene and beta-pinene from the receptive fig volatiles were used to test the pollinator responses. The levoisomer and racemic mixtures of linalool were attractive to the pollinator at high doses, but the dextroisomer was neutral. (+/-)-Limonene and (-)-beta-pinene at high doses were even less attractive to the pollinator than clean air and were neutral at low doses, while (R)-(+)-, (S)-(-)-limonene were neutral at all doses. In blend tests, all four mixtures of (+/-)-linalool or (S)-(-)-linalool combined with (+/-)-limonene or (-)-beta-pinene attracted C. solmsi marchali when administered at high doses. (R)-(+)-linalool and (-)-beta-pinene enhanced the attractiveness of (S)-(-)-linalool to the pollinator, while enantiomers of limonene did not. These results suggest that both quality and quantity of fig volatiles regulate C. solmsi marchali response and that quality is the main host-finding and floral stage-distinguishing cue for the pollinator. Synergistic effects of some compounds may play a role in enhancing attractiveness of the active compounds.