BREAKDOWN OF POLLINATOR SPECIFICITY IN AN AFRICAN FIG TREE

A single giant-leafed fig tree (Ficus lutea) is planted on the Rhodes University campus in Grahamstown, South Africa, some 500 km outside its normal distribution range. Small numbers of fig wasps (Hymenoptera, Agaonidae) which normally pollinate two other Ficus species entered and successfully pollinated the figs of this tree. One of the wasp species reproduced successfully. Monitoring of adult fig wasps arriving at the tree established that these alien species were not attracted to F. lutea. However, from laboratory studies it appears that once having landed on F. lutea figs, these wasps were stimulated to search for the ostiole, through which they gained entrance to the fig cavity. Females of a third pollinator species were also present on the tree, but they failed to initiate ostiole searching behavior when on the figs. Hybrid seeds resulting from the entry of the alien wasps germinated successfully, but did not progress past the cotyledon stage, indicating postgermination deficiencies in the hybrids.