INSECT SPECIES RICHNESS TRACKING PLANT-SPECIES RICHNESS IN A DIVERSE FLORA - GALL-INSECTS IN THE CAPE FLORISTIC REGION, SOUTH-AFRICA

The Cape Floristic Region(CFR) is one of the most plant-species-rich r egions in the world. It is also a warm temperate region and hypothetic ally should have high gall-insect species richness, making it interest ing to investigate the relationship between the insects of the region and the rich flora. The relationship between gall-insect species richn ess (GSR) and plant richness was investigated for the Fynbos and for r epresentatives of vegetation of the whole CFR. Samples (of up to 600 p lants per transect for Fynbos) of woody shrubs were investigated for t he presence of galls. The species richness of these insects was quanti fied, as well as plant species richness for each transect. GSR for Fyn bos was compared to global figures for GSR. Fynbos harboured significa ntly more gall-insect species than other CFR vegetation types. GSR was positively correlated with CFR plant richness. GSR also closely track ed plant richness in Fynbos. GSR was not significantly influenced by o ther variables (elevation and aspect), suggesting that plant richness per se was an important factor in generating GSR. Fynbos GSR is compar able to other sclerophyllous regions of high GSR globally, corroborati ng that this vegetation type is conducive to gall-insect diversificati on. There is likely to be a high percentage of gall-insect endemism in the Fynbos, as might be expected from the high host fidelity of this insect group.