Flies and flowers: taxonomic diversity of anthophiles and pollinators

The Diptera are the second most important order among flower-visiting (anth ophilous) and flower-pollinating insects worldwide. Their taxonomic diversi ty ranges from Nematocera to Brachycera, including most families within the suborders. Especially important are Syrphidae, Bombyliidae, and Muscoidea. Other families, especially of small flies, are less appreciated and often overlooked for their associations with flowers. We have compiled records of their flower visitations to show that they may be more prevalent than usua lly thought. Our knowledge of anthophilous Diptera needs to be enhanced by future research concerning (i) the significance of nocturnal Nematocera and acalypterate muscoids as pollinators, (ii) the extent to which the relativ ely ineffective pollen-carrying ability of some taxa can be compensated by the abundance of individuals, and (iii) the role of Diptera as pollinators of the first flowering plants (Angiospermae) by using phylogenetic and pala eontological evidence. Specializations in floral relationships involve the morphology of Diptera, especially of their mouthparts, nutritional requirem ents, and behaviour, as well as concomitant floral attributes. The South Af rican flora has the most highly specialized relations with dipterous pollin ators, but in arctic and alpine generalist fly-newer relations are importan t in pollination and fly nutrition.