Insect Foragers on Solanum Flowers in Australia

Eighteen native insect species were found on flowers of 18 Solanum species in a field study in Australia. All of the Solanum species studied are endemic to Australia and about one-half of them are andromonoecious or dioecious. Fifteen of the insect species and 93% of total floral visitors were bees. New records of activity on Solanum flowers in Australia are reported for Braunsapis and Xylocopa (Anthophoridae), Leioproctus (Colletidae), and Trigona (Apidae). Two species each of the pollen-collecting bees Amegilla (Anthrophoridae), Nomia (Halictidae), and Trigona are considered the most significant floral visitors. This consclusion is based on the distribution, abundance, and behavior of the bees, and on the high percentage of Solanum pollen in pollen loads. Amegilla and Nomia extract pollen by “buzzing” it out of its anthers; Trigona species do not. Species of Amegilla are hypothesized to effect interpopulation outcrosses. Trigona species are considered important primarily in self-pollination, and species of Nomia transmit pollen both within and between plants. This pollinator assemblage is postulated to have been associated with the evolution of dioecy in Australian Solanum