Insect flower visitors, foraging behaviour and their effectiveness as pollinators of Persoonia virgata R. Br. (Proteaceae)

Abstract

Leioproctus species are frequent flower visitors to Proteaceae and have been inferred as pollinators of many species of Persoonia. This study investigated frequency of flower visitors, their behaviour and the breeding system of Persoonia virgata. The two most frequent visitors were the native bees Trigona carbonaria Smith (Hymenoptera: Apidae) and females of Leioproctus (Cladocerapis) speculiferus Cockerell (Hymenoptera: Colletidae). These species have different foraging strategies on the flowers of P. virgata and, on the basis of more frequent stigma contact, L. speculiferus was found to be the most effective pollinator. Pollination studies indicated that fruit set of bagged flowers (0.5% and 9.2%) was significantly less (P < 0.001) than fruit set of control flowers left open to visitors (24.0% and 48.9%) in two experiments, respectively. Furthermore, flowers that were bagged and cross-pollinated set significantly (P < 0.001) more fruit (43.8%) than flowers that were bagged and self-pollinated (6.6%), suggesting partial self-incompatibility. No significant difference in fruit set was found between control flowers and cross-pollinated flowers, indicating that flower visitors of P. virgata were efficient vectors of cross-pollen from plant to plant.