Abstract

The order Diptera is the second most important group of pollinators worldwide. Many flies are considered generalist pollinators, but specialist flower flies’ associations are rare or uncommon. The present study aimed to determine the level of specialization in pollination for Aneriophora aureorufa (Philippi, 1865) (Diptera: Syrphidae), an endemic species of the South American temperate forests. The study evaluates also the species abundance in different sampling sites and environments. Our data suggest that Aneriophora aureorufa has an exclusive and extremely narrow association with the flowers of Eucryphia cordifolia Cav.¸ an endemic Chilean species. We reviewed the literature on Chilean pollinator species searching for information about Aneriophora Stuardo & Cortés 1952 and compared its exclusive association with other specialist flies. We conducted long-term fieldwork for 22 years in one location during the flowering season and over a period of one to six years in five additional locations. In our field study we recorded all insects which had contact with stigma and/or stamens of 25 plant species. We found that Aneriophora visits flowers of E. cordifolia in both low absolute abundance and low relative percentage, and occasionally visits flowers of two other species. In the northern distributional range of A. aureorufa, where E. cordifolia is absent, the hoverfly was recorded in flowers of Laurelia sempervirens (Ruiz & Pav.) Tul. (Chilean laurel, Atherospermataceae), but in low frequency (0.01 flowers/min). In a site where we have a long-term study, A. aureorufa represented only 0.2% of all flower visitors, and its abundance was higher in canopy forests, visiting 0.03 flowers/min. Based on our observations and the literature review we propose that (1) Aneriophora is one of the most specialized pollinator flies described until now; (2) the species is more frequent in old-growth forests than in forest edges or isolated trees.