Flower-visiting and mating behaviour of Eulonchus sapphirinus (Diptera: Acroceridae)

Abstract

AbstractAcrocerid flies are often considered to be rare and their role in pollination is poorly understood. In this study, adult Eulonchus sapphirinus Osten Sacken were common on flowers of Geranium robertianum L. (Geraniaceae) in Olympic National Park, Washington, and have morphological and behavioural characteristics that indicate a dependence on floral nectar. Both males and females of this species are good potential pollinators from a behavioural standpoint. They make few revisits to individual flowers, remain highly constant to one flowering species in each nectar-foraging bout, and carry pollen on their bodies. Individuals were abundant and formed the majority of insect visitors to G. robertianum flowers. Males and females differed in their flower-visiting behaviour, with females visiting more individual flowers and doing so more slowly than males. This difference between the sexes appears to relate to mating behaviour, which takes place within the flower patches. The ramifications of the observed flower-visiting and mating behaviour for flower pollination are discussed. This study shows that based on both their abundance and their behaviour, these flies are potentially important pollinators in certain habitats.