Article,
Hover flies are efficient pollinators of oilseed rape
OECOLOGIA, 156 (4): 819-823 (2008)
Abstract
Understanding the consequences of declining diversity and abundance of
pollinators for crops and floral biodiversity is a major challenge for
current conservation ecology. However, most studies on this issue focus
on bees, while other invertebrate taxa are largely ignored. We
investigated the pollination efficiency of the globally abundant hover
fly Episyrphus balteatus on the common crop, oilseed rape (Brassica
napus). The study was conducted over a period of 2 consecutive years by
means of enclosure experiments at an agricultural site located in
Central Hesse (Germany). E. balteatus significantly increased both seed
set and yield. This effect was very constant in the 2 years, despite
considerable interannual differences in total seed numbers and seed
mass. It highlights the important role of hover flies as pollinators of
arable crops under varying environmental conditions. In contrast to
bees, the effect of E. balteatus was lower at high pollinator densities
than at low pollinator de
