Pollen-Feeding Flies Pollinated Flowers 47 Million Years Ago
Hirmoneura messelense, a newly described species of nemestrinid fly that lived approximately 47.5 million years ago (Eocene Epoch), pollinated flowers of at least two plant genera.
“Bees, bumblebees, and butterflies are widely known pollinators of flowering plants who, to some degree, also feed on pollen,” said Dr. Sonja Wedmann, a researcher at the Senckenberg Research Institute and the Natural History Museum in Frankfurt.
“Yet, it is often ignored that flies also play an important role in this regard. Our latest research results show that dipterans fed on pollen as long as approximately 50 million years ago!”
Dr. Wedmann and her colleagues analyzed the contents of the conspicuously swollen abdomen of Hirmoneura messelense, which was discovered at the famous Messel Pit paleontological site near Darmstadt in Germany.
They found pollen grains from at least four plant families: Lythraceae, Vitaceae, Sapotaceae, and Oleaceae; mainly from two extant plant genera: Decodon (water willows) and Parthenocissus (Virginia creepers).
“This is the first indication that flies from the family Nemestrinidae fed on pollen in the past — and possibly continue to do so until today,” Dr. Wedmann said.
“Such fossil food remnants are extremely rare on a global scale,” she added.
“They allow inferences as to the animals’ lifestyle and feeding behavior as well as the environmental conditions under which the animals lived at the time.”
The large volume of Parthenocissus pollen supports the hypothesis that Hirmoneura messelense fed on plants that grew along the edge of an ancient forest and the Messel lake.
“The flies undoubtedly avoided long-distance flights between their food plants to save energy,” Dr. Wedmann said.
“We therefore assume that the plants associated with the pollen could be found within a relatively small area.”
“We assume that the flies played an important role in transporting the pollen, and thus in the propagation of several plant families,” she concluded.
“It is possible that flies were — and still are — more important than bees for the pollination of tropical plants.”
The findings were published in the journal Current Biology.
Sonja Wedmann et al. The last meal of an Eocene pollen-feeding fly. Current Biology, published online March 10, 2021; doi: 10.1016/j.cub.2021.02.025