Scientists have discovered a 47 million-year-old fossil fly with a swollen abdomen completely filled with pollination grains.
This discovery is the first direct evidence that some ancient, cross-vein species once fed the delicate spaces of many different species of subtropical plants.
“The rich pollen content that we discovered in the fly’s stomach indicates that the flies were already feeding and transporting pollen from 47 million years ago, and it appears to have played an important role in the spread of pollen grains to many plant varieties,” says botanist Friedger Grimsson of the University of Vienna. .
And when most people think of a pollinator, they imagine a bird, a bee, or a butterfly.
Today, cross-vein flies with short, tongue-like structures known as cannulae have been completely overlooked as potential carriers of pollen grains. In fact, only modern nemostrinids with long sucking appendages were observed feeding on tubular plants, and even then, only on nectar.
The new fossil, found in an abandoned quarry near Frankfurt, Germany, represents a new species of ancient short-barrel fly (Hirmoneura messelense) that appeared to have had a great appetite for pollen.
Researchers believe that this pollinating insect may once have outpaced bees.
Fossil records reveal that direct pollen feeding is extremely rare, but the last meal of this fly has been remarkably preserved. Under a microscope, her intestines and stomach show traces of pollen from at least four plant species, including water willow and virgin ivy, which may have grown around the margins of an ancient lake forest.
Researchers can also see the long hairs – also known as a bundle of hairs – on the fly’s chest or abdomen. While pollen grains were not found on these hairs, the fact that these long hairs are present indicates that they can transfer pollen as well as the fly moves from flower to flower.
In fact, the fly’s proboscis is so short that it is not even visible. Researchers believe it may be hidden inside the insect’s head.
The flowers they seem to feed on are usually packed tightly together, allowing the insect to move between them easily – and eat one meal after the other.
Three unknown types of pollen in the fly’s stomach also indicate that it feeds on a mixture of parent plants that have grown in close proximity.
It is possible that the fly avoided long flights between food sources, and sought to obtain pollen from plants closely related to it, “according to Grimson.
While modern flies that visit flowers are not as effective at transmitting pollen as bees, they make up for it through the sheer numbers. The investigation into these pollinators has long been neglected, and studies are few and far between.
This new discovery supports an old hypothesis that in some modern tropical environments, flies that visit flowers may be at least as important as some pollinating bees – and maybe more. And the fact that pollen was discovered in the stomach of an ancient fly says that this may have been an important role for the insect since the Jurassic times.
“The cross-vein fossil fly clearly feeds on angiosperm pollen grains, and thus represents the first direct evidence of a pollen-eating nemestrinide,” the researchers concluded.
The study was published in a journal Current Biology.