Washington: Scientists have discovered what they say is the oldest ever record of insect pollination after finding dinosaur-age insects with hundreds of pollen grains in tree resins that date back to more than 100 million years.
An international team of scientists studying two pieces of tree resin, or amber, discovered several specimens of tiny insects called thrips with hundreds of pollen grains attached to their tiny bodies.
The insects, which are just two millimetre long and date back between 110 million and 105 million years ago, belong to a new genus now named Gymnopollisthrips, with two new species, G. Minor and G. Major, the researchers said.
"This is the oldest direct evidence for pollination, and the only one from the age of the dinosaurs," study researcher Carmen Soriano, from European Synchrotron Radiation Facility (ESRF) in France, was quoted as saying by LiveScience.
"The co-evolution of flowering plants and insects, thanks to pollination, is a great evolutionary success story."
Pollination occurs when the wind or insects deliver pollen from a plant`s male reproductive organ to the female parts either on the same plant or another one.
During the lower Cretaceous Period when the newly found thrips lived, flowering plants would have just started to diversify, eventually replacing conifers as the dominant species, the researchers said.
The researchers, who detailed their findings in journal Proceedings of the National Academy of Sciences, looked at the amber pieces` discovered in Spain.
They used synchrotron X-ray tomography focusing on the most representative of the amber-encapsulated thrips to get a closer look at the pollination event frozen in time.
In synchrotron X-ray tomography, charged particles are sent speeding through magnetic fields; these particles release high-energy light that can then pierce opaque materials to reveal three-dimensional, high-resolution images.
The images showed various features of the pollen grains, together suggesting the grains came from a kind of cycad, or gingko, tree, the researchers said.
The researchers wondered what these pollen transporters would`ve gotten in return for their services so long ago.
The benefit must have been the opportunity to pick up pollen food for the thrips` larvae, said the researchers, adding that this benefit would have nudged the emergence of the ringed hairs specialised for pollen transport.
"Thrips might indeed turn out to be one of the first pollinator groups in geological history, long before evolution turned some of them into flower pollinators," Soriano said.