The oldest known insects engaged in pollination were discovered while studying amber obtained from Cretaceous-era deposits, by an international team of paleontologists.
We the humans have a keen sense of curiosity, which always urges us to know more. It could be a place near our neighborhood or deep down in the ocean beds. For paleontologists, they spend time digging around in the dirt, trying to find the world's past. Most of the time, you'd think that these history finders dig up artifacts of a lost world that when put together, amass big creatures, villages and more. But this time what they unearthed, were of equal prominence but not as big as the others.
The 105-million to 110-million-year-old thysanopterans that were unearthed were coated in pollen grains that were presumably used to feed the insects' offspring.
Thysanopterans, commonly called thrips, are tiny, slender insects with fringed wings -- hence the name, from the Greek thysanos (fringed) and pteron (wing). Thrips are generally considered pests because they eat plant tissues, but some are efficient pollinators for several species of flowering plants.
The role of thrips in the pollination are highly synchronized. Phenology of flowering with the life cycle of thrips, modification of flowers to facilitate pollen transfer by thrips and definite pattern of host succession that help maintain the population of thrips are reported. These features represent strategies in plants favouring a strong association between the thrips and the plants. Pollination is the process by which pollen is transferred in the reproduction of plants, thereby enabling fertilization and sexual reproduction.
Amber samples containing the insects were obtained from a site in the Basque-Cantabrian Basin of northern Spain, a team headed by paleontologist Enrique Penalver of the Instituto Geologico y Minero de Espana in Madrid, reported in the Proceedings of the National Academy of Sciences. They imaged the insects using the synchrotron at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. The images revealed two new species of thrips, which they named Gymnospollisthrips major and G. minor.
The thrips had hundreds of pollen grains stuck to their bodies. The exterior of the insects had highly specialized hairs with a ringed structure to increase their ability to collect pollen grains, very similar to those of contemporary pollinators like bees.
The small pollen grains are believed to come from a cycad or ginkgo tree. Ginkgos are either male or female, and males produce pollen that must be transported to the female tree by wind or insects. The researchers speculated that the thrips established colonies in the female trees and carried pollen from the male trees to feed their offspring.
"Thrips might turn out to be one of the first pollinator groups in geological history," said paleontologist Carmen Soriano of ESRF.