Fossilised beetle poo sheds light on prehistoric pollinator diets

14 Apr 2021

Ecological reconstruction of a prehistoric beetle pollinating flowers. Image: Jie Sun

Researchers have used a beetle fossilised in amber to learn more about prehistoric pollinator-flower systems.

A new study claims that some ancient pollinators didn’t just transport pollen, but fed on it too. Researchers at the University of Bristol and the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences have unearthed new findings using a prehistoric pollinator fossil.

Pollinators are some of the most important organisms on Earth. They carry pollen from one flowering plant to another, servicing more than 180,000 plant species and more than 1,200 crops.

It’s believed that pollinators evolved after the first flowering plants began to diversify during the Cretaceous period, which took place between 145m and 65m years ago. However, there has so far been limited fossil evidence of Cretaceous pollinators.

Using an amber fossil of a beetle from this period, Pelretes vivificus, researchers have now found that its faecal matter was made up entirely of pollen. Their findings have been published in Nature Plants.

A prehistoric pollinator

Pelretes vivificus, a flower beetle, lived in the Burmese amber rainforest around 98m years ago. Its closest relatives alive today can be found in Australia, where they visit a diverse range of flowers and feed on their pollen.

One of the palaeontologists involved in the research, Prof Chenyang Cai, said that Pelretes vivificus is associated with clusters of pollen grains, suggesting that short-winged flower beetles visited angiosperms, or flowering plants, during the Cretaceous period. Its hairy abdomen and other anatomical features are adaptations associated with pollination.

Top-down view of the prehistoric pollinator flower beetle used in this study.

Image: Chenyang Cai, Yanzhe Fu and Yitong Su, Lingzi Zhou

“The pollen associated with the beetle can be assigned to the fossil genus Tricolpopollenites. This group is attributed to the eudicots, a living group of angiosperms that includes the orders Malpighiales and Ericales,” added fossil pollen specialist Dr Liqin Li.

According to Li, this suggests that pollinators interacted with early flowering plants soon after they initially diversified and by the mid-Cretaceous were visiting a diverse range of groups.

Erik Tihelka, entomologist and palaeontologist at University of Bristol’s School of Earth Sciences, added: “The fossil faecal pellets are completely composed of pollen, the same type that is found in clusters surrounding the beetle and attached to its body.

“We thus know that Pelretes visited angiosperms to feed on their pollen. This finding provides a direct link between early flowering plants in the Cretaceous and their insect visitors. It shows that these insect fossils were not just incidentally co-preserved with pollen, but that there was a genuine biological association between the two.”

Lisa Ardill was careers editor at Silicon Republic until June 2021