It’s the small things that matter – when insects shaped today’s natural world

A fossil carnivorous wasp from the McAbee locality in southern British Columbia, Canada.

Paleontologist Bruce Archibald at the McAbee fossil site near Cache Creek in southern British Columbia. The fossil beds are exposed on the hills behind him. 

Ants originated long before this large fossil species from the Okanagan Highlands deposits of British Columbia, Canada, but only began diversifying to their modern ecological importance around the time that this ant lived, after the extinction of the dinosaurs. 

A fossil carnivorous wasp from the town of Republic, Washington, USA.

January 16, 2018

Insects that play an essential role in moulding ecosystems may have begun their rise to prominence earlier than previously thought, shedding new light on how the world became modern. That is the finding of a new paper published by an international team of researchers led by Simon Fraser University's Bruce Archibald who is also a research associate at the Royal BC Museum.

The team of collaborators from Canada, Russia, and South Africa examined insect fossils of the roughly fifty-million-year-old Okanagan Highlands fossil deposits in southern British Columbia, Canada and northern Washington, USA.

Archibald says, “These fossil sites preserve animals and plants of upland forests, lakes, and swamps a dozen or so million years after the extinction of the dinosaurs, as the modern world was beginning to emerge.”

The team found that while ants, bees and ecologically important groups of carnivorous and herbivorous wasps originated long before Okanagan Highlands time, they appear to have remained minor elements of ecosystems until a burst of diversification first appears in the fossil record around fifty million years ago. This was previously thought to have mostly happened in younger times.

The team reports that the diversification of these insect groups represents the onset of a major phase in insect evolution, not by the appearance of important new kinds, but by a great expansion of the species and numbers of individuals of previously existing kinds.

These insects have been tremendously successful, saturating ecosystems with great numbers of individuals, assuming a wide range of roles as pollinators, carnivores feeding upon the insects that in turn feed upon plants, and as consumers of plants themselves.

Archibald says that these insects are key to shaping and maintaining our planet’s ecosystems today. He points out that bees are critical for their essential role as pollinators, while carnivorous wasps consume large numbers of plant-eating insects such as caterpillars. They are essential in regulating plant-eating insect populations and establishing patterns of plant diversity and ecosystem stability. He adds, “Ants are abundant worldwide with a few exceptions, and are efficient foragers that strongly influence the numbers and kinds of plants and invertebrate that live in natural communities.”

This study was published in The Canadian Entomologist.