Antscan Catalogs a Digital Library for Ant Biodiversity

Ants, whether they’re scavenging for crumbs in a kitchen pantry or ambling along a dirt path, are aplenty. In nature, there are thousands of ant species with scientists having identified roughly 15,000 species so far.¹ Museums and research laboratories house only a small fraction of ant species. These specimens vary widely in size and shape, reflecting the diverse adaptations ants have evolved across the globe.

To better study this diversity, entomologist Evan Economo, who is now at the University of Maryland, has been using micro-computed tomography (micro-CT), a technique similar to medical CT scans, to create high-resolution 3D images of both the internal and external structures of ants. “We can extract interesting traits from the specimens to really understand how different aspects of their anatomy adapt to different challenges and has evolved over time,” explained Economo.

However, the process faces a major bottleneck: Scanning a single ant specimen on a standard laboratory scanner can take between 10 and 15 hours. Sharing and accessing these datasets at scale is also difficult; full 3D morphologies are available from museums, but they are not always easily accessible. In 2019, when Economo led a research group at Okinawa Institute of Science and Technology, he and collaborators began asking a broader question: What if researchers could access a massive, digitized collection of ant specimens without needing to track down physical samples in museums? Instead, scientists could simply search an online database and immediately use the scans for their own research. This vision led to the development of Antscan, an open-science initiative aimed at building a large-scale digital library of ant biodiversity.²

Instead of a laboratory scanner, Economo’s collaborators at Karlsruhe Institute of Technology (KIT) had a better solution—an X-ray micro-CT scanning powered by a synchrotron particle accelerator. This imaging technique creates a much more concentrated flux of X-rays and greatly improves throughput: The difference was staggering. Economo said, “You can scan a specimen in 30 seconds with a similar quality to what would take 10 hours.”

In 2020, Economo’s team began collecting ant samples. Julian Katzke, then a graduate student in Economo’s group said, “To be as sure as possible that we have the best-preserved specimens, we decided to partner up with all these local and regional biodiversity stakeholders—especially professors and museums.” However, COVID-19 threw a wrench in this plan.

While they still managed to coordinate specimens from some museums and university collections, “A lot of institutions like museums closed and we really tapped into hobbyists and collectors around the world who may not be professionals,” explained Economo.

The team reached out to these networks worldwide, from hobbyists in Spain and the Iberian Peninsula to an ant aficionado and high school student in Korea, through social media. The team received the majority of their samples in the mail. From there, they prepped the ants in ethanol and packed them to be analyzed at KIT.

There, the team scanned more than 2,000 specimens (from 212 genera and 792 species) over the course of one week. Of these, the collection included queens, workers, and male ants. “Males are often difficult to come by, so we had some of our collaborators make a dedicated effort to contribute male ants,” said Katzke.

They generated massive amounts of morphological data which revealed ants’ exoskeleton, but also internal soft tissues. The 3D models are interactable, enabling users to rotate, zoom, and virtually dissect the insects to learn more. For instance, researchers used this data to ascertain how certain ant species structure their colonies by favoring quantity over the quality when investing in an ant’s exoskeleton.³ By skimping out on this protective armor, ants could save on nutritional resources to produce more workers.

Katzke, now a postdoctoral research fellow at the Smithsonian National Museum of Natural History, added that the work is ongoing. The team has already entered 1,000 Australian ant scans. Also, because the researchers can sample multiple populations of the same species, “We are really focused on getting the same species from different localities,” Katzke explained, in hopes of identifying climate-related adaptations and traits that make ants more vulnerable.

Since the database is publicly available, the team hopes the scans will serve as a valuable resource for researchers, supporting efforts to integrate phenotypic and genomic data while also providing a workflow model for developing similar libraries for other organisms.

“One of the things that's most exciting to me is,” added Economo, “in addition to people like us who want to study ants and the evolution of species, once the specimens get into the digital realm they can go to a lot of different [audiences and applications].” These models can then be used by artists, sculptors, 3D animators, and educators, who might not have access to these resources otherwise. Katzke emphasized, “We're hoping that the biodiversity of ants will just become immediate and more understood in greater society.”

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