Whether by buzzing, singing, cawing or hissing, plenty of animals boast their own form of communication. But researchers now hope to unlock a common predator-prey language found in insects and mammals: echolocation in hawkmoths and bats.
“Moths and bats are completely unrelated yet they are talking to each other,” said principal investigator Akito Kawahara, assistant curator of Lepidoptera at the Florida Museum of Natural History. “We can’t hear it, but they certainly can, so we’re trying to do some experiments where we let the two organisms fly together and see how they interact.”
The National Science Foundation recently awarded Kawahara $260,000 to research hawkmoths’ use of echolocation as a defense mechanism against predatory bats. The grant will fund research in Ecuador, French Guinea and Borneo, molecular biology lab work at the Florida Museum, and experiments at a live bat cage in Boise, Idaho, run by co-principal investigator Jesse Barber, an assistant professor of biological sciences at Boise State University.
“There isn’t much work like this done on insects, and it has mostly focused on grasshoppers and crickets communicating with each other,” Kawahara said. “Right now, we have a really confusing ball of information – we have to try to untangle it and determine the many communication mechanisms within the group.”
Previous research shows other moths use sonar defense against bat predators by “jamming” the bats’ echolocation with a sound that confuses them. Based on the fossil record, interaction between moths and bats dates back at least 50 million years and researchers hope to understand how their coexistence may have affected their evolution, including the development of ears in hawkmoths, which are found in their mouths. Hawkmoths make sounds using their genitals and another aspect of the project will address preliminary evidence they use this form of communication in mating.
“We don’t really understand when and how sound production and the ability to hear arose in hawkmoths, but it looks like one led to the other and we don’t know which came first,” Kawahara said.
Hawkmoths are among the fastest and most proficient flying insects. Unlike butterflies, which land on a flower to drink nectar, some hawkmoths hover in midair, similar to hummingbirds. They have wingspans that can reach 6 inches and a curled proboscis, or tongue, up to 10 inches long.
“We’re not only trying to understand the evolution of sound production and hearing, but also the evolution of nectar feeding,” said Kawahara, who will primarily focus on the molecular biology research for the project. “By using genetics, we can build an evolutionary tree to see when and how these things have happened.”
More than 1,000 species of hawkmoths occur worldwide, with the highest diversity in tropical and sub-tropical regions. Researchers will introduce hawkmoths to live bat cages and use devices to measure the different echolocation frequencies and document patterns in as many species as possible. High-speed video cameras will create 3-D reconstructions of confrontations and Kawahara said he also hopes to use the footage for educational and outreach purposes in the future.
“There’s a lot of really interesting stuff going on at night,” Kawahara said. “It’s just like a battle out there – bats versus moths – we just don’t know much about it because it happens in the dark and we can’t hear it.”
Learn more about the McGuire Center for Lepidoptera & Biodiversity at the Florida Museum.