According to a study published July 3, 2013 in an online version of the journal Royal Society of Biology Letters, Boise State University researcher and study co-author Jesse R. Barber, and Akito Y. Kawahara, assistant curator of Lepidoptera at the Florida Museum of Natural History, University of Florida, found that hawkmoths deter bats by emitting a so-called “anti-bat ultrasound.” The emission of ultrasonic pulses from the genitals of the hawkmoths essentially jams the bats’ most precious hunting technique: echolocation.
Although hawkmoths are major pollinators, some are major agricultural pests, but researchers routinely utilize the Hawkmoth for beneficial genetic research. Only the Hawkmoth and the Tiger moth are known to have demonstrated ultrasonic emission capabilities.
According to study co-author Akito Y. Kawahara, the discovery is “[J]ust the first step toward understanding a really interesting system…Echolocation research has been focused on porpoises, whales and dolphins. We know some insects produce the sounds, but this discovery in an unrelated animal making ultrasound, potentially to jam the echolocation of bats, is exciting.”
Unlike the Hawkmoth, the tiger moth uses a vibrating, exoskeletal structure called tymbals to produce ultrasonic pulses, whereas the Hawkmoth emits such pulses from its genitals. Scientists have discovered that three hawkmoth species produce ultrasonic pulses, and include both males and females. Scientists also believe that hawkmoths may produce the sound to warn others or to jam the bats’ echolocation capability. This jamming confuses the bats so they may not home in on a potential meal or interpret its location.
Malaysia has the highest diversity of hawkmoths in the entire world, so Kawahara sought out and received a National Science Foundation grant of approximately $500,000 to fund his research. In addition, Kawahara conducted research in the jungles of Borneo and the lower Amazon River.
Commenting on his research, Kawahara said, “So much work has been focused on animals that are active during the day, but there are a lot of really interesting things happening at night, and we just don’t know a lot about what is actually going on — because we can’t hear or see it…The fascinating part is that there are a lot of new discoveries to be made. It’s a totally unknown, unexplored system.”
Commenting on the probable reason behind the use of ultrasonic emissions in hawkmoths, Kawahara said, “We think hawkmoths are a primary food source for bats because none appear to be chemically defended, which is why they have evolved anti-bat ultrasound strategies…hawkmoths have evolved different ways of avoiding bats — I can’t even explain how amazing the system is, it is just fascinating.”