Brett Smith for redOrbit.com – Your Universe Online
For years, the military has used radio signals to jam an enemy’s radar and a new study in the journal Biology Letters suggests hawk moths use the same technique to evade predation by bats.
According to the study’s authors from the University of Florida, hawk moths emit sonic pulses from their genitals in response to the high-frequency echolocation that bats produce to locate prey.
“This is just the first step toward understanding a really interesting system,” said study co-author Akito Kawahara, assistant curator of Lepidoptera at the Florida Museum of Natural History.
“Echolocation research has been focused on porpoises, whales and dolphins,” he continued. “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.”
Hawk moths are a favorite insect among researchers and particularly geneticists due to their large size. The study was conducted in Malaysia, which holds the highest level of diversity for hawk moths anywhere in the world.
Previous studies have shown tiger moths use ultrasound as a defense mechanism. However, tiger moths use a vibrating membrane on the thorax to produce the sound, while hawk moths emit the sound from their genitals.
Kawahara said the hawk moths may use the sound to warn others or to jam bats’ echolocation system, disrupting the predators’ ability to identify and hone in on an object.
“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,” Kawahara said. “The fascinating part is that there are a lot of new discoveries to be made. It’s a totally unknown, unexplored system.”
Using high-energy lamps to capture the hawk moths in the jungle, the research team played pre-recorded bat sounds to the insects and captured the sounds the hawk moths made in response. They found at least three different hawk moth species produce the sound, including both males and females.
“As a museum, we are creating a library of life,” Kawahara said. “Museum specimens are usually preserved immediately, but we are trying to understand the behavior of these organisms so that we have a record of their behavior along with the specimen and DNA. This is why there are so many interesting things we’re starting to discover.”
In addition to providing more information about a particular species, echolocation research could also translate into improvements in ultrasound medical technology, the researchers suggested.
The team said they plan to continue researching the hawk moths’ ultrasound capabilities with an emphasis on determining the evolution of this defense mechanism.
“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,” Kawahara said. “Hawkmoths have evolved different ways of avoiding bats – I can’t even explain how amazing the system is, it is just fascinating.”
With more than 1,400 species worldwide, hawk moths are some of the fastest and most proficient flying insects. They are also considered to be important pollinators, with many plants dependent solely on hawk moths for reproduction.
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