Hawkmoths have a defense against one of their potential predators, bats, that they use to ward off attacks, which most other insects don’t have: the Boom Boom Boom of their genitals. Three hawkmoth species can deter bats by jamming the echolocation hunting technique by generating ultrasonic pulses from their genitals, 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.
This “anti-bat ultrasound” wards off and deters bats from making hawkmoths their dinner entrees. Using their genitals to produce the ultrasonic pulses is different from how another insect species, the tiger moths, deter bats — they use a vibrating, exoskeletal structure called tymbals to produce ultrasonic pulses, though the affect upon bats is the same — depriving them of a tasty meal.
While some hawkmoths are major pollinators, others are major agricultural pests.
Hawkmoths are routinely utilized by researchers for beneficial genetic research. Of all known species of moths, only the Hawkmoth and the Tiger moth are known to have demonstrated ultrasonic emission capabilities.
In the words of the study’s 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.”
Both male and female hawkmoths are able to produce the ultrasonic blasts, or pulses. The scientists who wrote the study believe that hawkmoths may produce the sound to warn others or to jam the bats’ echolocation capability. The bats become confused by the jamming to the extent that they may not home in on a potential meal or interpret its location correctly
Kawahara has followed the hawkmoth to study it and its unique capiblities around the world. His research has taken him to Malaysia, which has the highest diversity of hawkmoths in the entire world, to the jungles of Borneo, and the lower Amazon River.
All of this globe trekking is expensive, so Kawahara sought out and received a National Science Foundation grant of approximately $500,000 to fund his research.
According to Kawahara:
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.”
The team notes in their study, published recently in the journal Biology Letters, that the fact that the moths produce these sounds with modified genital structures suggests that the sounds might be used in mating behaviors.
Scientists have previously documented male Privet Hawkmoths (Psilogramma menephron) producing shrill sounds while flying near females. The researchers write: “An intriguing possibility is that the ultrasonic ears in hawkmoths might have first evolved for mates, not bats.”
Whether or not the hawkmoths first evolved their ultrasonic Boom Boom Boom pulses for mating or to deter bats doesn’t really matter that much, in the grand scheme of things. As with humans, all’s fair in love and war.
Written by: Douglas Cobb