How bugs get busy
Dr. Rosalind Murray, from the Department of Biology, talks about bug sex in CBC’s Nature of Things documentary.
When we think of sex, self-imposed cannibalism, food gifts, or hovering dusk dances are probably the furthest things on our minds. But bug sex is bizarre, and mere cannibalism hardly scratches the surface of what goes on when arthropods— invertebrates like insects and spiders—reproduce.
Male fruit flies, for instance, enjoy sex—and turn to alcohol if the ladies turn them down. Male redback spiders willingly throw themselves into the female’s open mouth after mating. These are just a few facts you could learn from CBC’s recent Nature of Things episode titled “Bug Sex,” which was released earlier this month, on March 10, 2023. With a tagline declaring, “Broken genitals and cannibalism. Welcome to the weird and wonderful world of how bugs get busy,” the episode promises to be intriguing.
But as fascinating as it might be to watch fruit flies getting frisky, it is even more fascinating when one of the stars of the episode is your very own biology professor, with your teaching assistant making a brief appearance as well. Dr. Rosalind Murray, assistant professor in the University of Toronto Mississauga’s (UTM) Biology Department, appears on the episode to talk about her area of expertise: dance flies.
Dance flies are peculiar in that sex roles are reversed; it is the females who carry the flashy ornaments and “dance” to compete for male attention while the males do the choosing. In an interview with The Medium, Dr. Murray explains, “Even in his earliest books, Darwin noticed that it was the males of species that were ornamented or had weapons,” giving the peacock’s flashy tail and the lion’s mane as wider known examples, while reminding me of the more obscure examples we had covered in BIO318: Animal Behaviour. “But in dance flies, there’s the opposite happening.” According to Dr. Murray, female dance flies swallow air to inflate their abdomens—arranging their legs laterally around them to appear larger—and hover above the ground like little helicopters to attract mates.
However, females should typically never be ornamented. Eggs are energetically costly to produce and given their limited resource pool, females cannot invest in both showy ornaments and offspring. “Yet, in the dance flies, we have evolution—over and over again—of female-specific ornaments,” she points out. “That’s what’s super cool about this system. Females are ornamented in order to gain access to resources so they can mature their eggs and have reproductive success.”
Dr. Murray studied dance flies during her PhD at the University of Stirling in Scotland and continued researching them when she returned to Canada. She got involved with the CBC documentary through dance fly expert and UTM Professor Emeritus Darryl Gwynne, with whom she had worked with in the past. Together, the two took the film crew out to the small island on the Credit River near Dr. Gwynne’s house, which they call “dance fly island.”
“Dance flies only swarm at dusk and dawn,” explains Dr. Murray. “No one wants to go out at dawn in June since that’s like 4:00 am! So, we did it at dusk.” She tells me that there are always a few moments before the swarming during which they just wait for it to start, thinking: will it happen? Is this the night they’re not going to show up? “Then all of a sudden, there’s some signal—perhaps the light gets right, or something happens—and they just lift off looking like little helicopters,” she says, smiling. “It was just what I remembered from my PhD days, thousands of flies lifting off.” The females would fly parallel to the ground, moving slowly since they are inflated, trying to attract mates. The males would go out to the river, Dr. Murray explains, and catch an insect—perhaps a mayfly or a bug—and then approach the females from below bearing this “nuptial gift.”
Since the female dance flies are not hunters, these food offerings are the only way they can access protein. After the male chooses a female, Dr. Murray explains that the dance flies mate in a “flying triplicate,” in which the male and female copulate while the female feeds on the food gift she received.
First-year UTM PhD student, Tolulope Babalola, makes a short appearance in the Bug Sex episode, examining dance fly samples under a microscope. Coming to Canada as an international student from Atlanta, Georgia, she studies dance flies and sexual selection in Dr. Murray’s lab.
“I didn’t feel like I had much to offer them,” Babalola laughs. “But it was really fun to be involved in it, and to see what goes on behind the scenes.” As a biologist, she has always enjoyed nature documentaries but never had any idea what went on when they were made. This, she says, made it all the more interesting to be on the other side and meet the people who work on the films.
Babalola feels like insects don’t get enough time in the spotlight. “A lot of us don’t see insects as animals,” she says. “We just look at them like they’re this separate, gross thing. But there is so much cool stuff people don’t know about insects!” Babalola thinks that watching them in a nature documentary—a format which most of us are familiar with—could help educate people about them.
To learn more, CBC’s Bug Sex episode can be accessed at www.gem.cbc.ca.
Associate Sports & Health Editor (Volume 49) — Radhia is a fourth-year student double majoring in Biology for Health Sciences and Professional Writing and Communication. She has three years of journalistic experience as a writer in Sri Lanka, and served as Associate Editor for Mindwaves (Volume 16). When she's not writing or studying for midterms, Radhia likes long walks, grey-skied rainy days, and reading children's books (her favourites are Neil Gaiman's Coraline and E.B. White's Charlotte's Web).