In the Andrade lab at the University of Toronto, a cricket hurls itself to the floor in a desperate bid to escape certain death. Life Sciences student Humza Raza frowns, scoops it up, and rips off its legs before tossing it to an Australian redback, one of the deadliest widow spiders in the world. The redback will make quick work of liquefying the cricket's innards, leaving a desiccated husk.
The genus Latrodectus contains some 30 species, all with neurotoxic venom. A single bite can lead to nausea, difficulty breathing, fever, cramping, and in extreme cases, death. Professor Maydianne Andrade's Integrative Behavioural Ecology of Mating lab contains thousands of the iconic black widow spiders, making it one of the deadliest insect labs in Canada.
Studying these species, with their often perplexing and counter-intuitive behaviour, is crucial in understanding how evolution works, and how sexual selection can influence evolution. "It can allow us to understand underlying theory that can be applied anywhere," says Andrade. "Because it's not just the weird sex lives of spiders. This might be telling us something in general about how the world works."
The lab investigates all aspects of arachnid reproductive behaviour—from how tendencies toward boldness and voraciousness influence sex selection to maternal protectiveness (the female black widow will occasionally engage in a tug-of-war with researchers as they try to remove her egg sac). The U of T researchers have been getting loads of attention lately for their work studying how male black widows mate with hungry females, who tend to be more than a little bit cannibalistic during copulation. A recently published paper in Animal Behavior documented the role that pheromones play in prompting the males mate with hungry females, despite this risk of cannibalization.
When Andrade initially set up her behavioural research lab in 2000, she says reactions were more negative than if they had been studying radiation. People were afraid that the spiders would be just hanging all over the room or escaping into the building, which goes back to a general visceral fear of spiders. "People think they're sentient," she says of the notorious spiders. "They think that they're coming after them." Protests didn't die down until they realized how careful Andrade was (and it helps that custodial staff don't have to clean the cages).
Thanks to diligent adherence to protocol, Andrade hasn't had any bites (although nearby hospitals are aware that the lab exists, and have access to the antivenom). She has a strict zero-tolerance policy for any silk or webs outside of testing containers, and any escapees are immediately reported and destroyed. Students wear latex gloves and dentist-style lab coats with closed cuffs. "The real risk is an established population in the building. So we vacuum the rooms every week, even though we don't see anything—if they suddenly have black widows in the stairwell, they're gonna know where they came from."
That's especially true if the black widows are sexed-up cannibal females.
Many widows are cannibalistic; a redback male will often catapult himself into the female's mouth during copulation. This extreme sexual sacrifice will ensure at least some of his sperm makes it through the door. Males vying for female favour will also "dance" for hours, vibrating on the web in a dizzying show of endurance. If they fail to appease her, they too are lunch. In this alternate reality, females have all the power.
Andrade notes the lengths the males will go to copulate. They are smaller and less resilient than females, and just locating her web is an ordeal. Ironically, their eyesight isn't the best—they have eight (shitty) eyes—so they rely heavily on pheromones which they "taste" through receptors in their legs. A male will climb to a high point and wave his forearms, ostensibly sampling the air to get a whiff of a female.
"When the male detects the pheromone, not only does he start courting—which involves bouncing on the web—he also tries to reduce the likelihood that other males will find that female, and he does that by cutting up the silk, balling it up, and wrapping his own silk around it. Sometimes it's so much that the female is trapped in one corner, with her web destroyed."
"And she doesn't just eat him?"
"Females seem to tolerate it from males who they want to have mate with them."
"Because the males have two copulatory organs—he inseminates each organ in two separate copulations." The redbacks will approach the female once, she'll start to eat him, then he gets off, courts her again, and goes back a second time—to finish (and be finished off). "If you don't court long enough, she will kill you after one mating. And then she's more likely to mate with a rival."
In one experiment room, Andrade pulls a plastic tupperware box from a stack on the shelf, lifting the mesh lid. I cringe, eyeing the female hovering on her makeshift web inside. This one's plump (the lab receives 1,500 crickets each week to feed them) but most can survive up to six months without eating. "Which is why they're invasive," says Andrade. "They can get stuck in a box and shipped somewhere, and even if it's months later, they can start reproducing immediately." They often hitch a ride here in grape packages from California.
The lab has started looking into how web disruption reveals individual spider personalities; for example, some take longer than others to come out of retreat after their web has been jostled. Andrade points to the pink sex toys in the experiment room. "We have vibrators, as ways of stimulating the web. This is actually a really good way of creating regular, predictable stimuli. It's hooked up to some electronics, that allow us to trigger it a particular time or particular duration, and we can measure the actual vibrations produced. We've had some pretty funny encounters with personal stimulatory devices." This repeatable stimuli can be used to assess whether the spiders respond with repeatable behaviours.
Andrade's research led her to spider-watching in western Australia, often laying underneath webs in the middle of the night, alone, with no light save for a single red headlamp. At one point, after laying for hours under a web, she felt a sharp pinch to her shoulder. For about half an hour she panicked until she determined it was just a splinter. But even that wasn't enough to put her off. It was the males of her own species that gave her pause.
"I'm also a rare phenotype—there's not a lot of black people there—a woman out at night by herself," she remembers. "There was more than one occasion that I actually pulled my bike over and hid in the bushes when a car went by."
The spiders "were never my concern. I was more afraid of the humans."
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