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Spiders can track the scent of killer ants to avoid them

Spiders can sniff out killer ants to avoid building webs near them, according to a new study led by Andreas Fischer at Simon Fraser University. By identifying the chemicals produced by European fire ants that deter spiders, experts may ultimately develop natural repellents for homeowners.

“Widespread arachnophobia is fueled, in part, by fear of the few neurotoxic spiders,” explained the study authors. “This fear has inspired the development of tactics to physically and chemically discourage synanthropic spiders from settling in and around human dwellings.”

Many killer ants prey on spiders, and the researchers theorized that spiders instinctively know to avoid locations frequented by foraging ants. 

To test their theory, the experts exposed filter paper to several species of ants and placed it in a multi-chambered habitat containing four different species of spiders. Filter papers without ant semiochemicals were placed in one of the chambers to determine which area the spiders would prefer.

European fire ants are known to be aggressive scavengers that prey on many invertebrates. The study showed that all of the spiders clearly avoided the chemical deposits of these killer ants. They stayed in the chamber that was free of chemicals.

Given how much time and energy spiders put into building their webs, Fischer said it makes sense that spiders in the wild would pick locations that have fewer threats to their survival.

Many insecticides and other chemical products claim to repel spiders, but most have proven largely ineffective. This is because spiders can simply abandon their webs and rebuild nearby. 

Harnessing the chemicals produced by their natural predators could help create more effective repellents. 

“Once identified, the origin of these deterrents could be traced to a specific exocrine gland and/or the body surface of ants,” wrote the study authors. “Moreover, synthetic replica of these deterrents could be developed, together with concurrently known spider deterrents, for earth-friendly manipulation of synanthropic spiders.”

The study is published in the journal Royal Society Open Science.

By Chrissy Sexton, Staff Writer

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