Not so sweet after all: are candy-striped spiders a threat to ecosystems across North America

For years, pollinator declines have been a pressing issue for ecosystem health and food security in the face of climate change and human impacts on the environment. Even in their sleep, pollinating insects cannot catch a break – for fear they’ll be taken down by a small, but mighty predator: the candy-striped spider. Research published in Ecology took a closer look into this spider’s behaviour and found that the result of their stealth attacks could have substantial impacts on ecosystems.

Most likely accidentally introduced to both the East and West Coasts a little over a century ago, the candy-striped spider is a very common spider in North America. The spider’s striking colour varieties have attracted much research into their genetics, but before now very little was known about their behaviour.

“This common spider previously flew under the radar of researchers in North America and almost nothing was known about its diet and behavior”, explains Catherine Scott, a Postdoctoral Fellow in McGill’s Department of Natural Resource Sciences and co-author of the study. “We documented their diet and predation behaviour in the field and learned that they use a variety of tactics to take down prey much larger than themselves, including sleeping bees and wasps.”

While these spiders may have negative effects on pollinators, they may have positive effects of preying on insects that are pests of agricultural crops. In terms of next steps, the researchers will investigate candy-striped spiders in food webs of agro-ecosystems in southern Quebec. “At a time where the world is facing a biodiversity crisis that includes unprecedented declines of insect pollinators, future studies will help determine whether their benefits as natural pest-controllers outweigh their negative impacts as predators of pollinators “says Scott.

About the study

They mostly come at night: Predation on sleeping insects by introduced candy-striped spiders in North America” by Catherine E. Scott and Sean McCann was published in Ecology.

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