PhotoMost agricultural producers use pesticides to protect their crops, but Canadian researchers have raised an alarm. At least one of these pesticides in use across North America is taking a heavier than expected toll on bronze jumping spiders.

I know what you might be thinking: so what? Is this somehow a problem?

Researchers at McGill University say it is – a big problem. That's because this insect naturally fills the role that the pesticide is designed to fill.

“Bronze jumping spiders play an important role in orchards and fields, especially at the beginning of the agricultural season, by eating many of the pests like the oblique-banded leafroller, a moth that attacks young plants and fruit,” said Raphaël Royauté, who headed the study team. “Farmers spray insecticides on the plants to get rid of these same pests, and it was thought that it had little significant effect on the spiders’ behaviors. But we now know that this isn’t the case.”

Behavior change

Researchers came to this conclusion after studying the spiders' behavior before and after exposure to Phosmet, a widely used broad spectrum insecticide. A normal spider is active and aggressive, boldly attacking its prey. It's exactly the kind of spider a grower wants in his or her field.

But after exposure to Phosmet, the researchers found individual spiders underwent a personality change. They were more shy and less bold, meaning they weren't nearly as aggressive in going after other damaging insects.

The study points out that not all spiders underwent this personality change, only certain ones did. The authors speculate it could be because some individual spiders were much more sensitive to the insecticide than others.

Interestingly, the researchers also found that male and female spiders were affected differently, neither in a good way.

Less adventuresome

Males exposed to insecticide were able to continue to capture prey as they had before, but “lost” their personality type when exploring their environment. Individual females, on the other hand, were much more affected in their ability to capture prey.

“By looking at the way that insecticides affect individual spider behaviors, rather than averaging out the effects on the spider population as a whole, as is traditionally done in scientific research, we are able to see some significant effects that we might have otherwise missed,” says Chris Buddle, who co-authored the paper. “It means we can measure the effects of insecticides before any effects on the spider population as a whole are detected, and in this case, it’s raising some red flags.”

Phosmet has been the subject of litigation brought by farm workers and environmental groups that tried to limit its uses. In a settlement with the Environmental Protection Agency (EPA), safeguards were put in place and the pesticides was approved for nine uses.

The nine uses include on apples, apricots, highbush blueberries, grapes, nectarines, peaches, pears, plums, and prunes.  

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