Are Insecticides Creating 'Toxic' Slugs?

With a great deal of scrutiny being aimed at common pesticides, researchers are now investigating unconsidered ways that these pest controls could do more harm than good. The latest of this work has revealed that insecticides could actually be increasing "toxic" slug populations in soil.

That's at least according to a study recently published in the Journal of Applied Ecology, which details how the infamous family of insecticides known as neonicotinoids (neonics) have a new consequence that farmers, researchers, and retails never thought to consider.

Neonics have been a hot topic of controversy in the past. In the United States, for instance, mounting scientific evidence has shown that the application of this pesticide to the exterior of seeds leads to harmful chemicals remaining present in plants for years to come, sullying pollen and harming bee populations.

With this revelation, many big name garden retailers have sworn off the pesticide and any plant products, including seedlings, that have been treated with it. The US Fish and Wildlife Service is likewise in the process of phasing out the products and removing plants associated with it from a number of wildlife refuges - a process that won't be complete until 2016.

However, thanks to their wide availability and popularity, "neonicotinoids are the most widely used insecticides in the world," entomologist Margaret Douglas explained in a statement. "Seed applications of neonicotinoids are often viewed as cheap insurance against pest problems, but our results suggest that they can sometimes worsen pest problems and should be used with care."

In a pair of lab and field experiments, researchers from Penn State and the University of South Florida teamed up to test the effectiveness of neonics and see how they affected slugs and other species, which are essential parts of a soil ecosystems.

"In our lab work, we found that slugs were... unaffected by the neonicotinoid insecticides, likely because they are mollusks and not insects," explained Penn State researcher John Tooker. "But the slugs did transmit the insecticide to ground beetles, impairing or killing more than 60 percent of the beetles."

The resulting imbalance between slugs and their predators led to rapid changes in soil health and growing conditions, in which the slugs were left to overpopulate and adversely affect crops.

The result was a wave of "toxic slugs" that not only poisoned other soil-dwellers, but reduced crop densities by 19 percent and yield by five percent.

According to the research team, this does nothing but add to the growing evidence that neonics are the wrong strategy for crops, also supporting a recent EPA report that claims the pesticides have never actually helped our crops.

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