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Pesticides might be helpful for crops but their effect on earthworms living in the soil under the plants is devastating, according to a new study. The worms in such conditions only grow to half their normal weight and become incapable of reproduction. 

"We see that the worms have developed methods to detoxify themselves, so that they can live in soil sprayed with fungicide. They spend a lot of energy on detoxifying, and that comes with a cost: The worms do not reach the same size as other worms, and we see that there are fewer of them in sprayed soil. An explanation could be that they are less successful at reproducing, because they spend their energy on ridding themselves of the pesticide," said researchers, Ph. D. student Nicolas Givaudan and associate professor, Claudia Wiegand, in the press release.

Researchers set up an experiment to study the behavior of the earthworm species Aporectodea caliginosa. They observed how the fungicide-exposed worms adopted to the toxic environment. They added that over the generation worms have developed a method to detoxify themselves. 

Researchers also noted that there were 2-3 times more earthworms in unsprayed soil than in sprayed soil. 

"The fungicide increased metabolism rate in the worms, both the adapted worms and the not adapted worms. In the not adapted worms we saw that their energy reserve of glycogen was used faster. Contrastingly, only in the adapted worms we saw that amino acids and protein contents increased, suggesting a detoxification mechanism. They also increased their feeding activity, possibly to compensate for the increase in energy demand," researchers added.

The research was conducted by a Danish/French research team and will be published in Soil Biology and Biochemistry.