What is the effect of pesticides on worm growth?

Question

As a new semester begins, we were asked to propose ideas for investigatory projects. Our idea revolves around the effects of pesticides on non-target organisms. Since frequent use of pesticides may potentially affect the health of the soil, we chose the earthworms as our target organism. Our experimental set-up was revolves around studying their growth. Two containers (Container A-Control, Container B-Experimental) would be filled with soil and other things that are essential for worms to live. In container A, normal soil would be used. On container B, we would spray pesticide on the soil and mix them so that it really gets in the soil. After that, we would place the worms (5 each container). The allotted time for data gathering and analysis is 3 weeks. Given this situation, we would observe the behavior of the worm each day for 10 to 14 days (depending on our schedule) and their growth on the last day by measuring their length, weight, and describing their color. I think that our set-up is logical instead of finding farms that sprayed pesticide for the last 20 or so years which is difficult in our situation. Does anyone have any feedback on the particulars of the experiment based on previous research on the subject?

Answer 1

This is an extremely interesting question! Many research studies have reported the negative impact of pesticides on the soil and environment, and their direct influence on humans as we consume produce exposed to pesticides. Therefore, organisms inhabiting the soil would be the most affected as the American Chemical Society has confirmed in a 30-day study comparing worms in a pesticide-environment (experimental group) compared to the control environment where the worms had no exposure to pesticides. The results were drastic, revealing that the worms in the single pesticide-treated soil gained 30 to 80% less weight that the worms living in the untreated soil, and the treated-soil worms had increased mtDNA damage. The findings point towards a link between pesticide use and earthworm health which raises the questions what further damages would be found if the 30-day period was extended.