Stony Brook University Stony Brook, New York, United States
Abstract: Growers devote vast global acreage to genetically modified soy crops. Because earthworms provide a suite of ecosystem services, we have a critical need to understand the impact of genetically modified plants on them. Our experiments aimed to address earthworm responses to living with genetically modified and heirloom soy plants. We grew soybeans and earthworms together in mesocosms and measured: a) earthworm body mass, b) mesocosm water use, and c) soybean biomass. Earthworms living with heirloom soybeans (N = 41) weighed an average of 0.30 + 0.13 g when the plants reached the third trifoliate stage while earthworms living with genetically modified seeds (N = 37) weighed 0.24 + 0.11 g. Earthworm survivorship did not vary with plant type. Living with genetically modified plants caused a 20.0% decrease in earthworm body mass relative to worms living with heirloom plants. While genetically modified plants used 15.2% more water than did heirloom plants, and heirloom plants grew taller and heavier than genetically modified plants, neither of those parameters drove earthworm body mass. We suspect that changes in soil microbiome drive changes in earthworm biomass and have a suite of experiments lined up to test that hypothesis. In summary, genetically modified soybeans can potentially impact adversely earthworm populations by reducing individual body mass.
