A natural alternative to pesticides may be hiding in a misunderstood plant compound — but it could come at an environmental cost.  

For years, scientists knew little about isoprene, a natural chemical produced by plants. New Michigan State University research 40 years in the making now sheds light on how this natural chemical can repel insects — and how some plants that don’t normally make isoprene could activate production in times of stress. 

Tom Sharkey, a University Distinguished Professor in the Michigan State University-Department of Energy Plant Research Laboratory, the MSU Plant Resilience Institute and Department of Biochemistry and Molecular Biology, has studied isoprene for much of his career. Now, his lab has published findings that could provide a path for engineering plants that are more resilient to environmental change and pest outbreaks. 

The team’s paper in Science Advances uncovers a hormonal response triggered by isoprene that makes insects steer clear of those plants. Insects that munched on isoprene-treated leaves got a stomachache, thanks to indigestible proteins that kick in when the compound is present. Those proteins also stunt the growth of worms that dare to keep eating them.