Plants may seem defenseless against insects, having neither hands nor tails to brush them away. But many produce potent repellent chemicals, ranging from ones that just taste or smell bad to ones that can kill.

These disgusting compounds work well against nibbling and sap-sucking insects that feed on a wide range of plant types, as well as grazing and browsing mammals. Yet inevitably, over the course of evolution, certain animals specialized to the point that they’re now attracted to even the most repulsive stuff that plants have come up with. In fact, many of the crops our own species grow for consumption, from tobacco to to get rid of crop pests has contributed to drastic declines in insect populations. Might these pesticides have reduced the numbers of natural enemies available to help us control crop pests, and do you think there is a way to bring them back?

Yes. In Switzerland, there are efforts to have flower strips alongside cropping fields, , an independent journalistic endeavor from Annual Reviews. Sign up for the newsletter.

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