Eco‐Evolutionary Feedback to a Pesticide Worsens the Impact of a Pesticide Switch in a Pivotal Freshwater Non‐Target Species

ABSTRACT

Pest management often requires the rotation of insecticides, sequentially exposing non‐target populations to different compounds. In a two‐phased experiment, we assessed whether exposure to the pesticide chlorpyrifos induces rapid evolution in the non‐target species Daphnia magna and quantified the response of control and pre‐exposed populations to a second exposure to the same pesticide, another pesticide with the same mode of action (malathion), or a pesticide with another mode of action (deltamethrin). Chlorpyrifos selection induced rapid shifts in genotype composition and reduced genotype richness and strongly influenced population development following the second exposure. Chlorpyrifos‐selected populations outperformed control populations when subsequently exposed to chlorpyrifos and malathion but underperformed when exposed to deltamethrin. Our results highlight an eco‐evolutionary feedback in which rapid adaptive responses to a pesticide worsen the response when exposed to a different type of pesticide in non‐target species, increasing vulnerability to common agricultural practices.