Population structure and insecticide response of Gammarus spp. in agricultural and upstream forested sites of small streams

Abstract Exposure to pesticides may cause adaptation not only in agricultural pests and pathogens, but also non-target organisms. Previous studies mainly searched for adaptations organisms pesticide-polluted sites. However, propagate heritable pesticide effects, such as increased tolerance, non-exposed populations through gene flow. We examined the tolerance—as one of pre-assumptions local adaptation—of freshwater crustacean Gammarus spp. (at genus level reflecting gammarid community). The tolerance was quantified acute toxicity tests using insecticide imidacloprid. Gammarids were sampled at sites (termed agriculture), least impacted upstream refuge) transitional edge) six small streams south-west Germany. Furthermore, we population genetic structure fossarum energy reserves (here lipid content) G. well three site types (i.e. agriculture, edge refuge). found significantly lower imidacloprid from compared refuge sites, potentially due higher environmental stress indicated by a slightly content per mg tissue. no differences between populations, indicating propagation effects edges. among showed significant differentiation streams, within stream across types. suggest that high flow each hindered resulted similar (pre)adaptations levels types, although they exhibited different pollution. Further on target genes (e.g., conferring tolerance), fitness phenotypes particular are required adjacent pristine ecosystems detect potential propagations effects.