Contradictory field results on pesticide effects on honeybees are explained using a systems biology approach. The study focuses on system architecture rather than individual interaction strengths. In vivo experiments on caged honeybees demonstrate that pesticide impact is shaped by concurrent stressors. The immune-suppressive effect of deformed wing virus (DWV) creates a positive feedback loop, leading to bistability (two stable equilibria). This explains how bees under similar conditions experience different outcomes (prolonged survival or premature death) when exposed to the same stressor, impacting hive vulnerability. These conclusions reconcile conflicting field test results and have implications for field studies on complex systems.

Dimitri Breda, Davide Frizzera, Giulia Giordano, Elisa Seffin, Virginia Zanni, Desiderato Annoscia, Christopher J. Topping, Franco Blanchini, Francesco Nazzi