Nectar concentrations of biogenic amines affect bumble bee behavior in a dose-dependent manner

While foraging, pollinators encounter a wide array of molecules, some of which may influence their internal states and behaviors. Among these, biogenic amines - nitrogenous compounds that serve as essential neuromodulators in animals - have only recently been detected in floral nectar. As a result, little is known about the effects of nectar concentrations of these compounds on pollinators. In this study, we tested how two key biogenic amines, octopamine and its precursor tyramine, affect bumble bee behavior by examining: 1) consumption and survival, 2) locomotion, and 3) feeding behavior. Our findings show a preference for low concentration of octopamine (0.1 mM) and a dose-dependent effect on flight behavior. Specifically, a concentration equal to 0.1 mM of octopamine reduces the bee's motivation to fly, whereas a concentration of 1 mM increases flight duration. Tyramine has no significant effect on any of the behaviors tested. Our results demonstrate that nectar-borne biogenic amines have the potential to influence various bumble bee behaviors critical to flower visitation.