Dopamine mediates the pea aphid wing plasticity

Many organisms exhibit phenotypic plasticity, in which developmental processes result in different phenotypes depending on their environmental context. We focus on the molecular mechanisms underlying that environmental response. Pea aphids (Acyrthosiphon pisum) show a wing dimorphism, in which pea aphid mothers produce winged or wingless daughters when exposed to a crowded or low-density environment, respectively. We investigated the role of dopamine in mediating this wing plasticity, motivated by a previous study that found higher dopamine titers in wingless- versus winged-producing aphid mothers. In this study, we found that manipulating dopamine levels in aphid mothers affected the number of winged offspring they produced. Specifically, asexual female adults injected with a dopamine agonist produced a lower percentage of winged offspring, while asexual females injected with a dopamine antagonist produced a higher percentage of winged offspring, matching expectations based on the titer difference. We also found that genes involved in dopamine synthesis, degradation, and signaling were not differentially expressed between wingless- and winged-producing aphids. This result indicates that titer regulation happens in a non-transcriptional manner or that we sampled non-relevant timepoints or tissue. Overall, our work emphasizes that dopamine is an important component of how organisms process information about their environments.