The role of dopamine signaling in olfactory associative learning and memory in the oriental fruit fly, Bactrocera dorsalis

Associative learning is central to studies of cognitive behavior in invertebrates, including insects. It involves acquiring new values from rewards and punishments by continuously updating sensory cues. Different biogenic amines guide the processes of reward and punishment. The role of dopamine (DA) signaling in associative learning has long been a focal point in the study of insect cognition. Previous studies across multiple insect species have established a general framework in which DA is primarily associated with aversive learning and punishment processing. However, emerging evidence suggests that DA has also been implicated in appetitive memory in certain species, indicating potential variability in the neuromodulatory mechanisms underlying associative learning. Here, we conducted behavioral assays, pharmacological interventions, and molecular manipulations to investigate the role of DA signaling in both aversive and appetitive classical conditioning in Bactrocera dorsalis , an economically important agricultural pest with well-documented learning and memory capabilities. We found that pharmacological blockade of DA signaling impaired aversive but not appetitive learning and memory, consistent with its conserved role in punishment processing. RNAi knockdown of DA receptors impaired both aversive learning and memory, reinforcing the pharmacological findings. Surprisingly, BdDOP2 knockdown impaired appetitive memory, uncovering a unique role for DA receptor subtype in appetitive memory. These findings provide new insights into the conserved and divergent functions of DA in insect cognition. Our results highlight B. dorsalis as a promising model for studying the neural mechanisms underlying associative learning, with potential applications in developing targeted pest control strategies by disrupting specific aminergic pathways involved in olfactory-based decision-making.