What is the primary role of the Yellow Belly gene when introduced into the Bumblebee morph combination (Pastel Spider Yellowbelly)?

To act as an intensifier by pushing the visual limits through effective ground color brightening

In complex combinations, the Yellow Belly gene acts as a powerful synergistic agent. In the context of a Bumblebee (Pastel Spider Yellowbelly), the Yellow Belly component is essential for introducing intense, clean background color and contributing to the reduction of dark markings inherited from the Spider gene. Its primary physical contribution extends beyond just spotting the belly; it functions as a contrasting agent that significantly brightens the ground color so effectively that it often overrides or interacts strongly with the typical pattern structure delivered by the other genes present, thus pushing the overall visual intensity and saturation to a higher level.