What is the key characteristic that differentiates releaser pheromones from primer pheromones?

Releaser pheromones are characterized by their rapid effects on behavior, which is why the correct choice is that they are fast acting. These pheromones trigger immediate responses in receivers, such as changes in behavior, including mating, foraging, or alarm responses. For example, when a queen bee releases pheromones during mating, they quickly attract drones to her. This immediacy is essential in their role within the colony, as it facilitates interactions that are critical for the survival and functioning of the hive.

In contrast, primer pheromones operate more subtly and gradually, influencing developmental and physiological changes over a longer-term period rather than eliciting instant reactions. They may regulate processes such as reproduction or social structure in the colony, working to establish or maintain those dynamics over time, which differentiates them fundamentally from releaser pheromones.