How does a microbrain generate adaptive behavior?

Insects have evolved a diversity of sophisticated behaviors through natural selection. Controlling such behavior exclusively relies on their nervous system, especially the brain. Insects have rather a small number of constituent neurons in the so-called microbrain. Insects will become an excellent model for understanding adaptive control in biological systems which will inspire control and communication in engineered systems. We demonstrate a behavioral model based on the neural basis for controlling the odor (pheromone)-source searching behavior in insects. Under changeable circumstances insects orient toward the odor source by repeating the set and reset of the odor-triggered programmed behavioral pattern interacting with the odor distribution status in the air. The behavioral threshold to the odor is dynamically changing moment by moment depending on their internal and external conditions, and experiences encountering the odors, which will play an important role for generating adaptive behavior.