Fig. 8. Daily variation of the male B. mori's behavior to different concentrations of artificial pheromone. Period during which the light was turned off is indicated by a gray bar along the x-axis. The N values for each group varied between 41 and 88. Around noon (10.00 h and 12.00 h),moths showed highest sensitivity to pheromone, significantly higher than during scotophase (GLM, P<0.05). The daily behavioral response to pheromone was strongly correlated to the daily variation of serotonin in the moth's brain (Fig. 7) (Pearson correlation coefficient: >0.90 for 0.1 ng, 0.5 ng and 1 ng).