The effect of melatonin on locomotion and circadian rhythm of Camponotus floridanus

Melatonin is a hormone responsible for regulating an organism’s biological clock located in their brain and exogenous melatonin can alter their sleep-wake cycle. Previous studies conducted on invertebrates found that exogenous melatonin impairs their locomotion (Yamano et al., 2001). However, the effect of melatonin on invertebrate species, specifically ants, has been rarely explored. We aimed to study the relationship between melatonin and ant locomotion and the role melatonin plays in ant circadian rhythm. We administered melatonin, ramelteon, a melatonin agonist, and luzindole, a melatonin antagonist, to different groups of Camponotus floridanus to explore the impact of exogenous melatonin on ants. We found that exogenous melatonin decreased the locomotion of ants by decreasing the ants’ velocity and total distance traveled. The administration of melatonin also impacted the ants’ circadian rhythm by making them more lethargic throughout a 24-hour cycle. Surprisingly, ramelteon, a vertebrate melatonin agonist, had the opposite effect. These results suggest that the use of exogenous melatonin hinders ants on an individual and societal level.