Circadian Rhythms in the Mantis, Sphodromantis lineola

There are approximately 2300 described species of praying mantis within the taxon Mantodea. These  ‘charismatic’, predatory insects occupy a broad range of widely distributed habitats, showing remarkable diversity in morphology, hunting strategies, and habitat specialization. No previous studies have examined whether circadian rhythms play a role in any aspect of mantid behavior or physiology. However, it is well known a visual-system mediated circadian pacemaker modulates the behaviors of various cockroaches (Blattodea), the sister taxon to the Mantodea. We pursued two lines of research to assess the possible role of circadian rhythms in one species of mantis: 1) long term videography to analyze patterns in gross locomotor activity, fluctuations in compound eye pigmentation, and circadian changes in mantis responses to visual stimuli; 2) anatomical and histological analyzes of brain structure to determine the presence of GABA-ergic accessory medulary neurons similar to those responsible for circadian rhythms in the Blattodea. We hypothesize that both predatory and locomotor behaviors are controlled by a circadian mechanism localized to the accessory medulla in the mantis optic lobes. Preliminary data suggest several temporal peaks in behavior occurring just before subjective dawn and dusk. This cycle may underpin the biochemical and behavioral parameters that create times of  peak efficiency predatory-related behaviors.