Abstract: Circularly polarized light is rare in the terrestrial environment, and cuticular reflection from scarab beetles is one of the few natural sources. The scarab beetle Anomala corpulenta Motschulsky possesses a brilliant metallic appearance, and selectively reflects left circularly polarized light as other jewel beetles. To clarify the capacity of responses of A. corpulenta to circularly polarized light, indoor behavior, field selection and electroretinogram (ERG) responses of A. corpulenta to circularly polarized light were studied in this experiment. The indoor behavior research showed that the phototaxis responses of A. corpulenta to left and right circularly polarized light were significantly lower than those to unpolarized light, while the photophobism responses were significantly greater than the phototaxis responses to unpolarized light, and both the phototaxis and photophobism responses of A. corpulenta to left circularly polarized were greater than those to right circularly polarized light. The field selection test results showed that the selection of A. corpulenta to left and right circularly polarized light was obviously lower than that to unpolarized light, and the responses selecting to right circularly polarized light were stronger than that to left circularly polarized light. Electrophysiological studies showed that left and right circularly polarized could trigger ERG responses of A. corpulenta compound eyes as unpolarized light, and had no obvious difference among them. These results indicate that A. corpulenta is a metallic iridescent species that selectively reflects left circularly polarized light and possesses a brilliant metallic appearance. It can perceive and distinguish left and right circularly polarized light, and circularly polarized light can trigger ERG responses of A. corpulenta compound eyes as unpolarized light. These results support the hypothesis that A. corpulenta has polarization vision and sensitivity to circularly polarized light.

Key words:  Anomala corpulenta, circularly polarization light, polarization vision, phototactic behavior, electroretinogram (ERG)