Attraction to water and polarization in dragonflies and damselflies along a light pollution gradient.

Aquatic insects, like odonates, rely on polarized light as a visual cue to locate water bodies for reproduction. However, artificial polarization from light pollution can lead them into ecological traps. This study investigates odonate preference for polarized light cues compared with other sensory cues associated with water perception, and the effects of exposure to artificial polarization on their sensitivity to these cues. This study tests whether artificial polarization imposes a selective pressure that modifies odonate behavior and sensitivity to water and polarization signals. We predicted that odonate species in areas with higher light pollution would show a reduced preference for anthropogenic polarizing traps and an increased preference for natural water bodies. Our multiple-choice experiment revealed interspecific differences in cue attraction, with some species preferring polarizing traps while others favored water or color cues. Species attracted to the ecological light traps were always a subset of the total species present in each locality, indicating that most species are not attracted to ecological traps. Surprisingly, we found few significant differences in odonate behavior between polarization exposure categories, suggesting either weak selective pressure, prioritization of other sensory cues, or existing physiological-behavioral strategies that allowed them to avoid these ecological traps. We observed sex disparities in susceptibility to all experimental surfaces, with males showing greater attraction, potentially due to differences in habitat selection criteria. While evidence of strong selective pressure from light pollution is lacking, a reduction in light pollution near water bodies is needed to conserve odonates and aquatic insect populations.