Insect perception of ambient ultraviolet-B radiation

Solar ultraviolet-B radiation (UV-B, 290-315 nm) has a strong influence on the interactions between plants and animal consumers. Field studies in various ecosystems have shown that the intensity of insect herbivory increases when the UV-B spectral band of solar radiation is experimentally attenuated using filters. This effect of UV-B on insect herbivory has been attributed to UV-B-induced changes in the characteristics of plant tissues, and to direct damaging effects of UV-B photons on the animals. We tested for effects of UV-B radiation on insect behaviour using field experiments with the thrips Caliothrips phaseoli. When placed in a 'choice' tunnel under natural daylight, these insects showed a clear preference for low-UV-B environments, and this preference could not be accounted for by differences between environments in total irradiance. These results provide the first evidence of ambient UV-B photoperception in an insect, challenging the idea that animals are unable to detect variations in the narrow UV-B component of solar radiation.