Light attraction of the Indian meal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), and regional spectral sensitivity of its compound eye

I tested the hypothesis that the Indian meal moth, Plodia interpunctella(Hübner), uses wavelengths of visible blue/violet light as orientation cues. In four-choice laboratory experiments, blue light (400–475 nm) was significantly more effective than green (475–600 nm), orange (575–700 nm) or red (590–800 nm) light in attracting males and mated females. The 405-nm “violet” light emitting diode (LED) was significantly more effective than the 435-, 450- or 470-nm “blue” LED in attracting males as well as virgin and mated females. A 405-nm wavelength also significantly enhanced the known attractiveness of UV light. In electroretinograms, standardized responses of dorsal, equatorial and ventral eye regions to UV, violet and green light were similar, but the equatorial region was most sensitive. Occluding regions of the eye did not affect the moths’ behavioural orientation to violet light, indicating that phototactic responses are not dependent on a single eye region.