Action spectra for prevention or termination of diapause in three species of Lepidoptera

Action spectra for photoperiodic induction or termination of diapause in three species of Lepidoptera were determined by synchronizing the appropriate stage in an LD 16:8 regimen in which a 12-hr day of CW fluorescent light was extended by 6 hr of spectral light. A combination of full- and half- silvered mirrors were used to direct the spectral light, which passed through appropriate combinations of interference filters onto each of the three groups of insects in each test conducted. The action spectra for prevention of diapause in larvae of the European corn borer and the pink bollworm exhibited maxima lying between 420 and 490 nm. The action spectrum for termination of diapause in pupae of the so-called oak silkworm, Antheraea pernyi Guérin Ménèville, was extended from previous work to below 420 nm, with a maximum of about 410-480 nm. These action spectra are consistent with absorption spectra obtained from the brains of the same insects. Results are not inconsistent with the hypothesis that a heme-enzyme-substrate complex is one potential photoreceptor for pigment in the diapause response.