Figure 8.

Derivation of the absorbance spectrum of the filter pigment in type II ommatidia of male P. rapae crucivora. a, The absorption spectrum of a visual pigment (rhodopsin) R425 and the spectral sensitivity of the dB photoreceptors (Fig. 6b). b, The difference between the common logarithm of the spectra of a yields the absorbance spectrum (absdif) of the filter pigment. The dashed curve is calculated with the lognormal function of Metzler et al. (1985), with a peak absorbance of 0.58, a peak wavelength of 416 nm, a skewness of 1.7, and a half-bandwidth of 60 nm (lognorm).