Structural reactions to polarized light of microvilli in photoreceptor cells of the moth Spodoptera.

Intact armyworm moths (Spodoptera exempta, Fam. Noctuidae) were illuminated by polarized monochromatic light to induce structural changes in the rhabdomeres of the compound eyes. The degree of distortion of their microvilli depends on the light energy absorbed per time unit. Under polarized light, the number of quanta absorbed varies with the position of the plane of polarization relative to the axis of the microvilli (intrinsic dichroism). Therefore, in Spodoptera, different degrees of deformations could be demonstrated in differently oriented rhabdomeres of both types of ommatidia. Moreover, in rhabdoms of the lobed type with fan-like arranged microvilli, different reactions were regularly seen in differently oriented microvilli of one rhabdomere. This indicates that microvilli may react to light individually.