Regional differences in photoreceptor structures in the compound eye of the stinkbug, Plautia crossota stali

Abstract

We investigated the regional structural characteristics of the compound eye of the stinkbug, Plautia crossota stali, in order to elucidate their functional significance for visual orientation. Towards the frontal end of the eye's equatorial line, we found some special structural features: smaller inter-ommatidial angles, indicating high acuity; and longer rhabdoms, suggesting high sensitivity compared to other regions of the eye. When the bug is flying towards a light source, it orients itself such that the target is always captured by this specialized region. These anatomical and behavioral studies both indicate that the bug exhibits marked regional specialization of the retina. In the dorsal region of the eye, there is another special ommatidial structure: untwisted, orthogonally oriented microvilli, which suggests evector discrimination ability. These findings are the first reported examples of regional specializations in the eye of a heteropteran species, and may reflect ecological features of its habitat.