Structure and photoreception mechanism of the compound eye of Bactrocera dorsalis Hendel

Objective To study the external morphology, internal microstructure and photoreception mechanism of compound eye of the oriental fruit fly (Bactrocera dorsalis).

Method The external morphology of compound eye of B. dorsalis adult was observed using a scanning electron microscope. The microstructure of compound eye and the structural change of ommatidia under different monochromatic lights were observed using histological biopsy.

Result The compound eyes were hemispheric, smooth, and located on the lateral upside of head. The gaps among ommatidia were covered with interommatidial hairs. Each ommatidium was comprised of a cornea, a crystalline cone, retinula cells, a rhabdom and a basement membrane. There were abundant pigment granules in the retinular pigment cells, and in the surroundings of the crystalline cone and rhabdom. The pigment granules in accessory pigment cells moved longitudinally under different monochromatic lights. They were distributed uniformly along the longitudinal axis in the ommatidium under white, green and yellow light, while mainly clustered in the distal of retinular cells and proximal of cornea under violet, blue and red light.

Conclusion There are no difference in external morphology and internal microstructure of compound eyes between male and female of B. dorsalis, and the compound eyes of both sexes are apposition eyes. Their compound eye adapts to environmental light changes by the mechanism of pigment granules moving longitudinally. This research can provide a theoretical basis for screening sensitive lights of B. dorsalis adult for light trapping.