Fine Structure of the Visual System of Arge similis (Hymenoptera, Argidae)

SIMPLE SUMMARY: Arge similis is a notorious pest on rhododendron plants. The fine structure of the compound eyes of A. similis adults were examined by light, scanning, and transmission electron microscopy. Each ommatidium consists of a lamellated cornea, a crystalline cone with eucone type, and a centrally fused rhabdom composed of eight retinular cells. ABSTRACT: External morphology and ultrastructure of the visual system of Arge similis (Vollenhoven, 1860) adults were investigated by light microscopy, scanning electron microscopy, and transmission electron microscopy. Each compound eye contains 2022 ± 89 (mean ± SE) facets in males and 2223 ± 52 facets in females. Arge similis has an apposition kind of compound eye composed of a cornea, a crystalline cone of four cone cells, and a centrally fused rhabdom made up of the rhabdomeres of eight large retinular cells. Each crystalline cone is surrounded by primary and secondary pigment cells with black spherical screening pigment granules measuring 0.60 ± 0.02 and 0.41 ± 0.01 μm in diameter, respectively. Based on our findings, the compound eye of A. similis can be expected to exhibit high adaptability to light intensity changes.