Characteristic light and electron microscopic features of adelina melolonthae, a coccidian pathogen of the european cockchafer, melolontha melolontha (coleoptera/scarabaeidae)

Purpose The aim of this study was to investigate and document the characteristic electron microscopic features of the oocyst of Adelina melolonthae, a coccidian pathogen of the European cockchafer, Melolontha melolontha (Coleoptera: Scarabaeidae). Methods Larvae of M. melolontha were collected at Ordu, Turkey. Each larva was dissected in insect Ringer solution. Adeleid oocysts from the tissue that is suspected to Contain coccidian infections were examined under a light microscope (Zeiss), a scanning electron microscope (FEI Quanta 200) and transmission electron Microscope (Philips EM 208). Results Spherical to ellipsoidal oocysts measure ca. 24-44.5 mu m (mean 35.6 mu m) in diameter (n = 50) and include up to twelve sporocysts. The oocyst wall has double layers; the outer layer measured 400-500 nm in thickness and the inner one 10-25 nm. Sporocysts including two sporozoites are rounded ca. 11-12.5 mu m (mean 11.7 mu m) in diameter. The sporocyst wall consisted of only one 70-80-nm-thick layer. The sporozoites are ellipsoidal and measured 9-11 mu m length and 3-4 mu m in width. Sporocysts include residual bodies. Conclusion In the present paper, the morphology and ultrastructure of the oocyst of A. melolonthae is documented for the first time and compared with other Adelina and coccidian species infecting insects. The results in this study confirm his identification and justify the classification as a separate species A. melolonthae, which differs from other Adelina species.