Arnold, C., Hamacher, J., & Nahif, A.A. 2004 Occurrence of microsporidia, endosymbionts and viruses in the horse chestnut scale Pulvinaria regalis Canard (Homoptera : Coccidae).. Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz 111(2): 173-182.

Notes: The present study aimed to investigate the occurrence of microsporidia, endosymbionts and viruses in the Horse Chestnut Scale Pulvinaria regalis Canard (Homoptera: Coccidae), an introduced pest insect of more than 65 different plant species. Microsporidia could not be detected either in eggs or in three nymphal stages or in the adult scales. The number of endosymbiotic organisms increased continuously during the development of P. regalis. Mycetocytes appeared in the first nymphal stage for the first time. Their number and size increase considerably within the following developmental stages, merging into a mycetome in the adult scales. Two virus-like particles (VLP) were detected by electron microscopy (TEM). One VLP of 30 nm diameter was of isometric shape and had no outer or inner structures. The other VLP was 65 to 70 nm in diameter, had a hexagonal outline and a core of 4560 nm in diameter. The classification of the VLPs is discussed.