Mortality of Laemophloeus (Coleoptera, Cucujidae) infected with Mattesia dispora Naville (Protozoa, Schizogregarinaria)

Abstract

It was noticed that some stock cultures of Laemophloeus minutus Olivier and L. ferrugineus Stephen were showing an abnormally high mortality. The numbers of living larvae appeared to decrease, many pupae died inside their cocoons and most of the few adults which emerged died within a few weeks. As adult Laemophloeus live for about 6 months at the conditions under which the cultures were kept (25° C. and 70% r.h.) it was apparent that something was killing the beetles at all stages in development. Microscopic examination of dead larvae and adults which had been chopped up and mounted in Berlese's fluid (Swan's formula) revealed huge numbers of the lemon-shaped spores (sporocysts) or pseudonavicellae of a sporozoan parasite. Living larvae from infected cultures were dissected in saline, and smears were fixed in Bouin's fluid (aqueous) and stained with Heidenhain's haematoxylin. Other larvae were fixed in Bouin's fluid, sectioned, stained with Ehrlich's or Heidenhain's haematoxylin and eosin, cleared in xylol and mounted in Canada balsam. These preparations revealed various stages of a schizogregarine which appeared to be Mattesia dispora which was described by Naville (1930) from Ephestia kühniella Zell. (Lepidoptera, Phycitidae) and recorded by Musgrave & Mackinnon (1938) from Plodia interpunctella Hbn. (Lepidoptera, Phycitidae). Careful examination of sections and measurement of various stages confirmed this identification. All stages were found, with the possible exception of young gamonts formed by macronuclear schizogony.