Nonoccluded, cytoplasmic virus particles and rickettsia-like organisms in testes and spermathecae of Diabrotica virgifera

Abstract

An ultrastructural study was conducted on the testes and spermateca of adult Diabrotica virgifera virgifera that exhibited a high incidence of abnormal sperm. The cytoplasm of spermatocyst cells was found to contain large masses of 24 to 26-nm virus particles assembled in loose aggregates or in tightly packed crystalline arrays. Double-tailed and frayed sperm in various stages of disintegration were associated with the spermatocyst cells. Similar virus particles in crystalline arrays were found in spermathecal epithelial cells and in muscle cells associated with the spermatheca. The size and appearance of the particles suggest that the virus is a picornavirus. Rickettsia-like organisms (RLO) were abundant in spermatocyst cells in addition to virus particles. These organisms were ca. 0.6 μm in diameter and up to 2.7 μm in length and were found either singly or in various-sized aggregates. The RLOs were each surrounded by a double unit membrane and colonies composed of several individuals were enclosed within a cellular vacuolar membrane. Although the virus appears to be involved in the production of abnormal sperm, the RLOs appear to act as harmless symbionts as they were abundant in spermatocyst cells that were free of damaged sperm and were present in other tissues.