Virus-like particles in testes of Heliothis virescens, H. subflexa, and backcross males derived from the hybridization of H. virescens males × H. subflexa females

Virus-like particles, bacteria and microsporidia affect spindle-associated membranes in spermatocytes of Lepidoptera species

Larval testes of four Lepidoptera species were examined using electron microscopy. The testes of one species, the Mediterranean mealmoth Ephestia kuehniella (Pyralidae), were devoid of intracellular pathogens and serve as a control. In this species, metaphase spindles of primary spermatocytes showed a thick layer of perispindle membranes. The membranes were structurally very similar to the agranular endoplasmic reticulum. Membranes of this type occurred also at high frequency throughout the spindle matrix. The analysis of larval testes of Pieris brassicae (Pieridae) revealed virus-like particles within spermatocytes. In another species, Philudoria potatoria (Lasiocampidae), the spermatocytes possessed intracellular bacteria. Whereas the pathogens were found within the germ cells in these species, a fourth species, Plutella xylostella (Plutellide), showed microsporidia within somatic cells of the testis sheath. In all the infected animals, the mass of perispindle membranes was reduced in comparison with spermatocytes of E. kuehniella. However, spindle structure appeared regular in the infected animals. This indicates that a thick layer of perispindle membranes is not decisive for spindle assembly and function in male meiosis of Lepidopera.