Here, we describe a new microsporidium Percutemincola moriokae gen. nov., sp. nov., which was discovered in the intestinal and hypodermal cells of a wild strain of the nematode Oscheius tipulae that inhabits in the soil of Morioka, Iwate Prefecture, Japan. The spores of Pe. moriokae had an average size of 1.0 × 3.8 µm and 1.3 × 3.2 µm in the intestine and hypodermis, respectively, and electron microscopy revealed that they exhibited distinguishing features with morphological diversity in the hypodermis. Isolated spores were able to infect a reference strain of O. tipulae (CEW1) through horizontal transmission but not the nematode Caenorhabditis elegans. Upon infection, the spores were first observed in the hypodermis and then in the intestine the following day, suggesting a unique infectious route among nematode-infective microsporidia. Molecular phylogenetic analysis grouped this new species with the recently identified nematode-infective parasites Enteropsectra and Pancytospora forming a monophyletic sister clade to Orthosomella in clade IV, which also includes human pathogens such as Enterocytozoon and Vittaforma. We believe that this newly discovered species and its host could have application as a new model in microsporidia–nematode association studies.

Collections of the leaf beetle Henosepilachna elaterii Rossi, 1794 (Protozoa: Microspora) were carried out monthly from July 1988 to June 1991, from melon and cucumber plants in Senegal. Of the 1895 larvae and adults collected and examined, 1223 (64.53%) were infected with Nosema henosepilachnae Toguebaye and Marchand, 1984. The monthly infection prevalence ranged from 51.28% to 87.30%. These observations indicate that the infection due to N. henosepilachnae is prevalent in the natural populations of H. elaterii.

Silkworm larvae infected transovarially with Nosema bombycis were fed with an aqueous suspension of Bavistin (50% carbendazim w/w) at 2 and 3% concentrations. The treatments increased the survival of worms and reduced the pebrine infection in the lot significantly, although complete elimination of infection was not observed. Significant beneficial effects of the treatments at 2 and 3% were also observed with respect to larval, cocoon and cocoon shell weights and cocoon to shell ratio. However, treatments with Bavistin at 4% concentration produced an adverse effect on cocoon characters.

An experimental microspodiosis has been stimulated within Heliothis armigera (Lepidoptera, Noctuidae). The microsporidian used was Nosema manierae, a natural parasite of Chilo zacconius (Lepidoptera, Pyralidae). Nosema manierae causes high mortality in the larvae and the nymphs.