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Microsporidia Amblyospora opacita Kudo, 1922 was tested in laboratory conditions as an agent of biological control of vectors of pathogens of many dangerous infectious and invasive diseases - blood-sucking mosquitoes (Aedes caspius Pallas, 1771). The effect of microsporidiosis on mortality, growth, developmental period, molting and sex of larvae was studied. It was found that the prepared suspension titer of 1.1×105 spores / ml is more effective (up to 90.7%) against the larvae of bloodsucking mosquitoes. [ABSTRACT FROM AUTHOR]

It is established, that infestation with Gurleya sp. (Microsporidia, Gurleyidae) changes the behaviour of its host Moina macrocopa (Straus, 1820), a crustacean inhabiting pools. Heavily infested host individuals attach to surface film of water before their death by senescence. As a consequence, their dead bodies filled with spores of the parasite adhere to objects dipped in water that probably facilitates the transfer of spores by birds and cattle to other pools. Weakly infested or uninfested individuals drown after the end of their ontogenesis. Distribution of the microsporidian spores by two different ways (with attached dead bodies of the hosts or with bottom sediments) makes invasion of a new host more probable.

An experimental microsporidiosis of the wax moth caterpillars from laboratory population had been caused by oral infecting of early stages larvae and by intracavity injections of the spores of the microsporidian species Vairimorpha ephestiae. Peculiarities of microsporidiosis proceeding, manifestations of host defence reactions, and also an effect of the temperature of caterpillars cultivation and conditions of spores keeping on liability of the insects to the infection were studied. The effect of the microsporidia on the host organism was the early death or the delay of larvae development, but in several cases external manifestations of the effect of the parasite on the host were absent. The development of the parasites from the moment of infecting to the appearing of the mature spores congestions in the host organism proceeded 6 days. Microsporidia invaded insect fat body and caused its hypertrophy and disappearance of lipid granules. In the intestine and salivary glands microsporidia were not observed in the period from 6 to 16 day of the development. On the final stage of microsporidiosis the all contents of fatty tissue cells were replaced by spores of microsporidia. Under microscope only diplocaryotic spores of the Nozema type had been found in infected and died specimens, but not octospores. The spores threw out polar tubes under the change of pH in incubating solution from neutral to alkaline. The effects of microsporidiosis on the wax moth haemolymph were the increased rate of prohaemocytes, appearing of multinuclear free-circulating cells at 6 day after infection, and suppression of the reaction of haemolymph melanization with the mass sporogenesis of the parasite. The characteristic symptom of the wax moth microsporidiosis had been revealed, accumulation of black points and small spots of irregular form under cuticle ("reaction of attretization"). Increase of the temperature of insect cultivation up to 32 degrees C during 3 days after infection contributed to the full deliverance of the insects from the infection in first and second generations. It can be considered as a method of treatment of wax moth laboratory colonies from microsporidiosis. Oral infection of III and IV stage caterpillars by the spores being kept during 3-6 months under 4 degrees C in form of water suspension caused the death of 63.0-61.5 and 91% of caterpillars being cultivated under 25 and 21 degrees C respectively. Under the temperature of cultivation equal 30 degrees C the mortality did not differ from the control sample (8-10%). The spores extracted from dried bodies of caterpillars lost their vitality. It was demonstrated by the test on infectious ability in vivo and by acridine orange staining. This host-parasite system appears to be perspective in investigations of resistance mechanisms in insects and immunosuppressive features of entomopathogen microsporidia.