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During field tests with Bacillus popilliae Dutky (“Melolontha” strain) for the control of larvae of the common cockchafer, Melolontha melolontha (Linnaeus), we observed an epizootic caused by the microsporidian Nosema melolonthae (Krieg) in a meadow, 12 1 2 acres in size, at Sille-le-Guillaume, in Sarthe, France. The appearance and development of this epizootic have been observed since 1959 and some ecological characters of the disease will be described. These are: relationship to ecdysis, specificity, and resistance.

(1913). The Pathogenicity of Nosema Apis to Insects other than Hive Bees. Annals of Tropical Medicine & Parasitology: Vol. 7, No. 4, pp. 569-579.

A microsporidian parasite of the jack-pine budworm is described and found to be very similar to Perezia fumiferanae Thom., which attacks the spruce budworm. The differences between the two species of Microsporidia are not considered great enough to justify the creation of a new species at the present time; however, with the continued isolation of the host species, the differences may become greater.

Examinations of living and dead larvalPyrausta nubilalis (Hubner) collected in the field over a four-year period indicate that infections caused byPerezia pyraustae Paillot are widely distributed within populations ofP. nubilalis in Illinois. Observed fluctuations in the incidence of the parasite among living and dead insects collected in various seasons was taken as evidence that the disease interacts with temperature to cause mortality in populations of the host.

A new microsporidian, Nosema leptinotarsae sp. n., is described from adults of Leptinotarsa decemlineata (Say) collected in Nesterov and Obrushino of the Lvov region, Soviet Union. The parasite infects blood cells which show great hypertrophy. Twenty percent of adults from the host populations were infected by the protozoan. This indicates that the pathogen seems to play an important role as a mortality factor of the Colorado potato beetle.

(1912). The Morphology and Life History of Nosema Apis and the Significance of its Various Stages in the so-called ‘Isle of Wight’ Disease in Bees (Microsporidiosis). Annals of Tropical Medicine & Parasitology: Vol. 6, No. 2, pp. 163-195.

Thelohania californica was transmitted transovarially to hybrids of Culex tarsalis × C. erythrothorax and C. tarsalis × C. peus. The parasite did not develop in the former hybrids and developed abnormally in the latter. It was concluded that the parasite is probably host specific and that C. tarsalis is more closely related to C. peus than C. erythrothorax.

International audience

SYNOPSIS A microsporidan found parasitic in Anopheles gambiae in Tanzania was identified as Nosema algerae Vavra & Undeen, 1970. Its development was traced in laboratory-bred Anopheles stephensi. Spores were oval, 3.0-4.3 μ× 1.8-2.5 μ and had filaments 40-60 μ long; schizonts were uni-, bi- or tetranucleate; elongate sporonts gave rise to 2 sporoblasts. The parasite attacked almost every tissue of the body of the larvae, pupae and adults including the ova, but transovarial transmission was thought to be unimportant as infected ova did not develop into viable larvae. Hosts reacted to the presence of the parasite by encapsulating some spores in a coat of melanin. The parasite was lightly infective to several species of culicine mosquitoes, but the infection was limited mainly to the nervous system, mid-gut epithelium and Malpighian tubules. The species of Nosema parasitizing mosquitoes are reviewed.

A microsporidian parasite, Nosema cerasivoranae n. sp., is described from the ugly-nest caterpillar, Archips cerasivorana (Fitch). This parasite primarily attacks the malpighian tubules and silk glands although other tissues are also infected.

In connection with a survey of wild Anopholes gambiae for natural infections of malaria, conducted at the Liberian Institute, Harbel, Liberia, West Africa, one of us made some thousands of midgut dissections during the period from June 1955 until April 1956 (Fox, 1957). From time to time a wild mosquito was found to be infected with a microsporidian parasite. The rate of this natural infection was not recorded but was exceedingly low. Colonies of A. gambiae had been maintained at the Institute continuously for the previous 4 years without difficulty. During the summer of 1956 an outbreak of nosematosis occurred, quickly reaching nearly epizootic proportions and spreading to the colony of A. melas. Because infected mosquitoes are not suitable for use in malaria study, the colonies had to be destroyed. A few infected strains were kept for further study of the parasite. The purpose of the present paper is to record the pathology of the microsporidian infection, identified as Nosema stegomyiae, in adult A. gambiae and to present certain observations on nosematosis in mosquitoes. Nosema stegomyiae (Marchoux, Salimbeni and Simond), 1903, has reniform or comma-form spores 4-7 microns long and 2-3 microns wide. It invades the gut, muscles, air sacs, coelomic lining, neural ganglia and ovaries of adult mosquitoes, and was originally observed as a parasite of Aedes. N. stegomyiae Lutz and Splendore, 1908, described as a new species, and N. anophelis Kudo, 1924, are synonyms. Two other microsporidia parasitize mosquitoes: Thelohania grassi Nicholson, 1921, had earlier been recorded but not described by Grassi (1901), Ross (1906), Stephens and Christophers (1908); Plistophora culicis Weiser, 1947, with spores 5 microns long and plasmodia 15 microns in diameter, has been found and fully detailed by Garnham (1956) and Canning (1957). Both these species sometimes invade the larvae. One of us (JW) is preparing a monographic revision of the microsporidia.