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Observations on Perezia pyraustae Paillot, a Microsporidian Parasite of the European Corn Borer

1952; American Society of Parasitologists; Volume: 38; Issue: 1 Linguagem: Inglês

10.2307/3274171

1937-2345

I. M. Hall,

Insect Resistance and Genetics

A considerable number of diseased specimens of the European corn borer, Pyrausta nubilalis (Hiibner), were received during 1950 by the Laboratory of Insect Pathology (Division of Biological Control, University of California) from K. D. Arbuthnot of the U. S. Department of Agriculture, European Corn Borer Research Laboratory, Ankeny Field Station, Des Moines, Iowa, where general research on the European corn borer is being conducted under the supervision of W. G. Bradley. Examination and study of these specimens by E. A. Steinhaus (1951a) of our laboratory revealed the presence of several different pathogens (fungi, bacteria, and protozoa), among them a species of MICROSPORIDIA. The data relative to the fungi and bacteria are the subject of another report (Steinhaus, 1951b). Since MICROSPORIDIA are obligate parasites, and since the European corn borer is not present in California, it was necessary, in order to maintain the protozoan, to find a suitable host among the local insects readily available and adaptable to insectary rearing. The buckeye caterpillar, Junonia coenia Hiibner, proved to be such a host. Preliminary cross-infection tests were accomplished by feeding the caterpillars plantain dipped in a spore suspension of the microsporidian from one corn borer larva. This specimen, collected in Black Hawk County, Iowa was one of 46 received by the laboratory on August 5, 1950. After 12 days, two of the four test Junonia larvae were found to contain microsporidian spores and vegetative stages, while the three control larvae were not infected. A second cross-infection test was made using a greater number of Junonia larvae. The spore material used to contaminate the insect food was prepared from four European corn borer specimens from a shipment of 32 received on August 8, 1950. Two of the specimens were collected in Henry County, Iowa, one in Boone County, Iowa, and one in Bremer County, Iowa. Three specimens contained only microsporidia while one contained both microsporidia and a Beauveria fungus. Slides were made on the sixth, eighth, eleventh, and thirteenth days after the Junonia larvae were fed the contaminated food. The slides were fixed with methyl alcohol and stained with Giemsa. Vegetative stages were evident on the eighth day, mixed vegetative stages and spores on the eleventh day, and mostly spores were present on the thirteenth day. Observations on the life history of the microsporidian revealed that each sporont forms two spores. Since the infected cells of the Junonia larvae are not hypertrophied, this microsporidian, according to the present systematic concepts, may be placed in the genus Perezia Leger and Duboscq, 1909. This brings forth a dubious aspect of classification of the MICROSPORIDIA in which two genera (i.e., Glugea Thelohan and Perezia Leger and Duboscq are distinguished not on the basis of their own characteristics but upon pathological changes occurring within the host