Soós Árpád szerk.: Rovartani Közlemények (Folia Entomologica Hungarica 7/1-13. Budapest, 1954)
another from one generation to the next.Viruses and protozoa fulfil these requirements, bacteria and fungi being in this respect much more subject to several factors such as humidity of the air,sunshine,etc. Until now no natural diseases of Hyphantria cunea Drury could be observed in Hungary. In Czechoslovakia J. Weiser isolated a protozoan Microsporid,named Thelohania hyphantriae Weiser,from the caterpillar,which he thinks can be used for biological control. There are however some difficulties in multipliying such microsporidia parasiting in wild animals,to the desired extent.! tried therefore to infect the fall webworm with the Nosema bombycis ,a well-known pathogen of the silkworm, which can be reared easily in the growing caterpillars,in order to harvest large quantities. Besides a number of other species mentioned in a separate paper, I found Hyphantria cunea in a high degree susceptible to the disease.In 1953 100-100 fifth instar larvae kept in insectaries and on small bushes of Morus alba L.planted in dishes respectively were infected with spores of the Hosema bombyois . The caterpillars did not show any signs of the illnes but pupated 5 and 8 days respectl vely later than the control animals.In 1946,after hiberaisation 39 and 17 per cent resp.fewer adults emerged from these infected pupae and the adults lay 40 and 27 per cent fewer eggs than the controls, the parents being all infected with the spores of the Microsporid. The results of the hatching showed that about 40 per cent fewer larvae came out from the infected eggs. The young caterpillars showed a high mortality: 29 per cent died within 5 days, 41 per cent within 10 days and on the 20 th day only 9 per cent living specimens could be counted. Sven these died later so that only two of them reached the pupating stage, but in spite of this could not complete pupation. All the caterpillars showed heavy and typical signs of the disease. The control animals pupated at the rate of 76 per cent end no traces of the Microsporid could be detected among then*.,
