THE FATE OF NOSEMA-LOCUSTAE (MICROSPORIDA, NOSEMATIDAE) IN ARGENTINE GRASSHOPPERS (ORTHOPTERA, ACRIDIDAE)

Surveys to detect Nosema locustae, a microsporidian pathogen of orthop terans introduced in Argentina several times from 1978 to 1982 to cont rol pest grasshoppers, were conducted during the 1994 and 1995 seasons at locations in Buenos Aires and La Pampa provinces. A total of 7535 grasshoppers collected from 13 different sites were examined, Infected grasshoppers were found at 4 of the sites, 2 of them 75 km from the c losest introduction site. Infections were diagnosed in 10 species: 7 M elanoplinae (Baeacris punctulatus, Dichroplus elongatus, D. pratensis, D. vittatus, Neopedies brunneri, Scotussa daguerrei, and S. lemniscat a), 2 Gomphocerinae (Staurorhectus longicornis and Rhammatocerus pictu s), and 1 Romaleidae (Diponthus argentinus). Prevalence of infection r anged from 0.7% in D. pratensis to 33.3% in R. pictus and averaged 7.9 %. B. punctulatus appeared as the most susceptible species to infectio n. N. locustae is well established in grasshopper communities of centr al Argentina. Some comments are included about concerns that were rais ed on the use of exotic agents for the control of native pests. (C) 19 95 Academic Press, Inc.