Naturalized biocontrol agent may help in the management of pest grasshoppers and locusts in Argentina.

C.E. LANGE

Phoenix

Encuentro; Lauching of Global Locust Initiative; 2018

Arizona State University

Worldwide two entomopathogens have been developed, registered, and are commercialized as agents for grasshopper and locust biocontrol, the fungus Metarhizium acridum and the microsporidium Paranosema locustae. Metarhizium acridum has never been used in Argentina but native strains of other fungi in the Ascomycota Hypocreales have been isolated and are under evaluation. On the contrary, following introductions from North America in Argentina, P. locustae became established in three areas of the country: two in north-western Patagonia and the other in the Pampas. In two of these areas, the pathogen is so common affecting several species of grasshoppers after so many years of the introductions that it should be considered as a naturalized species. After years of field monitoring and laboratory experimentation, the presentation will update the status of P. locustae in grasshopper communities of Argentina in terms of its host range, prevalence, and geographic distribution. Given the effects produced by P. locustae on its hosts, including increased mortality, reduced fecundity and longevity, altered development, and decreased activity and vigor, among others, its levels of presence must be affecting abundance of susceptible grasshopper species, particularly so since P. locustae represents a relatively new disease spreading through a number of novel, naive hosts. The absence of historical quantitative data on grasshopper density in establishment areas does not allow for a clear cause-effect impact on grasshopper abundance due to the naturalization of P. locustae. However, anecdotal information by ranchers, farmers, and extensionists suggest that both intensity and frequency of grasshopper outbreaks diminished after its introduction.