Microsporidia as grasshopper control agents in Argentina.

C.E. LANGE

Kunming

Congreso; 11th International Congress of Orthopterology; 2013

Orthopterists Society y Yunnan University

Research cooperative projects between scientists of La Plata National University (UNLP) and the United States Department of Agriculture (USDA) in the late 1970´s and early 1980´s prompted the study of microsporidia as possible biocontrol agents of grasshoppers in Argentina, a previously unexplored field of research in the country. Microsporidia are spore-forming, unicellular eukaryotic obligate parasites of which insects as a whole are one of the main host groups. As in other parts of the world, absolute reliance on chemical insecticides against some of the 10-15 pest grasshopper species of the country provided the justification underlying the search for more environmental-friendly alternatives of control. Prior to the implementation of the projects no reports on grasshopper microsporidia were available in Argentina. Since then, three native microsporidia have been fully described (Liebermannia dichroplusae, Liebermannia patagonica, Liebermannia covasacrae), several other Liebermannia-like isolates have been detected and are under study, and the fate of the introduced microsporidium Paranosema locustae was monitored for years in the Pampas, and to a lesser extent in two other introduction areas in Patagonia. The presentation will review the state of knowledge on the microsporidia associated with grasshoppers in Argentina. None of the native species so far discovered appear to be useful for control purposes due to constraints in transmission, host range, and pathogenecity. On the contrary, P. locustae, well established in the western Pampas and in Loncopué, Neuquén province (north-western Patagonia), seems to be of value as a long-term control factor. Simultaneously, some non-target grasshopper species may be negatively affected, particularly those belonging to subfamilies of recognized susceptibility and having small populations and restricted geographic distribution. However, in spite of the apparent usefulness of P. locustae against grasshoppers in Argentina, aside from some incipient interest by organic farmers and a few provinces, what has been called ?the chemical paradigm? still prevails.