Abstract

LANGE, Carlos E.. Levels of experimental and natural sporulation of Nosema locustae (Microsporidia) in grasshopper and locust species (Orthoptera: Acridoidea) of Argentina. Rev. Soc. Entomol. Argent. [online]. 2003, vol.62, n.1-2, pp.15-22. ISSN 0373-5680.

Nosema locustae Canning, an intracellular sporogenic pathogen of the fat body of orthopterans used for the biological control of grasshoppers, became established in some grasshopper communities of Argentina after its introduction more than 20 years ago. Following standard methods for counting spores per individual insect affected, the levels of spore production by N. locustae was measured for three species of grasshoppers naturally infected [ Dichroplus elongatus Giglio-Tos, Dichroplus pratensis Bruner, Baeacris punctulatus (Thunberg)], and for six species experimentally infected [ Dichroplus maculipennis Blanchard, Dichroplus schulzi Bruner, D. elongatus, B. punctulatus, Ronderosia bergi Stal, Schistocerca cancellata (Serville)]. The levels of sporulation were relatively high in all species of the subfamily Melanoplinae (mean values varied from 2 x 10⁸ to 3,2 x 10⁹), while the production of spores was rare (9,5 % of the infected individuals) and low (maximum of 9,6 x 10⁶) in S. cancellata. There was no infection development in the Romaleidae grasshopper Elaeochlora viridicata (Serville). The values of sporulation reached by the melanoplines agree with the establishment of N. locustae in communities of grasshoppers in Argentina because a high availability of infective transmissible units (propagules) is a central factor for the transmission and persistence of a disease in a population of susceptible insects. Although the highest sporulation levels were reached in D. maculipennis, R. bergi appears to be, among the species used in this study, the best choice for in vivo production of N. locustae, because there is no obligatory embrionic diapause in its cycle, and its less reactive behaviour makes the handling of colony easier.

Keywords : Acridians; Melanoplinae; pathogen; transmission.

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