First record of Steinernema diaprepesi (Steinernematidae) in Argentina.

LAX, P.; DEL VALLE, E.; RONDAN DUEÑAS, J.C.; CACCIA, M.G.; GARDENAL, C.N.; DOUCET, M.E

Coimbra

Congreso; XLIII Reunión Anual de la Organización de Nematólogos de los Trópicos Americanos (ONTA).; 2011

rganización de Nematólogos de los Trópicos Americanos (ONTA).

To date, the following entomopathogenic nematode species belonging to the Family Steinernematidae have been mentioned in Argentina: Steinernema carpocapsae, S. feltiae, S. glaseri, S. rarum, S. ritteri, and S. scapterisci. Samples were recently collected from sandy soil of a carrot field in the locality of Santa Rosa de Calchines (Department of Garay, Santa Fe province). The insect baiting method was then applied using larvae of Galleria mellonella. After 7 days, larvae showing signs of infection were placed individually in White traps to obtain infective juveniles; to confirm their pathogenicity, the latter were exposed to other larvae of the insect. An isolate of the genus Steinernema belonging to the “glaseri group” was detected. Morphological and morphometric studies were conducted following classical nematological techniques; they were complemented with the analysis of sequences of the rDNA ITS and D2-D3 regions. The sequences were compared with those known for other species of the mentioned group. Certain characters of the IJ (body length, distance from anterior end to excretory pore, tail length) and spicule length in males allowed the identification of the isolate as S. diaprepesi; these characters are diagnostic for the differentiation of this species from a close one, S. brazilense. In females, the presence of papillae-like structures in tail tip and vulva with low double-flapped epiptygma was observed. The analysis of the phylogenetic relationships (neighbor joining and maximum parsimony) among the isolate and several closely related species confirmed the results based on morphology and morphometry. This is the first report of S. diaprepesi in Argentina.