Abstract

SACKMANN, Paula. Effects of temporal variation and trapping methods on the efficiency of Coleoptera sampling in Loma del Medio Nature Reserve, El Bolsón, Río Negro. Rev. Soc. Entomol. Argent. [online]. 2006, vol.65, n.3-4, pp.35-50. ISSN 0373-5680.

The present study evaluates for a community of Coleoptera of sub-antartic forest the efficiency of a systematic sampling. In particular, the convenience of distributing sampling effort in time (at different moments within a season and between years) and the use of two different kinds of traps are evaluated. Ten sampling sites were selected in an Austrocedrus chilensis (Cupresaceae) and Nothofagus dombeyii (Fagaceae) forest within the Reserva Forestal Loma del Medio, El Bolsón, Río Negro. At each site, nine pitfall traps were placed covering a 100 m² surface, along with one Malaise trap. Four annual samplings (January, February, March and April) were carried out during three years (2002-2004). The abundance of species was higher in January-February than in March-April, while richness was similar and community composition differed markedly between periods for the three years. On the other hand, richness was similar when one, two or three years of sampling were considered and in general species composition was similar in different years for comparable periods. However, the accumulation of rare species became stable only after three years of sampling. Malaise traps were more efficient (number of species/individuals captured) than pitfall traps, but the sampling methods were highly complementary, capturing only 25% of species in common. In order to characterize the studied community it is recommended to that sampling efforts are distributed through a sampling season and that different trapping methods are used. Even though one year of sampling under the aforementioned conditions will be enough to have a general description of the Coleoptera community, at least three years will be necessary to reach a high level of sampling integrity. A list of species captured (N = 175), of which 14 are new records for Argentina, is included as an appendix.

Keywords : Coleoptera; Malaise traps; Patagonia; Pitfall traps; Sampling efficiency; Systematic sampling.

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