Estudio de los agregados de dípteros sarcosaprófagos y su relación con los ecosistemas naturales de la Comunidad de Madrid

Resumen

The order Diptera constitutes a particularly diverse group of insects with great economic and sanitary importance, both aspects accentuated in the case of those species which breed in decomposing organic matter. However, despite their interest and applications, the knowledge about the ecology of the sarcosaprophagous Diptera is still very limited in the Iberian Peninsula. The present work shows a study about the assemblages of sarcosaprophagous Diptera in the seven typical natural ecosystems of the Community of Madrid, a representative region of the peninsular centre. A total of 22202 specimens belonging to 11 families and to 87 species of sarcosaprophagous Diptera were collected with carrion-baited traps in 21 localities between June 2006 and May 2007. The most abundant families were Calliphoridae (41% of the total captures), Muscidae (36%), Heleomyzidae (9%), Sarcophagidae (7%), Piophilidae (5%) and Ulidiidae (2%). The remaining families constituted less than 1% of the total captures. Moreover, three new Piophilidae species for the Iberian fauna were recorded: Piophila megastigmata, Prochyliza nigricornis and Thyreophora cynophila. The sex-ratio was female-biased in families Calliphoridae, Muscidae and Sarcophagidae, but no significant differences were observed in families Heleomyzidae, Piophilidae and Ulidiidae. The use of nonparametric methods and the extrapolation from species accumulation curves confirmed the representation of the sampling and calculated an estimation of the species richness for each locality; while diversity values were obtained by Shannon and Simpson indexes and contrasted with dominance and equitability indexes. The influence of the characteristics of habitat in the species diversity was also studied; with significant differences considering altitude, slope, sun radiation and mean temperature. Furthermore, the main part of the individuals was collected in the warmest months showing a seasonal progression in the appearance of different species, as well as a reduction in the optimal period of Diptera activity at oromediterranean ecosystems, where the number of registered species and their seasonal breadth were always lower. In this sense, it is possible to differentiate three groups of ecosystems depending on their typical species assemblage composition; which coincides with the three sampled bioclimatical levels, with the greatest differences comparing the assemblages from oromediterranean ecosystems with those from mesomediterranean and supramediterranean ecosystems. Differences between the assemblages from different ecosystems were clear in summer and autumn, while such differences were less significant in winter and spring.