Ensamblaje de escarabajos Melolonthidae (Coleoptera: Scarabaeoidea) asociados con pasturas en el departamento del Caquetá y su posible relación con la salubridad edáfica

The Caqueta hillsidezone is a part of the Colombian Amazon region (mean pluvial precipitation 3600 mm; 260 m.a.s.l., 26oC). It shows a mega diverse environment, ecologically fragile as the soils have been increasingly degraded. This research had the purpose of monitoring biological aspects of degraded soils resulting from extensive livestock production systems.A comparative sampling of richness and abundance variation of edaphic scarabs on cattle ranches of five municipalities (San Vicente del Caguan, El Doncello, Belen de los Andaquies, Albania y Valparaiso) was used. Adults were sampled using light traps and larvae by excavation of soil quadrants on pasture and forest relict plots during dry and rainy seasons. 26 Melolonthidae species were recorded, a moderate diversity assemblage including 16 and 2 new records for the Caqueta Department and Colombia, respectively. 475 larvae and 11 morphospecies were collected, their distribution and abundance varied significantly according to management, seasons and localities, highlighting the low beta diversity of the region (11 species) and the low alpha diversity by municipalities (five species), including /ust <<= saprophagous (Cyclocephala, Euetheola), while the other ones (Phyllophaga, Plectris, Barybas, Bolax) are rhizophagous. This balance showed the soil degradation presumable due to the soil organic matter decreasing and deterioration of soil physical properties as a consequence of extensive livestock production systems. It is recommended to extend these studies to a large geographical scale in order to detail the diagnose and to redefine soil management strategy such to focus on sylvopastoral systems with improved grasses, herbaceous and shrubby legumes and arboreal strata.