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In this study a and b diversity patterns of five leaf litter arthropod groups (ants, predatory ants, oribatid mites, spiders and other arachnids) were described and compared in 39 sampling patches of a transformed landscape in southwestern Colombia, that represented five vegetation types: secondary forest, riparian forest, giant bamboo forest, pasture and sugarcane crop. It was also assessed whether some taxa could be used as diversity surrogates. A total of 6,765 individuals grouped in 290 morphospecies were collected. Species richness in all groups was lower in highly transformed vegetation types (pasture, sugarcane crop) than in native ones (forests). In contrast, there were no clear tendencies of b diversity among vegetation types. Considering sampling patches, 0.1-42% of the variation in a diversity of one taxonomic group could be explained from the a diversity of another, and 0.2-33% of the variation of b diversity of a given taxon was explained by that in other groups. Contrary to recent findings, we concluded that patterns of a diversity are more congruent than patterns of b diversity. This fact could be attributed to a sampling effect that promotes congruence in a diversity and to a lack of a clear regional ecological gradient that could promote congruent patterns of b diversity. We did Electronic supplementary material The online version of this article (not find evidence for an ideal diversity surrogate although diversity patterns of predatory ants had the greatest congruencies. These results support earlier multi-taxon evaluations in that conservation planning should not be based on only one leaf litter arthropod group.

In the mid-watershed of the Nima River in the Colombian Central Cordillera, the richness of staphylinids was estimated in association with 35 landscape elements classified as mature forest, secondary forest, riparian corridors, pastures and cypress plantations. For each element, two linear transects were traced, each one with six sample units, consisting of a pitfall trap and a 1 m 2 sample of leaf litter, processed in mini-Winkler sacks. There were 2623 specimens grouped into 139 recognizable taxonomic units; 13 subfamilies were recorded: Pselaphinae, Aleocharinae, Paederinae, Staphylininae, Tachyporinae, Osoriinae, Oxytelinae, Piestinae, Scaphidiinae, Euaesthetinae, Megalopsidiinae, Steninae and Omaliinae. The subfamilies with the greatest richness were Pselaphinae (40 species), Aleocharinae (39) and Paederinae (22). The highest number of species was found in the secondary forests (105 species), followed by the riparian corridors (98); whereas the mature forest was the element with the fewest species (30). The diversity of species components (a, b and c) was analyzed using the additive partition model based on four spatial scales: sampling units, transects, elements and types of vegetative cover. The elements and types of ground cover scales were the main contributors to total richness percentages. The subfamilies Aleocharinae, Paederinae, Pselaphinae and Staphylininae had component diversity patterns that were equal to the overall assemblage. A significant correlation of the richness of each subfamily with that of the assemblage was found.

Understanding the variation of diversity patterns requires analysis at multiple spatial scales. In this study we estimated the diversity components (alpha, beta and gamma) of the spider community at El Vínculo Natural Regional Park, using the additive partitioning of diversity (species richness, Shannon's diversity index and Simpson's index) for the first time on this taxon in Colombia. We collected the specimens following a nested sampling design that consisted of two spatial scales. At the local scale, we quantified additive diversity components in 238 sampling units, and at the regional scale in five vegetation types. Total observed regional diversity (γ) was partitioned into its additive components: within sampling units (α1), among sampling units (βl) and among vegetation types (β2). We used the same approach to compare common and infrequent spider species and to compare sampling methods. A total of 1565 adult spiders and 72 identifiable juveniles, including 193 morphospecies from 36 familie..

Actualmente se está incrementando la utiliza­ción de las áreas de sabana con el estableci­miento de forrajes introducidos, como pastos del género Brachiaria. A pesar de la buena adaptación de los Brachiaria a suelos ácidos e infértiles, presentan una alta susceptibilidad al salivazo de los pastos Aeneolamia spp.. Aquí se reportan los resultados de un estudio sobre las hormigas asociadas a las pasturas nativas e introducidas y su papel como depredadores del salivazo. Se encontró un grupo de especies de hormigas depredadoras generalistas, las cuales consumen los huevos del salivazo dis­puestos artificialmente en el campo. Solenopsis spp., Wasmannia sp. y Pheidole spp. fueron las hormigas que se observaron de manera más persistente sobre las masas de huevos y ninfas de primer instar del salivazo. Otras es­pecies como Paratrechina sp., Ectatomma ruidum Roger y Camponotus sp.1 también se observaron consumiendo principalmente hue­vos de la plaga. Para estudiar la diversidad, composición específica y abundancia de las hormigas asociadas a las pasturas nativas e introducidas muestrearon parcelas con ce­bos colocados a diferentes distancias. Con los cebos colocados a 5 m se capturó hasta el 83% de las especies colectadas utilizando varios métodos de colección más dispendiosos, como captura manual y excavación de nidos. Con todos los métodos se colectó un total de 41 especies de hormigas asociadas a todas las pasturas. Entre las pasturas introducidas, B. decumbens cv. Basilisk tuvo el mayor número de hormigas asociadas (18 especies). Tambien se documentaron los patrones de distribucion espacial de los nidos de Brachymyrmex sp., E. ruidum y, Camponotus sp. 1, antes y despues de la preparacion del suelo para la siembra de un lote de hibridos de Brachiaria. Los nidos de Camponotus sp. 1 no aparecieron despues de la preparacion del suelo, pero se encontraron nidos de una especie de Solenopsis.