Soil/litter beetle abundance and diversity along a land use gradient in tropical africa (oumé, ivory coast)

Beetles represent acomponent of arthropods that contributes to enrichment and circulation of mineral elements retained in litter and the topsoil. We have studied beetle abundance, diversity, and distribution in response to anthropogenic activities (farming, urbanization, etc.). Two collecting methods were used: soil monoliths extraction, and sifting and processing of soil and litter samples in a mini-winkler extractor. This study was conducted in the central-western part of Ivory Coast, near Oume in eight agroecosystems with five types of habitats. Our results showed that secondary forests had the highest beetle abundance, but the highest diversity was found in the fallows. The families represented in the majority of agroecosystems are Staphylinidae, Scydmaenidae, Curculionidae, Pselaphidae, Scarabaeidae and Carabidae. The regenerating forest plantations and cocoa plantations were characterized by lower beetle abundance and diversity. The study demonstrated that beetle abundance and diversity were affected by human activities and depended on the intensity of land use. Les Coleopteres sont une composante des arthropodes qui participent a l’enrichissement et a la circulation des elements mineraux de la litiere et du sol. L’abondance et la diversite des Coleopteres ont donc fait l’objet d’une etude pour voir l’impact des activites anthropogeniques (agriculture, urbanisation, etc.). Deux methodes de collecte ont ete utilisees : extraction a partir des monolithes du sol, et extraction des Coleopteres a partir des winklers apres tamisage des echantillons de sol et de litiere. Les travaux se sont deroules dans le centre ouest de la Cote d’Ivoire, pres de Oume dans 8 agroecosystemes formant cinq types d’habitat. Il ressort des resultats que les forets secondaires ont l’abondance la plus elevee mais, la diversite la plus elevee est trouvee en jacheres. Les familles presentes dans la majorite des agroecosystemes sont les Staphylinidae, Scydmaenidae, Curculionidae, Pselaphidae, Scarabaeidae et les Carabidae. Les agroecosystemes reboises et les cacaoyeres sont caracterises par les plus faibles abondances et diversites. Ces travaux ont montre que l’abondance et la diversite des Coleopteres du sol sont affectees par les activites humaines et cela dependent de l’intensite d’utilisation du sol. Keywords: Beetle, abundance, diversity, agroecosystems, anthropogenic activities