EFFETS DES PRATIQUES AGRICOLES SUR LA BIODIVERSITE DES ORTHOPTERES DANS L’OASIS DE GHARDAÏA

Abstract

After three years of monitoring (2016-2019), no less than 6256 individuals of Orthoptera were counted on 3 palm groves in Ghardaïa. These specimens are represented by 22 species belonging to 4 families. The presence of a herbaceous layer such as Cynodon dactylon and Setaria verticillata promotes the development of Gomphocerinae such as Ochrilidia gracilis. In contrast, the presence of a high proportion of date palms and fruit trees contributes to the decrease in the locust fauna. The density of locusts begins to increase in Spring (26 individuals/100 m2) to reach the maximum in Summer (58 individuals/100 m2). The highest densities are noted in the least maintained palm groves. In general, the values of the Shannon diversity index (H’) (1.84-2.63 bits) and the inverse of the Simpson index (4-12) gradually change in Spring and Summer where it is maximum, then decreases in Winter. alpha diversity is high in poorly maintained palm groves (2.62). This study indicated that the Orthoptera could be successfully used as bio indicators of oasis disturbance