ECOLOGICAL IMPACT OF TROPHIC DIET OF MANTIDS IN GHARDAIA (ALGERIAN SAHARA)

In order to identify the diversity and the characterization of a group of predatory insects which is Mantodea, a special study of this group took place in a dryland habitat which is Ghardaïa (Algerian septentrional Sahara). Catches come from several sampling sites corresponding to several habitats (Reg, Wadi and palm grove). Twelve species belonging to five families are inventoried of which 2 species are endemic; Eremiaphila mzabi and Eremiaphila moreti not yet reported in Algeria.The palm grove accommodate the largest species richness (S = 9 species). Mantidae is the richest family (S = 4). The palm grove has a diversity index H' going from 1.42 bit to 1.66 bit and equitability E varies between 0.73 and 0.75. A gradient of vegetation cover reveals stratification in three habitats: palm grove, river and Reg. This heterogeneity of landscapes seems to influence Mantids diversity which is proportional to the vegetation cover, except for the genre Eremiaphila. Mantids identified in these habitats can be classified in three groups, a first group strictly related to palm grove, a second subservient to the natural habitat Reg and a third group with no net belonging, being simultaneously present in both habitats. An inter-habitat variability is emphasized and strata preferences can be distinguished for each species of. The feeding activity of Mantodea is estimated by analyzing their faeces. The diet of mantis confirms their strong entomophagy. For Sphodromantis viridis, the diet is composed of 42.7% of Hymenoptera followed by 19.7% of Aranea (H = 1.68 bit, L = 0.22; E = 0.38). For Amblythespis granulata, analysis of the content of feces reveals 37.7% of Orthoptera (H = 1.58 bits, Simpson’ index = 0.20 and equitability = 0.42). This potentially gives them an impact on populations of prey species.