1. L2EP, Faculty of Sciences and Technologies , University of Lille , Villeneuve dAscq , France .
2. Department of Mathematics, Faculty of Science and Technology , Cadi Ayyad University , B.P. 549, Av. Abdelkarim Elkhattabi, Guèliz, Marrakesh, 40000 , Morocco .
3. Laboratory of mathematics and population dynamics , Faculty of sciences Semlalia Marrakesh , Morocco .