The cactus is a plant that has a great capacity to adapt to global warming and the increasing risks of drought. In Senegal, it belongs to the category of neglected and under-utilized species (NUS). Its introduction as a protective hedge around the perimeter of the Gueumbeul Special Fauna Reserve has led his proliferation in the reserve. This proliferation of the cactus considerably reduces the surface area preferred by animal species. In order to determine the causes of the cactus plants proliferation in the reserve, our objective is to study the role of red monkeys in the seeds dissemination. To this end, a questionary and an interview guide were respectively confectioned for the villagers and the reserve agents. The mapping of cactus and red monkey populations and their signs of presence was carried out. Cactus fruits and monkey droppings were collected in the reserve. The droppings as well as the seeds extracted from them were weighed. The results of interview and the percentage of cactus fruits in the monkey alimentation, revealed that monkeys are responsible for 78.6% of the spread of the cactus. The mapping also showed that cactus populations are more important in the western zone.

Keywords: Special Faunal Reserve of Gueumbeul, cactus, neglected species, dissemination, proliferation, red monkey