EFFECT OF PASTORAL ACTIVITIES UPON LOCUST POPULATIONS IN THE SIROUA MASSIF (MOROCCO)

A gregarisation site of Dociostaurus maroccanus (Thunb.) was studied d uring five annual surveys (1988-1993), The study site is on a high alt itude pasture (2 300 m) in The Anti-Atlas mountains where flocks graze during the summer season, On the 2 850 ha Poa bulbosa's pasture the n umber of sheeps and goats was estimated at 7 200 heads (one head per 0 .4 ha). Acrididae (18 species) and their predators (14 insects and bir ds species) are settled around a mow meadow and irrigated cultures (55 ha). The breeding site of tile Moroccan Locust is on the 2 hectares o f sheep-fold. The mean density of locusts egg pods was 77/m(2), of whi ch 37% was destroyed by Coleoptera larvae (Meloideae) and Diptera larv ae. Falco naumanni Fleicher and Pyrrhocorax pyrrhocorax docilis Gm. ar e important locust predators on the site. Choughs were observed probin g repeatedly in the soil to unearth egg pods and eat them. It is known that sheep create the conditions suitable for the Maroccan Locust to gregarise. We demonstrate that the strict time table of pastoral event s also influences the acridid population dynamics : young hoppers hatc h in May into an environment free from sheep disturbance and sheltered from predators until the hay is cut, Transhumance on the 28th July, i n the middle of the laying season, modifies space and food available t o the Acrididae.