Résumé:
To better understand the trend of locust populations existing in southern Algeria during the calm periods
(recession), a study on the phase status of locust populations of Schistocerca gregaria in its natural biotope, was carried
out during the two years 2009 and 2010. To do this, morphometric measurements of 163 Locust individuals including 81
males and 82 females, from eight different biotopes, were performed. The mean values of morphometric ratios of Elytron
on Femur (E / F) and Femur on Cephalic capsule (F / C) in the 8 study sites fluctuate in males from 2.02 to 2.13 for the
E / F ratio and 3 65 to 3.95 F / C ratio. For females E / F varies between 2.09 to 2.15 and F / C varies between 3.83 to 4.03.
The comparison of the results related to E / F ratios and F / C with those of Dirsh (1953) and the report on their
morphometric abacus of Duranton and Lecoq (1990) showed that male and female populations that evolve in the biotopes
of both southern and central parts of the Algerian Sahara, for the two years 2009/2010 are mostly the Solitarious-transient
with a rare presence of purely solitary individuals and a total absence of gregarious individuals.
