Influence of temperature on the hatch of Heterodera avenae Woll. populations from Algeria

Two Algerian populations of Heterodera avenae originating from Cued Smar in a sub-humid coastal plain and from Tiaret in an inland semi-arid plain wer e subjected to different temperature treatments and juvenile emergence eval uated. These populations were compared with two populations, Fr1 and Fr4 fr om southern and northen France, respectively, which represent two ecotypes with respect to hatching cycles in response to temperature. The two Algeria n populations hatched over a wide range of constant temperatures (3 to 25 d egreesC) but differed in the times at which juveniles emerged from the cyst s. Simulation of seasonal temperature variations (from summer to autumn or winter and, conversely, from winter to spring or summer) demonstrated diapa use in these two populations, induced by higher temperature (20 and 25 degr eesC) treatments and broken subsequently by lower temperatures (3 and 7 deg reesC). Both Algerian populations of H. avenae represent the Mediterranean ecotype, with biological variations that may represent regional adaptations to more or less severe climatic conditions.