PATTERNS IN-FLIGHT PHENOLOGY OF A MIGRANT CEREAL APHID SPECIES

1. Flight phenologies of the migrant cereal aphid Rhopalosiphum padi, as indicated by suction trap catches throughout France between 1978 an d 1988, were compared using multivariate methods. 2. Cluster analysis identified seven main patterns of flight phenology for this species. 3 . Discriminant analysis of patterns using monthly mean temperatures al lowed the effect of weather on patterns of flight phenology to be iden tified. 4. The range of life-cycle strategies displayed by R. padi in France can explain partially the different types of patterns and their variations in space and time. 5. In the regions characterized by a ba lance between holocycly and anholocycly, the annual variability of pat terns in flight phenologies decreases with the increasing prevalence o f holocycly. 6. Temperature plays a more important role for the predic tion of likely patterns when a high proportion of the population is an holocyclic. 7. The biological status of R. padi, and therefore the bio logical functions of migrations, have to be specified to improve inter pretation of phenological analysis in pest forecasts relating to the s pread of barley yellow dwarf virus in winter cereal crops.