COMPARISON OF 2 METHODS, BASED ON COUNTS AND DAMAGE SYMPTOMS, TO ASSESS POPULATION-DYNAMICS OF THE LEAF-CURLING PLUM APHID BRACHYCAUDUS-HELICHRYSI (HOM., APHIDIDAE) ON SUNFLOWER

The population dynamics of Brachycaudus helichrysi on sunflower were d escribed during 3 years using principal component analyses. The relati onship between the dynamics of aphid numbers and the dynamics of the i ntensity of the leaf-curling symptom, described with a scale from 1 to 5, is discussed. For a given year and cultivar, there was good concor dance between the two dynamics. Four sunflower cultivars were compared in the same natural conditions. There were differences between cultiv ars with respect to their aphid infestations and the expression of the leaf-curling symptoms. Pest management can often be simplified by bas ing it only on the survey of leaf-curling symptoms.