| Drawf peach varieties, which were special peach in China, were chosen as the tested materials to evaluate the resistance to the green peach aphid (Myzus persicae Sulzer) in the field condition for two years. The structure of leaves of "Shoufen" and other varieties were observed under microscope and scanning electron microscope. The insecticidal activities of extracts from the leaves by different solvents were determined. The resistance mechanism of dwarf peach variety to the aphid was preliminarily studied. The results as followed:1. In the field and artificial inoculation condition, the aphid index of was 21.8 and 42.6, respectively, while the aphid index of "Zaofengwang" was 49.1 and 73.6, respectively. It was showed that "Shoufen" had a stronger resistance to the aphid than "Zaofengwang" and was a good resource with high resistance to green peach aphid.2. The repellent effect experiment results indicated that the number of aphid on the shoots of "Shouhong" and "Shoufen" was 11 and 15, respectively, much less than that of "Zaofengwang" and "Ruipan 4", which had 44 and 27, respectively. The dwarf peach variety had repellent effect on green peach aphid.3. LD50 value of extracts with ethanol from leaves of "Shoufen" and "Zaofengwang" to the aphid were 289.5mg/L and 2229mg/L, respectively. It was showed that the leaves of "Shoufen" had some toxic substances to the aphid.4. The villus on the underside cuticle of "Shouhong" and "Shoufen" were helical while those on "Ruipan 4" were slick and claviform. The villus was also found on the underside cuticle of "Ruiguang 27". The villuses were mostly distributed along the nervation. There was no villus on the underside cuticle of "Zaofengwang". There were no villus on the upside cuticle of all the five peach species.
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