Correlation between population size of pear Psylla (Cacopsylla chinensis) and leaf structure features in different pear cultivars

The feeding preference of pear psylla (Cacopsylla chinensis) varies among pear cultivars. To clarify whether leaf structural factors are related to C. chinensis resistance, eleven pear cultivars of three pear species and their hybrids in China were studied. The population size of C. chinensis in plots of different cultivars was investigated, and leaf paraffin sections of each pear cultivar were observed. Correlation analysis results showed that the thickness of palisade tissue (PT) and the thickness ratio (TR) of PT to leaf (L) were the main factors influencing resistance to C. chinensis. The leaves of cultivar Wujiuxiang and those species from France and the USA exhibited the thickest PT and the highest TR; these three cultivars demonstrated much higher resistance to C. chinensis than did the other cultivars. The cultivar Gold Nijisseiki, with a large C. chinensis population size, showed low PT and TR. The findings of this study may provide valuable information to pear growers, experts and scientists regarding plant protection, cultivation and breeding when selecting suitable varieties to culture from the perspective of pest control.