Relative establishment rate and host preference of wooly apple aphid Eriosoma lanigerum (Hausmann, 1802)(Hemiptera: Aphididae) on promising apple hybrid rootstocks

The wooly apple aphid, Eriosoma lanigerum Hausmann (Hem.: Aphididae), is one of the main pests of apples all over the world. The purpose of this research was to investigate the host preference of wooly apple aphids toward 10 selected genotypes among the promising offspring obtained from hybridization and free pollination of indigenous apple genotypes (Azaish Isfahan and Marbai Mashhad) as maternal parent, and commercial apple cultivars (M9, M27, B9) as a paternal parent. This project was carried out during 2020 to 2022. The colonies of wooly apple aphids were monitored every 2 weeks from the beginning of April to November. Relative establishment rate and aphid preference index were calculated. Vegetative traits including percentage of rooting, number of roots produced, length of the rooting zone on stems, length of roots and number of stems produced were measured. In order to differentiate the hybrids, the cluster analysis method and the degree of effect of different traits on the indices were investigated through correlation analysis. The average establishment rate and preference index were 2.42±0.14 and 0.96±0.06, respectively. The most insensitive and the most sensitive hybrid base were Azop3(1386) and M9op3, respectively. Some of the vegetative characteristics of the hybrid rootstocks, including the average length of the productive root of the line have been effective in the occurrence of differences in the studied apple hybrid rootstocks in terms of establishment rate and host preference of wooly apple aphid. The results of this research are used in the future improvement programs of apple cultivars.