Potato genotypes and clones were evaluated for resistance (and antibiosis) to the green peach aphid Myzus persicae, in experiments carried out with potted plants using vases (no choice tests), in Jaboticabal, São Paulo State, Brazil. Sixteen genotypes were used in six experiments: 'Achat', 'Apuã', 'Aracy', 'Aracy Ruiva', 'Bintje', 'Ibitu Açu', 'Itararé', 'N 140-201', 'NYL 235-4', '288.719-13', '288.764-26', '288.776-3', '288.776-6', '288.794-19', '288.801-6' and '288.814-7'. In each experiment different combinations of these genotypes were used. In the first two experiments the plants were infested with 30 adults distributed in three leaves; after infestation three evaluations were done during the subsequent weeks. The third experiment was carried out arresting two adult females inside small cages fastened in the lower surface of the leaflets; the reproduction of the aphid was evaluated after seven days using two plantings. In the fourth experiment, 15 aphids were placed on each plant to evaluate the growth of the population, by counting the number of aphids/plant in three subsequent weeks. In the fifth experiment the number of nymphs/female was evaluated, while in the sixth experiment the nymphs weight was evaluated at the seventh day of life. The density of glandular trichomes was measured on lower laminar surface and on the main vein of mature leaves. The functionality of the glandular trichomes was also evaluated. The commercial genotype Ibitu Açu presented a high degree of antibiosis to M. persicae; the genotypes 288.776-3 and 288.794-19 also presented this mechanism of resistance, in moderate degree; '288.719-13' and '288.764-26' were also resistant to the green peach aphid, probably due to the presence of functional glandular trichomes, types A and B, in their leaflets (antixenosis). The commercial genotype Bintje and the clone 288.801-6 were the most susceptible.
Solanum tuberosum; Myzus persicae; host plant resistance; atixenosis; antibiosis
