Submitted to: Acta Horticulture Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/7/2003
Publication Date: 6/8/2004
Citation: Mou, B., Ryder, E.J., Tanaka, J., Liu, Y.B., Chaney, W.E. 2004. Breeding for Resistance to Leafminer in Lettuce. Acta Horticulturae. 2004. v. 637. p. 57-62. Interpretive Summary: Leafminer is a major pest that causes considerable damage to a wide variety of vegetable crops including lettuce. Resistant cultivars remain the most economic means of insect control. We screened 84 lettuce varieties for insect resistance by releasing leafminer flies in an insect cage to feed on the lettuce plants. The lettuce varieties showed great differences in the number of leafminer stings per unit leaf area, and those varieties with fewer stings are considered resistant to leafminers. Resistance was found in lettuce species Lactuca sativa, L. saligna, L. serriola, and L. virosa and the results were confirmed in a field experiment. We are using hybridization, selection, and other breeding techniques to transfer the leafminer resistance into iceberg, leaf, romaine, and butterhead lettuces.
Technical Abstract: Leafminer (Liriomyza langei Frick) is a major pest that causes considerable damage to a wide variety of vegetable crops including lettuce, and resistant cultivars remain the most economic means of insect control. Eighty-four lettuce cultivars and introduction lines were grown in an insect cage with eight replications for resistance screening. Leafminer flies were released in the cage to feed on the plants. Significant genetic variation for leafminer stings per unit leaf area was observed among genotypes tested. Resistant lines with fewer leafminer stings were found in Lactuca sativa, L. saligna, L. serriola, and L. virosa, and the resistance was confirmed in a field experiment. Crosses were made to combine leafminer resistance and superior horticultural traits in crisphead, green leaf, red leaf, romaine, and butterhead lettuces. Leafminer resistant plants were selected in F2 progenies of such crosses, and were backcrossed to restore horticultural type.