|Ryder, Edward - COLLABORATOR-USDA,ARS|
Submitted to: Eucarpia Conference on Lettuce and Leafy Vegetables
Publication Type: Proceedings
Publication Acceptance Date: January 23, 2003
Publication Date: March 19, 2003
Citation: In: Th. J.L. van Hintum, A. Lebeda, D.A. Pink & J.W. Schut (eds). Proceedings of the Eucarpia mtg. on leafy vegetables, genetics & breeding. Noordwijkerhout, the Netherlands, March 19-21, 2003. Centre for Genetic Resources, The Netherlands (CGN), Wageningen, The Netherlands, p. 43-47. Interpretive Summary: Leafminers are major insect pests of many important agricultural crops including lettuce and spinach. Resistant cultivars are the most economic means of insect control, but lettuce and spinach cultivars resistant to leafminers are not presently available. We evaluated 48 lettuce and 338 spinach varieties for insect resistance by releasing leafminer flies in an insect cage to feed on the plants. Resistant varieties with fewer leafminer stings or mines were found in cultivated lettuce and spinach as well as wild lettuce species, and the results wee confirmed in field experiments. We are currently using crossing, selection and other breeding techniques to transfer the leafminer resistance into different types of lettuce and spinach cultivars.
Technical Abstract: Leafminer (Liriomyza langei Frick) is a major pest that causes considerable damage to a wide variety of vegetable crops including lettuce and spinach. Forty-eight lettuce cultivars and introduction lines and 338 spinach accessions were screened in an insect cage for leafminer resistance. Significant genetic variation for leafminer stings per unit leaf area was observed among genotypes tested. Resistant lines with fewer leafminer stings were found in cultivated lettuce and spinach, Lactuca saligna, L. serriola, and L. virosa. The resistance in lettuce 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. Leaf miner resistant plants were selected in F2 progenies of such crosses, and were backcrossed to restore horticultural type. A phenotypic recurrent selection method was used to increase the level of leafminer resistance in spinach.