Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/2004
Publication Date: 3/20/2004
Citation: Mou, B., Liu, Y. Host plant resistance to leafminers in lettuce. Journal of the American Society for Horticultural Science. 2004. v. 129(3):383-388. Interpretive Summary: Leafminer is a major insect pest of many important agricultural crops including lettuce. Leafminer resistant traits were examined for 54 lettuce genotypes in insect cages and the field. The results from the field were highly correlated with the result from insect cages, suggesting that a cage test can be used to screen for resistance in the field. Wild lettuces had significantly fewer leafminer stings than cultivated lettuce. Among cultivated lettuces, leaf lettuce showed the lowest sting density and romaine types had the highest. The sting density trait was heritable. Results suggest both non-preference and toxic effect exist in lettuce germplasm, and resistant traits are stable whether leafminers have a choice of host plants or not. These findings suggest that breeding of lettuce for leafminer resistance is feasible.
Technical Abstract: Leafminer (Liriomyza spp.) is a major insect pest of many important agricultural crops including lettuce (Lactuca sativa L.). The goals of this study were to evaluate lettuce genotypes for resistance to leafminers and to estimate the heritabilities of leafminer-resistant traits in the field, to examine the association among different resistant traits, and to compare resistant genotypes under choice and no-choice condition. Fifty-four lettuce genotypes and 232 F2 plants of crosses were evaluated for leafminer stings and the production of pupae and flies in the field, and resistant genotypes were subjected to no-choice test. The sting results from the field were highly correlated (r = 0.756) with the results from insect cages, suggesting that a cage test can be used to screen for resistance in the field. Wild species (Lactuca serriola L., Lactuca saligna L., and Lactuca virosa L.) had significantly fewer stings than cultivated lettuce (L. sativa). Among cultivated lettuces, sting densities were lowest on leaf lettuce and highest on romaine types. Broad-sense heritability estimate for stings per unit leaf area in the field was 67.4%. The number of pupae produced per plant or per leaf was moderately correlated with sting density but was not correlated with leaf weight. Results suggest that both antixenosis and antibiosis exist in lettuce germplasm and resistant genotypes from choice test remain resistant under no-choice conditions. These findings suggest that genetic improvement of cultivated lettuce for leafminer resistance is feasible.