A Seedling Test to Select for Alfalfa Weevil (Coleoptera: Curculionidae) Resistance in Alfalfa

A rapid method for evaluating alfalfa, Medicago sativa L., seedlings for alfalfa weevil, Hypera postica (Gyllenhal), resistance was developed for use in the laboratory. Seedlings were grown in greenhouse flats for 2 wk and tested for resistance to neonate alfalfa weevil larvae. Plants were infested at the rate of one larva per seedling. Seedlings were observed for feeding injury beginning on day 4 after infestation, and plants showing no or little damage in comparison with neighboring plants were selected for resistance. Seedlings of birdsfoot trefoil, Lotus corniculatus L.; large hop clover, Trifolium campestre Schreb.; and red clover, T. pretense L., which are resistant to the alfalfa weevil as mature plants, demonstrated resistance in this test. We concluded from this response that the method was sensitive enough to be used for selecting alfalfa seedlings for resistance to the alfalfa weevil. The method provides a rapid means for testing large numbers of plants for resistance at a relatively uniform stage of growth.