Interrelationship of Three Laboratory Screening Procedures for Breeding Alfalfa Resistant to the Alfalfa Weevil 1

Abstract

Seventy-five alfalfa varieties, synthetics, and ecotypes were evaluated in a study designed to: (1) evaluate the effectiveness of mass screening alfalfa in the cotyledon stage for isolating resistance to the adult and larval stages of the alfalfa weevil, (2) study possible relationships among plant reactions in laboratory [or adult feeding and larval development, and (3) search for sources of resistance to adult and larval feeding. Plants selected by a cotyledon feeding test were compared with unselected checks for resistance to adult leaf feeding and larval development. Plants selected by the cotyledon test had significantly less adult feeding and smaller larvae than did unselected plants of the same variety. Differences, however, were small. Some varietal differences were noted, but no entry had a high degree of resistance. Plants with some resistance were isolated in low frequency from most varieties.