Screening of peanut cultivars for resistance to the lesser cornstalk borer, Elasmopalpus lignosellus (Zeller)

Abstract

A total of 490 peanut cultivars divided into sets of 16, were screened for possible resistance to the lesser cornstalk borer, Elasmopalpus lignosellus (Zeller). An objective greenhouse technique was developed for screening the plant material. A single seed was planted in a 6x3-in. cylinder which had been cut from a plastic sewer pipe. Each plastic container was placed 1 in. deep in the sand bed of a greenhouse bench. Plants were infested 1 week after planting using 3 first instar larvae per plant. Three weeks after infestation, the plants were rated for: (1) visual damage, (2) concealed damage, (3) instar rating, based on the insect stage of development at the rating time, and (4) survival rating, expressed as a percentage of the number of insects found. Since some plants died before the termination of the experiment, an index of plant survival was calculated for each cultivar. The variability to be expected from the technique, as measured with the use of the commercial variety Starr as a standard, fell within the acceptable biological limits. Based on the plant survival index, 41 cultivars were found to be very susceptible to the lesser cornstalk borer. In the material screened, 36 cultivars were selected as "resistant" and 45 as "promising candidates" based on the statistical analysis of the individual sets. Among the resistant cultivars were included the commercial varieties Early Runner, Va. Bunch 67, Florigiant and Florunner. Resistance was mainly due to the tolerance of these varieties to the borer attack. Cultivars chosen as resistant were re-evaluated to substantiate the original results. Results confirmed that both commercial and advanced agronomic cultivars possess some resistance to the lesser cornstalk borer. A laboratory method for studying and determining resistance due to antibiosis was also developed.