The reaction of four alfalfa varieties―Lahontan, Moapa, African, and Caliverde―of three ages of the plants was examined during a prolonged, severe, induced attack of the spotted alfalfa aphid (Therioaphis maculata (Buckton)). Increased plant age significantly decreased mortality of resistant varieties Lahontan and Moapa, but had no effect on that of Caliverde except at the shorter exposure period of 9 days. Older plants of African, a more tolerant but susceptible variety, survived slightly longer than the younger seedlings. About half the seedlings of Lahontan and Moapa infested in the cotyledon stage and about one-fourth of those in the second or third trifoliolate leaf stage were killed after 21 days' exposure to the increasing aphid population. Very low mortalities (0% and 3%) were recorded for plants 41 days old when infested. African at all age groups was more tolerant than Caliverde, which was killed in 21 days. The higher survival of Lahontan and Moapa, despite high aphid populations, indicated that tolerance as well as antibiosis contributed to their over-all resistance.
Document Type: Research Article
Publication date: February 1, 1960
More about this publication?
Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.