Temperature, Plant-Growth Stage, and Insect-Population Effects on Seedling Survival of Resistant and Susceptible Alfalfa Infested with Potato Leafhoppers1
Seedling surviva1 of alfalfa, Medicago sativa L., after infestation with potato leafhoppers, Empoasca fabae (Harris), was a good criterion of resistance as measured by damage to plants in the field. The resistance of MSB- 11 (an experimental population selected for resistance to potato leafhopper yellowing in the field) exceeded that of Lahontan (a susceptible variety) in each of 3 seedling growth stages (cotyledon, unifoliolate, and trifoliolate) and at temperatures from 60 to 85.
Seedling mortality increased directly with temperature (60, 72) and insect-to-plant ratios (1:3, 1:2, 1:1), and inversely with age of seedlings (cotyledon, unifoliolate and trifoliolate). However, the interaction of plant-growth stages and insect populations was significant.
Insect-to-plant ratio, temperature, and plant-growth stage were critical in relation to detection of resistance and completion of test prior to egg hatch. Resistance differences were easily and consistently detected when alfalfa was infested at the unifoliolate stage with an insect-to- plant ratio of 1:2 under 1250 ft-c of light, a 16-hr photoperiod, and temperatures of either 65 or 75. At the lower temperature, typical reddening, yellowing, and stunting occurred and thus provided a basis for an additional resistance evaluation.
The resistance level of material tested necessitated the removal of the insects when resistance different were detectable to prevent killing of all seedlings in a test.
Document Type: Research Article
Publication date: February 1, 1968
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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.
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