Gas exchange rates of potted alfalfa, Medicago sativa L., grown under greenhouse conditions and infested with potato leafhoppers, Empoasca fabae (Harris), from an insectary culture were used to estimate reductions in photosynthesis and transpiration caused by infestations of 192, 120, 96, 72, 60, 36, 24, 12, and 0 leafhopper-hours, by caging 8, 5, 3, 1, or 0 insects on individual stems for 24 or 12 h. An exponential decay model fit the laboratory data, but halving exposure time doubled the decay coefficient, lambda. A cage effect was demonstrated by estimating increases in stomatal resistances that paralleled increases in the hours alfalfa was caged. Observed differences in lambda for the two exposures were attributed to this cage effect, but both measured values for lambda were different from zero. The nonzero slope of each line indicated that damage increased logarithmically with the density of leafhoppers. Quantified reduction in photosynthesis caused by these insects feeding under laboratory conditions will be useful in predicting yield loss in the field once the relationship between dry-matter production and photosynthesis is understood.
Document Type: Research Article
Publication date: April 1, 1984
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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.