The spotted alfalfa aphid, Therioaphis maculate (Buckton), is attacked by three imported parasites in southern California. These parasites, Praon palitans Muesebeck, Trioxys utilis Muesebeck, and Aphelinus semiflavus Howard, were studied in three alfalfa fields in three distinct climatic areas in 1957. The roles of native coccinellids and fungus diseases (principally Entomophthora exitialis Hall & Dunn) in the biological control of the aphid were also evaluated. T. maculate was under heavy biotic pressure in all three fields over most of the year. In two of the fields, located at Cawelo and Lancaster, California, the aphid reached economic abundance on only one occasion. In the third field, located at Calexico, California, it did not reach economic status at any time during the year. Coccinellids appeared to play the most important role in the biological control of the aphid in all three fields. Disease of major importance at Calexico. Parasitization reached high levels in each of the plots at certain times and contributed significantly to the biological control of the aphid at each locality. The alfalfa harvesting process appeared to have an adverse effect on the parasites, particularly in midsummer. Periodic invasion of the study fields by large numbers of alate T. maculate had all unfavorable effect on the parasite- host ratio. The parasites seemed to show varying climatic adaptation. P. palitans was dominant at Cawelo and Lancaster, while T. utilis was dominant at Calexico. A. semiflvus was encountered in fair abundance at Cawelo only.
Document Type: Research Article
Publication date: February 1, 1959
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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.