News and Reviews

USDA Publications Recount Alfalfa Weevil Natural Enemy Introductions

In 1980, USDA-APHIS implemented a new program to redistribute alfalfa weevil parasites that had previously been imported from Europe by USDA-ARS scientists from 1957-1979. USDA Miscellaneous Publication No. 1504 (1993), Releases of Introduced Parasites of the Alfalfa Weevil in the United States, 1957-88, describes the detection surveys, rearing procedures, field collecting schemes, and field releases of the six natural enemies that were the focus of this program. There are only a few pages of text; the bulk of the 203 page book consists of tables of releases of introduced parasites by species and State. Although the tables are of limited value to the average person, there are several excellent color photographs of the wasps and weevils, and interesting maps show where each of twelve species was released and where it has been recovered.

There is more information on the parasitoids themselves in the similar USDA Production Research Report No. 167 (1976), Release and Recovery of Introduced Parasites of the Alfalfa Weevil in Eastern North America. Detailed descriptions are given for seven species that were introduced and established in eastern North America, including their biology and habits, as well as for five additional species that were released but never recovered.

Alfalfa Weevil Biological Control Extension Publication

The three page Iowa State University Extension Publication Pm-1484, Biological Control of the Alfalfa Weevil in Iowa, provides a good overview of biological control efforts against the alfalfa weevil in that state. There are brief descriptions of each of the five most important wasp parasitoids and the fungus Zoophthora phytonomi, as well as information on conserving these natural enemies. Excellent color photographs illustrate the weevil, some of the wasps, and fungus-infected weevil larvae.

Previous MBCN Articles on Alfalfa Weevil

If you're looking for additional information on biological control of alfalfa weevil, don't overlook some of the other articles on alfalfa weevil natural enemies previously printed in MBCN:

Documenting the Economic Impact of Alfalfa Weevil Natural Enemy Introductions

Many scientific articles have been written on the release and establishment of parasites of alfalfa weevil. Less common are articles that evaluate the biologic or economic impact of those releases. One such article on the biological control program's economic impact is "Economic Analysis of an Areawide Program for Biological Control of the Alfalfa Weevil" by J. M. White, P. G. Allen, L. J. Moffitt, and P. P. Kingsley in American Journal of Alternative Agriculture 10 (4): 173-179 (1995). The authors summarize the USDA's national biological control program, then describe their market-level economic analysis. They looked beyond the typical program costs, production costs saved and changes in crop yield, to how the program affects price and output of the crop, of other crops that could be grown in its place, and of livestock that consume the affected crops (this was written by economists, so there's some technical jargon). They showed overall expected economic benefits of $2.2 billion to alfalfa producers and consumers of livestock products from the USDA's alfalfa weevil biological control program--a benefit about 25 times the program cost. They caution that although this program was highly successful, not all areawide biological control programs will be as successful.

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