Sequential sampling for adult coccinellids in wheat

Autor: G. J. Michels, B. W. French, N. C. Elliot, R. W. Kieckhefer
Rok vydání: 1997
Předmět:
Zdroj: Entomologia Experimentalis et Applicata. 84:267-273
ISSN: 1570-7458
0013-8703
DOI: 10.1046/j.1570-7458.1997.00224.x
Popis: Adult aphidophagous coccinellids are important predators of cereal aphids in wheat in the Great Plains of the United States for which sampling methods are needed to facilitate improved management. An equation relating the mean number of adult coccinellids per m 2 in a wheat field to its variance was obtained using Taylor's power law. A sequential sampling procedure was developed to estimate the number of adult coccinellids per m 2 with constant average statistical precision (standard error/mean). The procedure was constructed by an equation relating the number of adult coccinellids per m 2 to the number of adult coccinellids per minute of counting incorporating into the Taylor's power law relationship. The procedure involves conducting a series of 1-min counts while walking through a field at a constant velocity of 10 m per minute. After each 1-min count sequential sampling stop-lines are consulted to determine if the specified level of precision has been achieved. Two methods, a statistical procedure and comparison with independent data, were used to assess the consistency with which the specified level of precision was achieved by the procedure. Results indicated that observed precision was close to that specified by the user over a wide range of adult coccinellid density.
Databáze: OpenAIRE
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