Binomial sampling plans for the spotted alfalfa aphid, Therioaphis trifolii, in Argentina
| Autor: | Javier Gyenge, E. V. Trumper |
|---|---|
| Rok vydání: | 1998 |
| Předmět: | |
| Zdroj: | International Journal of Pest Management. 44:235-238 |
| ISSN: | 1366-5863 0967-0874 |
| DOI: | 10.1080/096708798228158 |
| Popis: | Binomial sampling plans were developed for Therioaphis trifolii (Monnell) (Homoptera; Aphididae), one of the most damaging insect pests of alfalfa crops in Argentina. During 1995, 50 stems from each of six alfalfa fields were sampled on each ofseven to ten occasions during the season. The mean (m), variance (S2) and the proportion of stems (PT) with no more than (T=) 0, 1…5 aphids were calculated. Aphid mean densities ranged from 0.02 to 82 individuals per stem. For each T, Ln(m) was regressed on Ln[-Ln(PT)], with R2 ranging from 0.87 to 0.94. Rearranging these equations, the empiricalrelationships between m and PT were obtained. The variance associated with the prediction of m from PT was incorporated in the development of binomial sampling plans for each T and in the calculation of sampling precision. At very low densities large sample sizes are required to estimate mean density with a given precison level. The minimum sample size decreases as mean density increases. However, above certain population le... |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|