|
Titre :
|
Comparison of binomial and Iwao type sequential sampling plans for monitoring onion thrips (Thrips tabaci) [Thysanoptera:Thripidae] in onions.
|
|
Auteurs :
|
F. Fournier ;
G. Boivin ;
R. Stewart
|
|
Type de document :
|
article/chapitre/communication
|
|
Année de publication :
|
1994
|
|
Format :
|
69-78
|
|
Langues:
|
= Français
|
|
Mots-clés:
|
Echantillonnage
;
Echantillonnage sequentiel
;
Echantillonnage binomial
;
Simulation
;
Repartition spatiale
;
Thrips tabaci
;
Thysanoptera
;
Thripidae
;
Allium cepa
|
|
Résumé :
|
Transient differences in onion thrips (Thrips tabaci) densities were observed between the margins and the centre of some onion (Allium cepa) fields. Onion thrips populations consist in aggregates contagiously dispersed within onion fields. Two types of sequential sampling plans were established for T. tabaci in onions: a binomial plan based on the presence of 5 thrips plant(-1), and one of the Iwao type, requiring counts of all thrips present. Acceptation boundaries for these plans were calculated for economic thresholds of 0.9 and 2.2 thrips leaf(-1). Plans were validated in fields with thrips populations varying between 0.01 and 32.33 thrips leaf(-1). Binomial sequential sampling plans were found to be as reliable as plans requiring counts of all thrips, with an error rate not exceeding 4%, a level below the theoretical error rates of 5 and 10% used in the calculations. Correct decisions were reached in 90.4 and 83.6% of the situations with plans requiring counts of all thrips, and in 84.8 and 82.4% of the situations with binomial plans for economic thresholds of 0.9 and 2.2 thrips leaf(-1), respectively. The average number of samples needed to reach a decision varied between 10 and 14 plants according to the plan used. Use of binomial plans can save up to 62 and 88% of the counting effort for thresholds of 0.9 and 2.2 thrips leaf(-1), respectively.
|
|
Source :
|
Phytoprotection - 0031-9511, vol. 75, n° 2
|
![Comparison of binomial and Iwao type sequential sampling plans for monitoring onion thrips (Thrips tabaci) [Thysanoptera:Thripidae] in onions.](./styles/bel_inra/images/no_image.jpg)
