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SPATIAL PATTERNS OF AND SAMPLING METHODS FOR WESTERN FLOWER THRIPS (THYSANOPTERA: THRIPIDAE) ON GREENHOUSE SWEET PEPPER

Published online by Cambridge University Press:  31 May 2012

J.L. Shipp
Affiliation:
Agriculture Canada Research Station, Harrow, Ontario, Canada N0R 1G0
N. Zariffa
Affiliation:
Agriculture Canada Research Station, Harrow, Ontario, Canada N0R 1G0

Abstract

Intra- and inter-plant spatial patterns were determined for adult and immature western flower thrips, Frankliniella occidentalis (Pergande), on greenhouse sweet pepper at two commercial greenhouses using five sampling methods. The population density of the thrips was monitored biweekly for 4 months from May to August using blue sticky-traps, plant tappings, blossoms, plant leaves, and whole plants. The intra-plant spatial patterns of adult and immature populations of F. occidentalis were aggregated with the majority of the thrips collected from the top one-third of the plant. The inter-plant spatial patterns also were aggregated. The aggregation cluster for the adult thrips was at least three plants in size, although it was surmised to be at the individual plant level for immature F. occidentalis. The accuracy of the blue sticky-trap, plant tapping, blossom, and leaf samples was determined for monitoring the population densities of adult and immature thrips throughout the growing season. It was shown that leaves should be sampled from the middle section of the sweet pepper plant when using this sampling method. A precision-level sampling program was proposed for monitoring adult F. occidentalis on greenhouse sweet pepper. Sampling blossoms was the most cost-effective sampling method based upon time and number of samples for a specific precision level.

Résumé

Cinq méthodes d’échantillonnage ont servi au cours d’une étude de la répartition spatiale, sur divers plants et sur un même plant, des adultes et des immatures du Thrips des petits fruits, Frankliniella occidentalis (Pergande), sur les poivrons verts de deux serres commerciales. La densité des populations de thrips a été évaluée deux fois par semaine durant 4 mois, soit de mai à août, par installation de pièges collants bleus, par frappement des plants et par récolte sur les fleurs, les feuilles et la plante entière. La répartition spatiale des adultes et des immatures de F. occidentalis sur un plant s’est avérée contagieuse et la majorité des insectes ont été récoltés dans le tiers supérieur de chaque plant. La répartition inter-plants était également contagieuse. Les groupes d’adultes occupaient au moins trois plants à la fois, mais on soupçonne que les immatures se regroupaient sur un seul plant. L’efficacité de chacune des méthodes d’échantillonnage (pièges collants, frappement des plants, récolte sur les fleurs, récolte sur les feuilles) pour mesurer la densité des populations de thrips adultes et immatures durant toute la saison de croissance a été évaluée. Les résultats ont révélé qu’il faut échantillonner les feuilles de la section médiane de chaque plant lorsqu’on utilise la méthode de récolte sur les feuilles. Un programme d’échantillonnage précis est proposé pour évaluer les populations d’adultes de F. occidentalis sur les poivrons verts de serre. C’est l’échantillonnage des fleurs qui offre le meilleur rapport efficacité-coût lorsqu’on tient compte du temps et du nombre d’échantillons requis pour atteindre un niveau de précision spécifique.

[Traduit par la rédaction]

Type
Articles
Copyright
Copyright © Entomological Society of Canada 1991

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