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REDUCED COLD-HARDINESS OF PEAR PSYLLA (HOMOPTERA: PSYLLIDAE) CAUSED BY EXPOSURE TO EXTERNAL WATER AND SURFACTANTS

Published online by Cambridge University Press:  31 May 2012

David R. Horton ,
Tamera M. Lewis  and
Lisa G. Neven
David R. Horton
Affiliation:
USDA-ARS, 5230 Konnowac Pass Road, Wapato, Washington, USA 98951
Tamera M. Lewis
Affiliation:
USDA-ARS, 5230 Konnowac Pass Road, Wapato, Washington, USA 98951
Lisa G. Neven
Affiliation:
USDA-ARS, 5230 Konnowac Pass Road, Wapato, Washington, USA 98951
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Abstract

Overwintering pear psylla, Cacopsylla pyricola (Foerster), were misted with water or with one of several dilute solutions of water and surfactant, and then exposed to a range of subzero temperatures for 24 h. Misted psylla had significantly greater mortality than unmisted controls. Increases in mortality occurred at temperatures as warm as −6°C, a temperature well within the range of conditions in the field. At extreme low temperatures (−18°C) there was virtually no mortality in the unmisted controls, whereas mortality approached or reached 100% in several of the misted groups. Temperatures necessary to kill 50% of insects estimated for topically treated psylla ranged between −2.6 and −12.7°C for surfactant-treated insects, and below −18°C for water-treated or control insects. The possibility of using surfactants and water for control of overwintering pear psylla is discussed.

Résumé

Des Psylles du poirier, Cacopsylla pyricola (Foerster), ont été vaporisées au cours de l’hiver, d’eau, ou alors d’une ou plusieurs solutions aqueuses de surfactants, puis exposées à une gamme de températures sous zéro durant 24 h. Les psylles vaporisées avaient des taux de mortalité plus élevés que les psylles témoins non vaporisées. L’augmentation de la mortalité a été constatée des températures pourtant assez élevées, jusqu’à −6°C, une température plus élevée que les températures minimales prévalant en nature. A température très froide (−18°C) la mortalité a été presque nulle chez les insectes témoins, alors qu’elle avoisinait 100% chez plusieurs des groupes vaporisés. Les températures nécessaires pour tuer 50% des insectes chez les psylles traitées par vaporisation se situaient entre −2,6 et −12,7°C dans le cas des insectes traités aux surfactants, et sous −18 °C chez les insectes vaporisés à l’eau et les insectes témoins. La possibilité de recourir à une vaporisation à l’eau et aux surfactants dans la lutte aux Psylles du poirier pendant l’hiver est examinée.

[Traduit par la Rédaction]

Type
Articles
Information
The Canadian Entomologist , Volume 128 , Issue 5 , October 1996 , pp. 825 - 830
Copyright
Copyright © Entomological Society of Canada 1996

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