caa a22 4500 386361908 CHVBK 20180307111918.0 cr unu---uuuuu 161130e198902 xx s 000 0 eng 10.4039/Ent121121-2 doi S0008347X0002856X pii (NATIONALLICENCE)cambridge-10.4039/Ent121121-2 LOCAL AND REGIONAL RESISTANCE TO FENVALERATE IN PSYLLA PYRICOLA FOERSTER (HOMOPTERA: PSYLLIDAE) IN WESTERN NORTH AMERICA [Elektronische Daten] Fenvalerate resistance was monitored in Psylla pyricola Foerster populations at 51 sites in Washington, Oregon, California, and British Columbia during early 1988. Resistance levels ranged from susceptible in an organic orchard in the Willamette Valley, OR, and at several other sites in Oregon and California, to highly resistant (> 100-fold compared with a susceptible strain) at several sites in central Washington. Generally, resistance levels were greater in the north than the south. In the Wenatchee and Yakima/Ellensburg, WA, areas, pyrethroid resistance was areawide, showing similar levels in both heavily treated and untreated orchards. In the Willamette Valley, OR, pyrethroid resistance was local and more consistent with the treatment histories of individual orchards. Factors influencing regional resistance appeared to be the species pool size of resistant and susceptible pear psylla, the intensity of spraying, and the unique host plant, life cycle, and dispersal attributes of this pest. Reasons for high regional resistance in central Washington and not in southerly areas are unknown, but this pattern is consistent with earlier patterns of insecticide resistance in pear psylla. The observed trends in fenvalerate resistance are discussed in relation to limiting resistance in pear psylla. Copyright © Entomological Society of Canada 1989 Croft B.A. Oregon State University, Corvallis, Oregon, USA 97331 Burts E.C. Oregon State University, Corvallis, Oregon, USA 97331 van de Baan H.E. Oregon State University, Corvallis, Oregon, USA 97331 Westigard P.H. Oregon State University, Corvallis, Oregon, USA 97331 Riedl H. Oregon State University, Corvallis, Oregon, USA 97331 The Canadian Entomologist Cambridge University Press 121/2(1989-02), 121-129 0008-347X 121:2<121 1989 121 TCE https://doi.org/10.4039/Ent121121-2 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.4039/Ent121121-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Croft B.A. Oregon State University, Corvallis, Oregon, USA 97331 NATIONALLICENCE 700 1- Burts E.C. Oregon State University, Corvallis, Oregon, USA 97331 NATIONALLICENCE 700 1- van de Baan H.E. Oregon State University, Corvallis, Oregon, USA 97331 NATIONALLICENCE 700 1- Westigard P.H. Oregon State University, Corvallis, Oregon, USA 97331 NATIONALLICENCE 700 1- Riedl H. Oregon State University, Corvallis, Oregon, USA 97331 NATIONALLICENCE 773 0- The Canadian Entomologist Cambridge University Press 121/2(1989-02), 121-129 0008-347X 121:2<121 1989 121 TCE CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge