caa a22 4500 386361401 CHVBK 20180307111916.0 cr unu---uuuuu 161130e198909 xx s 000 0 eng 10.4039/Ent121771-9 doi S0008347X00035665 pii (NATIONALLICENCE)cambridge-10.4039/Ent121771-9 COMPARISON OF LEAF DISC AND PETRI DISH ASSAYS FOR THE ASSESSMENT OF DICOFOL RESISTANCE IN POPULATIONS OF EUROPEAN RED MITE FROM SOUTHERN ONTARIO [Elektronische Daten] Two bioassay methods using leaf discs and Petri dishes as the treated medium were compared. Resistance levels were approximately 11-fold with the leaf disc method and 7-fold using the Petri dish assay. Comparisons of the two methods on six wild populations indicated that the Petri dish assay was more sensitive in identifying low frequencies of resistance. Advantages of the Petri dish assay over the previously used leaf disc method for rapid, field-type surveys are discussed. Surveys of populations from the Simcoe and Niagara areas, using the Petri dish assay, indicated resistance to dicofol in 11 of 22 samples. Resistance was generally correlated with sites where dicofol had been used at least once a year for 2-3 consecutive years. The data indicate a resurgence of dicofol resistance since 1984 when resistance was detected at 4% of the surveyed sites. Copyright © Entomological Society of Canada 1989 Pree D.J. Agriculture Canada Research Station, Vineland Station, Ontario, Canada L0R 2E0 Cole K.J. Agriculture Canada Research Station, Vineland Station, Ontario, Canada L0R 2E0 Fisher P.A. Ontario Ministry of Agriculture and Food, Horticultural Experiment Station, Simcoe, Ontario, Canada N3Y 4N5 The Canadian Entomologist Cambridge University Press 121/9(1989-09), 771-776 0008-347X 121:9<771 1989 121 TCE https://doi.org/10.4039/Ent121771-9 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.4039/Ent121771-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pree D.J. Agriculture Canada Research Station, Vineland Station, Ontario, Canada L0R 2E0 NATIONALLICENCE 700 1- Cole K.J. Agriculture Canada Research Station, Vineland Station, Ontario, Canada L0R 2E0 NATIONALLICENCE 700 1- Fisher P.A. Ontario Ministry of Agriculture and Food, Horticultural Experiment Station, Simcoe, Ontario, Canada N3Y 4N5 NATIONALLICENCE 773 0- The Canadian Entomologist Cambridge University Press 121/9(1989-09), 771-776 0008-347X 121:9<771 1989 121 TCE CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge