Pest Management Science (2012) 68, 348-354

Stefan Endepols, Nicole Klemann, Jens Jacob and Alan P. Buckle (2012)
Resistance tests and field trials with bromadiolone for the control of Norway rats (Rattus norvegicus) on farms in Westphalia, Germany
Pest Management Science 68 (3), 348-354
Abstract: BACKGROUND: The aim of this study was to determine the incidence and the level of resistance to bromadiolone among rats on farms suspected of being foci of resistance by using the international normalised ratio (INR)-based blood clotting response (BCR) test. Whether the level of reduced susceptibility constitutes 'practical resistance' was subsequently determined in field trials.
RESULTS: The 2.5 multiple of the ED₅₀ baseline was used to test for the incidence of resistance, and higher multiples in the range of the suspected resistance factor were used to investigate the degree of resistance. The ED₅₀ values of bromadiolone in resistant rats were confirmed in the range 4.70-7.05 mg kg⁻¹ for males and 4.62-6.61 mg kg⁻¹ for females. Variations within these ranges appeared between farms. According to the BCR resistance tests, 50-100% of rats were classified as resistant prior to the field trials; 29-100% of rats survived the treatments.
CONCLUSION: BCR tests based on the use of the INR and baselines are suitable for determining the incidence and for assessing the level of resistance in populations of Norway rats. The majority of rats of the Westphalian resistant strain, characterised by the Y139C marker in VKOR, are resistant to bromadiolone under practical control conditions.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Jens Jacob

Research topic(s) for pests/diseases/weeds:
pesticide resistance of pest
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Rattus norvegicus		Germany