First detection of strains of Varroa destructor resistant to coumaphos. Results of laboratory tests and field trials

Free access article

Issue		Apidologie Volume 32, Number 1, January-February 2001


Page(s)		49 - 55
DOI		10.1051/apido:2001110

DOI: 10.1051/apido:2001110

Apidologie 32 (2001) 49-55

First detection of strains of Varroa destructor resistant to coumaphos. Results of laboratory tests and field trials

Massimo Spreafico, Francesca Romana Eördegh, Iris Bernardinelli and Mario Colombo

Istituto di Entomologia agraria, Milano University, Via Celoria 2, 20133 Milano, Italy

(Received 5 May 2000; revised 19 September 2000; accepted 28 September 2000)

Abstract
The susceptibility of four populations of Varroa destructor to the organophosphorous acaricide coumaphos was studied. The mites were taken from apiaries kept in Lombardy (northern Italy) and tested with a laboratory assay on paraffin wax with known concentrations of coumaphos. The susceptibility of two populations to coumaphos was close to that of susceptible populations, indicated in the literature (LC₅₀ at 24 hours: 12.6 $\mu$ g/g); a third population showed a significant, but slight increase in tolerance (LC₅₀ at 24 hours: 29 $\mu$ g/g) while the fourth population had a much higher LC₅₀ (>200 $\mu$ g/g at 24 hours). In subsequent field trials carried out in the apiary in which the latter population had been sampled, the total average efficacy of two treatments with Perizin^® (the commercial formulation of coumaphos) in colonies without capped brood was 46% (28-88% ).

Key words: coumaphos / Varroa destructor / resistance / bioassay / field trial

Correspondence and reprints: Massimo Spreafico
e-mail: colomar@mailserver.unimi.it and mario.colombo@unimi.it

© INRA, EDP Sciences, DIB, AGIB 2001

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.