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ANNO 1 Numero 2
Marco Lodesani [1], Norberto Milani [2], Giorgio Della Vedova [2], Silvano Calvarese [3], Orlando Campolo [4], Mario Colombo [5], Roberto Colombo [1], Gisella Cremonesi [5], Vincenzo Langella [3], Enzo Marinelli [6], Sergio Massi [1], Antonio Nanetti [1], Vincenzo Palmeri [4], Anna Gloria Sabatini [1], Giorgia Serra [1]

Monitoring of the presence of fluvalinate and coumaphos resistant strains of Varroa destructor in Italy

[1] Istituto Nazionale di Apicoltura, via di Saliceto, Bologna (I)
[2] Dipartimento di Biologia applicata alla difesa delle piante, Università di Udine (I)
[3] Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise “G. Caporale”, Teramo (I)
[4] Dipartimento di Agrochimica e Agrobiologia, Università di Reggio Calabria, Gallina (RC) (I)
[5] Istituto di Entomologia Agraria, Università di Milano (I)
[6] Istituto Sperimentale per la Zoologia Agraria, sez. di Apicoltura, Roma (I)

Resistance to acaricides is a serious problem in the chemotherapy of the mite Varroa destructor and can cause disastrous colony losses if the control of the mite relies on ineffective treatments. A national monitoring programme to determine the proportion of mites resistant to fluvalinate and coumaphos was carried out in 2003 in Italy. Fifty-four samples of mite were collected from eleven regions and assayed in the laboratory by using paraffin-coated capsules. With fluvalinate, survival at the diagnostic concentration expected to kill all susceptible mites (200 µg/g) exceeded 10% in 12% of the mite samples; with coumaphos (50 µg/g), it exceeded 10% in 44.4% of the samples. The proportion of resistant mites varied in different areas, probably depending on the use of these active ingredients in previous years; regarding fluvalinate, it was higher in Northern Italy, while it the opposite was true for coumaphos. A significant positive correlation was found between the levels of coumaphos residues in the wax and the survival of the mites collected from the same colony (n=30, R2=0.39, P<0.05) while no correlation was found for fluvalinate. The diffusion of resistant varroa populations highlights the importance and the urgent need for an integrated resistance management and for early detection of resistance through routine screening of varroa populations.

Contact: m.lodesani@stpa.unibo.it