Inventory of Varroa destructor susceptibility to amitraz and tau-fluvalinate in France
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Inventory of Varroa destructor susceptibility to amitraz and tau‑fluvalinate in France Gabrielle Almecija1,2 · Benjamin Poirot1 · Précillia Cochard1 · Christelle Suppo2 Received: 27 April 2020 / Accepted: 8 August 2020 © Springer Nature Switzerland AG 2020
Abstract Varroa destructor is one of the greatest threats for the European honeybee, Apis mellifera. Acaricides are required to control mite infestation. Three conventional chemical acaricide substances are used in France: tau-fluvalinate, flumethrin and amitraz. Tau-fluvalinate was used for over 10 years before experiencing a loss of effectiveness. In 1995, bioassay trials showed the first mite resistance to tau-fluvalinate. In some countries, amitraz was widely used, also leading to resistance of V. destructor to amitraz. In France, some efficiency field tests showed a loss of treatment effectiveness with amitraz. We adapted the bioassay from Maggi and collaborators to determine mite susceptibility to tau-fluvalinate and amitraz in France in 2018 and 2019. The lethal concentration (LC) which kills 90% of susceptible mite strains ( LC90) is 0.4 and 12 µg/mL for amitraz and tau-fluvalinate, respectively. These concentrations were chosen as the determining factors to evaluate mite susceptibility. Some mites, collected from different apiaries, present resistance to amitraz and tau-fluvalinate (71% of the mite samples show resistance to amitraz and 57% to tau-fluvalinate). As there are few active substances available in France, and if mite resistance to acaricides continues to increase, the effectiveness of the treatments will decrease and therefore more treatments per year will be necessary. To prevent this situation, a new strategy needs to be put in place to include mite resistance management. We suggest that a bioassay would be a good tool with which to advise the policymakers. Keywords Acaricide · Mite · Beekeeping · Honeybees · Resistance
Introduction European honeybees, Apis mellifera, have an important ecological and economic role with pollination of the natural ecosystem and crops and beekeeping. Honeybees, like many insects, undergo many threats such as the destruction and loss of habitat (Losey and Vaughan 2006; Zulian et al. 2013; Grab et al. 2019), the intensification of agriculture * Gabrielle Almecija [email protected] 1
APINOV, Research and Training Center, 10 rue Henri Bessemer, 17140 Lagord, France
2
Institut de Recherche sur la Biologie de l’Insecte, UMR 7621, CNRS-Université de Tours, 37200 Tours, France
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Vol.:(0123456789)
Experimental and Applied Acarology
with its increased use of pesticides (Goulson et al. 2015), the decrease of floral abundance (Baude et al. 2016) and the increasing number of invasive pathogens (Ryabov et al. 2017; Loope et al. 2019). For honeybees, one of the greatest threats is the ectoparasitic mite Varroa destructor (Anderson and Trueman 2000). The varroa mite is a natural ectoparasite of Apis cerana from Asia and moved to a new host, A. mellifera, during the twentieth century (Dieteman
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