LAUSR

A controlled, randomized, partially blinded study was conducted to evaluate target animal safety and efficacy of a late summer / autumn treatment with flumethrin 275 mg bee-hive strips (PolyVar yellow®, Bayer) against natural infestation with Varroa destructor in honey bee colonies. Thirty colonies received the test product applied as a “gate” at the hive entrance over 116 days, a positive control product (flumethrin bee-hive strips for in hive use, Bayvarol®) over 42 days or remained untreated as a negative control. On day 117 a follow-up treatment with coumafos solution (Perizin®) was applied to all three groups. For the efficacy evaluation dead mites were counted frequently up to 2 weeks after application of the follow-up treatment. For the safety evaluation dead bees were collected during treatment and follow-up treatment period by dead bee traps and several colony examinations were conducted until the following summer. Efficacy of the test product against Varroa was clearly demonstrated by a 99.9 % mite count reduction with superiority over the negative control (p = 0.0008). Survival of colonies treated with the test product or the positive control product was 80 % and 90 %, respectively, while survival in the negative control group was only 30 %. Significantly lower numbers of dead bees were observed in the treated groups compared to the negative control. Also, no differences in colony Original Article WAAVP_2017.indb 109 29.06.17 15:35 S110 EctoparasitEs EctoparasitEs development were observed between the groups that were considered clinically relevant. Thus, flumethrin 275 mg bee-hive strips were confirmed to be an efficacious and safe treatment for varroosis in honey bees caused by flumethrin-sensitive Varroa destructor.