Evaluation of acaricide toxicity to the parasitic mite (Varroa destructor), honeybee workers (Apis mellifera L.) and their residues in honey and beeswax.

Evaluate the toxic effects of five acaricides on the parasitic mite ( Varroa destructor ) and honeybee workers ( Apis mellifera L.): Denfer 15% (Spirodiclofen), Kofex 24% (Spiromesifen), Metake 20% (Amitraz), Koloum super 24% SC (chlorfenapyr), and Abalon 1.8% (Abamactine). These conventional acaricides are cheap and easy to apply, but prolonged use causes Varroa mites to rapidly develop resistance, and bee products can become contaminated with residues of acaricides. The bioassay test was used to detect acaricides toxic effects. Spirodiclofen and Spiromesifen were the most toxic compounds to honeybee worker with LC 50 values of 0.923 and 1.195 ug/ml, respectively, after 5 days, but Amitraz, Chlorfenapyr, and Abamactine were the least toxic compounds to honeybees with LC 50 values of 1.752, 42.72, and 56.868 ug/ml, respectively, after 5 days. Amitraz, Spiromesifen and Spirodiclofen were the most toxic compounds on V. destructor with LC 50 values of 0.497, 0.888 and 2.014 ug/ml, respectively, after 4 h, but Abamactine and chlorfenapyr were the least toxic compounds on V. destructor with LC 50 values of 70.972 and 76.62 ug/ml, respectively, after 3 h. Varroa mite infestation rates decreased in brood (75.5% vs 67%) and adult honeybee workers (77.16% vs 100%) of colonies treated with Spiromesifen and Amitraz, respectively, when compared to only non-treated colonies. Detecting residuals of acaricides by HPLC in honey and beeswax revealed that they were contaminated with Amitraz and Spiromesifen residues, but that they did not exceed the MRLs established by EPA and European Commission guidelines.