Field tests of the varroa treatment device using formic acid to control Varroa destructor and Acarapis woodi

Hood, W.M.chael; Mccreadie, J.W.

Journal of Agricultural & Urban Entomology 18(2): 87-96


The Varroa Treatment Device (VTD) filled with 85% formic acid (FA) was field tested for honey bee parasitic mite control in the Piedmont region of South Carolina from February-October, 1996. Three apiaries with 28 honey bee colonies were used in this test. Each colony was housed and managed in one, 10-frame Langstroth hive body and one 10-frame Illinois super. Two VTD/FA treatments, one Apistan(R) treatment and one control were replicated seven times for comparison of varroa and tracheal mite levels. Treatments were: (1) two 60-day treatments with the VTD/FA; (2) continuous VTD/FA treatment except during the 2-month nectar flow period; (3) two 42-day treatments with Apistan(R); and (4) VTD with sawdust but no FA as a control. Initial treatments were placed in colonies on 19 February, and the second treatments of VTD/FA and Apistan(R) were administered on 6 August. The VTD/FA treated colonies were serviced at approximately two week intervals during the treatment periods. Samples of approximately 300 adult bees were collected for mite diagnosis (alcohol wash method) on 23 January, 11 April, 10 June, 6 August, and 15 October. One hundred pupae from each colony were extracted and checked for varroa on the same dates beginning 11 April. Thirty-three adult bees from each sample were also diagnosed for tracheal mites by the thoracic disc method. Varroa mite counts on adult bees collected from all treatments were significantly less than the control for the August and October samples. Although varroa mite counts on extracted bee pupae from most treatments were significantly less than the control for the August sample, the Apistan(R) treatment was the only treatment that maintained significant varroa control in the brood for the October sample. Although the results of this test indicate that the VTD/FA is less effective than Apistan(R) in controlling varroa mites, the VTD/FA provides a viable alternative varroa mite control in combination with other mite control measures, especially as an early season treatment.