Rapid determination of the numbers of Varroa destructor, a parasitic mite of the honey bee, Apis mellifera, on sticky-board collection devicesNicholas W. Calderone and Sisi Lin
Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY 14853, USA
(Received 21 May 2001; revised 25 March 2002; accepted 18 April 2002)
We collected mites on boards coated with Vaseline; then, Vaseline, mites and debris were removed and solvent processed. Three weights were obtained for each sample: (1) weight after processing (pre-cleaned weight = W ); (2) weight after removing most remaining contaminants (partially cleaned weight = W ); and (3) weight after removing all remaining contaminants (clean weight = W ). The regression of the actual number of mites on W was significant ( P < 0.0001). Therefore, we evaluated the usefulness of W and W as surrogates for W because they are easier to obtain. Concordance correlation coefficients ( rc) for W with both W and W were < 0.80; therefore, correction factors for the two surrogates were calculated by dividing the average value of Wcln by: (1) the average value of Wpre, or (2) the average value of W . W and W were adjusted by multiplying them by the appropriate factor. The rc values for corrected data were > 0.99. Our method lets us obtain an accurate estimate of the number of mites in 20-30 min, regardless of the number present, and is useful when the number of mites on a board > 4 500. Our method also avoids the loss of precision that occurs with sub-sampling.
Key words: Varroa destructor / Apis mellifera / population estimation
Correspondence and reprints: Nicholas W. Calderone
© INRA, EDP Sciences, DIB, AGIB 2003