Free Access
Volume 32, Number 2, March-April 2001
Page(s) 127 - 138
DOI: 10.1051/apido:2001118

Apidologie 32 (2001) 127-138

Activity of oxalic and citric acids on the mite Varroa destructor in laboratory assays

Norberto Milani

Dipartimento di Biologia applicata alla Difesa delle Piante, Udine University, Via delle Scienze, 208 - 33100 Udine, Italy

(Received 7 July 2000; revised 9 December 2000; accepted 15 December 2000)

The toxicity of oxalic and citric acid to Varroa destructor Anderson and Trueman was studied with a laboratory assay. A contact test was used for the bioassay. Capsules were sprayed with solutions of the acids in a Potter tower and allowed to dry. Slight but significant differences in toxicity of oxalic acid were found among mites from different brood stages; the median lethal density for mites from pupae with white eyes was 1.49 $\mu$g/cm2. Citric acid was less toxic than oxalic acid. The addition of sucrose to oxalic acid made the material more hygroscopic and the mortality of the mites increased at 75% R.H. Glycerol showed a similar synergic activity irrespective of relative humidity.

Key words: Varroa destructor / bioassay / oxalic acid / citric acid / sucrose / glycerol / synergism

Correspondence and reprints: Norberto Milani

© INRA, EDP Sciences, DIB, AGIB 2001