Apidologie 32 (2001) 127-138
Activity of oxalic and citric acids on the mite Varroa destructor in laboratory assaysNorberto 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 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