DOI: 10.1051/apido:2001133

Apidologie 32 (2001) 333-340

Acaricidal effect of oxalic acid in honeybee (apis mellifera) colonies

Ales Gregorc^a and Ivo Planinc<sup>b

a</sup>  Veterinary Faculty of the University of Ljubljana, Gerbicleva 60, 1000 Ljubljana, Slovenia
^b  Animal health centre of Slovenia, Dept. of bee health, Slovenia

(Received 30 May 2000; revised 14 March 2001; accepted 2 April 2001)

Abstract
Three oxalic acid (OA) solutions were applied to 24 honeybee colonies to test acaricidal effects on Varroa destructor . Daily natural mite drop per colony averaged 0.52. Higher mite mortality (18.33) was found after three August OA treatments. The mean efficacy's of the three water solutions of OA/sucrose (w/w), 3.4% /47.6% , 3.7% /26.1% , and 2.9% /31.9% applied in the presence of brood, was 52.28% , 40.66% and 39.16% respectively. A significantly higher efficacy was recorded when 3.4% /47.6% was applied in comparison to 2.9% /31.9% solution. There was no difference in efficacy between OA solutions administered during a broodless period on October 28. The average efficacy in all colonies was 99.44% . The results suggest that OA has limited acaricidal effect in colonies with brood, but it is highly effective in a broodless period.

Key words: Varroa destructor (jacobsoni) / honeybee / control / oxalic acid / efficacy

Correspondence and reprints: Ales Gregorc
    e-mail: GregorAl@mail.vf.uni-lj.si

© INRA, EDP Sciences, DIB, AGIB 2001