Free access
Volume 30, Number 5, 1999
Page(s) 383 - 395
Apidologie 30 (1999) 383-395
DOI: 10.1051/apido:19990504

Economic threshold for Varroa jacobsoni Oud. in the southeastern USA

Keith S. Delaplanea and W. Michael Hoodb

a  Department of Entomology, University of Georgia, Athens, GA 30602, USA
b  Department of Entomology, Clemson University, Clemson, SC 29634, USA

Abstract - This research was designed to determine economic thresholds for Varroa jacobsoni mites in mature overwintered colonies under conditions that encourage or discourage mite immigration. Congruent data from the present study and our earlier work suggest that a true late-season (August) economic threshold for mites in the southeastern USA lies within a range of mite populations of 3 172-4 261, ether roll mite levels of 15-38, and overnight bottom board insert mite levels of 59-187 in colonies with bee populations of 24 808-33 699. Overwintering colonies can benefit from an additional early-season (February) treatment. This benefit was realized in colonies which in February had the following average values: mite populations 7-97, ether roll 0.4-2.8, bottom board inserts 0.6-10.2 and bee populations 12 606-13 500. Continuous acaricide treatment never achieved colony bee populations or brood number significantly higher than in colonies treated more conservatively. There is evidence that minimizing mite immigration has the benefit of delaying the onset of economic thresholds. © Inra/DIB/AGIB/Elsevier, Paris

Key words: Apis mellifera / Varroa jacobsoni / integrated pest management / chemical resistance management