Submitted to: International Journal of Acarology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2003
Publication Date: 3/26/2004
Citation: Sammataro, D., DeGrandi-Hoffman, G., Ostiguy, O., Wardell, G., Finley, J. Testing a combination of control strategies to manage Varroa destructor (Acari: Varroidae) population levels in honey bee (Hymenoptera: Apidae) colonies. 2004. Inter. J. Acarology 30:71-76. Interpretive Summary: Mite populations at the end of the study did not differ among treatments or between sites. However, colony populations at Site 2 were significantly larger and overall colony survival was greater than at Site-1. Colony mortality during the winter following the study is shown in Table 2. At site-1,60% of the control colonies and 40% of the queen/strip treatment were dead by the end of the experiment. At Site 2, one colony in the queen/strip treatment was dropped out due to American Foulbrood Disease. Site 1 had far greater mortality than Site 2. At site 1, all the control colonies and 80% of the colonies with hygienic queens +T-02 strips died over the winter. Colony survival was greatest in colonies with hygienic queens and screen inserts regardless of whether they were treated with T-02 strips. At Site 2, no colonies were lost over the winter. The study demonstrates how the effectiveness of tactics to reduce the impact of Varroa on colony survival might ultimately depend upon the location of an apiary and how if affects the growth of colony populations.
Technical Abstract: A combination of tactics to reduce Varroa destructor population growth was tested in honey bee colonies located in two apiary sites. The tactics were: mite tolerant queen stock, screen inserts and T-02 strips (AI thymol). The effectiveness of the treatment combinations differed between the apiary sites. At Site 2, all colonies survived over the winter, while at Site-1, over-winter mortality of colonies was lowest in those exposed to a combination of hygienic queens and screen inserts. There were significant differences in mite drop among colonies following the T-02 strip treatments (Table 1). At both sites, colonies with hygienic queens and screen inserts had the lowest mite drops followed by the queen, + screen, + T-02 strips treatment. Colonies treated with T-02 strips having either hygienic queens or screen inserts did not differ in mite drop at either site. At Site 2 though, colonies with hygienic queens + screen inserts had significantly fewer mites drop than those with screen inserts and T-02 strips. Colonies with T-02 strips did not differ from controls at either site. There was no difference in colony populations among tteatments in either site (Site 1: F=l.64, d.f.+4,18, p=0.21; Site-2: F=0.40, d.f.=4,19,p=0.81), so we pooled data from all treatments in each site and tested for differences in colony size between sites using a t-test. Average colony populations estimated from combining all colonies at a site were greater at Site 2 than Site 1 (t=-3.14, d.f.=39, p=0.0032).