Modified Drone-Brood Removal to Control Varroa destructor in Apis mellifera Colonies

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Title: Modified Drone-Brood Removal to Control Varroa destructor in Apis mellifera Colonies
Author: Wantuch, Holly Anne
Advisors: David Tarpy, Committee Chair
Wes Watson, Committee Member
Ed Vargo, Committee Member
Abstract: The parasitic mite Varroa destructor Anderson and Trueman (Acari: Varroidae) has plagued European honey bees (Apis mellifera L.) in the Americas since its introduction to the United States in the 1980s. For many years, these mites were sufficiently controlled using synthetic acaricides. Recently, however, beekeepers have experienced increased resistance by mites to chemical pesticides, which are also known to leave residues in hive products such as wax and honey. Thus, there has been increased emphasis on non-chemical IPM control tactics for Varroa. Because mites preferentially reproduce in drone brood (pupal male bees), we developed a treatment strategy focusing on salvaging parasitized drones and removing mites from them. In our initial study, we tested 10 colonies of honey bees in each of four treatment groups: 1) negative control (no treatment); 2) positive control (treatment with fluvalinate); 3) periodic drone-brood removal and freezing; and 4) periodic drone-brood removal and return of adult drones to colony after physically removing any mites. We found that there were no significant differences measured between the mean mite levels of the treatment groups (P> 0.05). However, there were numeric trends indicating that both drone-brood removal groups were intermediate in mite levels compared to the negative and positive controls. In a subsequent study, we removed drone brood from colonies in which there is no acaricidal application and banking it in separate “sacrificial†colonies treated with pesticides to kill mites emerging with drones. We tested 20 colonies divided into three treatment groups: 1) negative control (no mite treatment); 2) positive control (treatment with fluvalinate and thymol); and 3) drone-brood trapping. Two colonies were selected from the drone-brood trapping group to serve as sacrificial colonies. We found that drone-brood trapping significantly lowered mite numbers during the early months of the season, eliminating the need for additional control measures in the spring. However, mite levels in the drone-brood removal group increased later in the summer, suggesting that this benefit does not persist throughout the entire season. We recommend that drone-brood trapping can be utilized as an element of an integrated control strategy to control varroa mites. If implemented successfully, this method of drone-brood removal and rescuing may serve to eliminate a large portion of the Varroa population with limited chemical treatments, while simultaneously retaining any benefits of having adult drones in the colony.
Date: 2009-07-14
Degree: MS
Discipline: Entomology

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