Performance of hygienic honey bee colonies in a commercial apiary

Apidologie, Jan 1998

Marla Spivak, Gary S. Reuter

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Performance of hygienic honey bee colonies in a commercial apiary

Performance of hygienic honey bee colonies in a commercial apiary Spivak 0 ry S. Reuter 0 0 Department of Entomology, 219 Hodson Hall, University of Minnesota , St. Paul, MN 55108 , USA - Colonies with naturally mated queens from a hygienic line of Italian honey bees (Apis mellifera ligustica) were compared to colonies from a commercial line of Italian bees not selected for hygienic behavior. The following characteristics were compared: rate of removal of freeze-killed brood; amount of chalkbrood; incidence of American foulbrood; honey production; and the number of mites, Varroa jacobsoni, on adult bees. The hygienic colonies removed significantly more freeze-killed brood than the commercial colonies, had significantly less chalkbrood, had no American foulbrood, and produced significantly more honey than the commercial colonies. Estimates of the number of Varroa mites on adult bees indicated that the hygienic colonies had fewer mites than the commercial colonies in three of four apiaries. In previous studies on the relation between hygienic behavior and resistance to diseases and mites, the test colonies contained instrumentally inseminated queens. This is the first study to evaluate hygienic stock in large field colonies with naturally mated queens. © Inra/DIB/AGIB/Elsevier, Paris Apis mellifera / hygienic behavior / Varroa / chalkbrood / American foulbrood - 1. INTRODUCTION For over 50 years, honey bee hygienic behavior has been recognized as an important mode of resistance to American foulbrood disease (AFB) [ 12 ]. Woodrow and Holst [ 24 ] stated,"... resistance to American foulbrood consists of the colony’s ability to detect and remove diseased brood before the causative organism, Bacillus larvae White, reaches the infectious spore stage". Over 14 years ago, it was determined that hygienic behavior also is a mechanism of resistance to chalkbrood, caused by the fungus Ascosphaera apis (Maassen ex Claussen) Olive and Spiltoir [ 5 ]. Recently it has been demonstrated that hygienic bees detect and remove pupae infested with the parasitic mite, Varroa jacobsoni Oudemans [ 1, 2, 13, 18 ]. The removal of infested pupae interrupts the reproductive cycle of the mite [ 4, 14 ]. However, the extent to which the behavior actually reduces the mite-load in infested colonies remains to be determined. Hygienic behavior occurs in approxi mately 10 % of most commercial honey bee populations thus far surveyed in the US (Spivak, unpublished observations). Despite the potential advantages of maintaining hygienic honey bee lines, few queen producers select for hygienic behavior. Rothenbuhler [ 16 ] postulated that the behavior is controlled by two independently assorting, recessive genes: one for uncapping the diseased brood (u) and one for removing diseased brood from the nest (r) (but see Moritz [ 10 ]). When colonies were composed of mixtures of hygienic and non-hygienic bees (progeny of instrumentally inseminated queens from inbred lines), Trump et al. [ 23 ] concluded that "for removal of all dead brood from a small colony, the proportion of the bees that must be of the hygienic type is higher than 13 % but less than 50 %". These early experiments suggested that a small percentage of bees, possibly within particular patrilines, may actually perform the behavior. The genetics of the trait may be controlled by raising queens from hygienic colonies and instrumentally inseminating them with semen from drones of other hygienic colonies [ 5 ]. However, instrumentally inseminated queens are used only as breeder stock in the beekeeping industry; commercial beekeepers use naturally mated queens in their production colonies. Genetic control may be obtained by saturating the mating area with hygienic drone mother colonies [ 8 ]. If lines of bees selected for hygienic behavior are to be utilized by the beekeeping industry, it is first necessary to examine colonies with queens reared from hygienic stock and mated naturally with unselected drones. Do colonies with naturally mated queens reared from a hygienic line remove freeze-killed brood more rapidly than commercial colonies? Do they have lower incidences of chalkbrood and AFB? Do they have fewer Varroa mites? And importantly, do they produce as much honey? The present study is the first to address these questions in a commercial apiary. 2. MATERIALS AND METHODS 2.1. Hygienic breeding stock The hygienic queens used in the experiment were bred from ’Starline’ stock, derived from Italian Apis mellifera ligustica Spinola, and were maintained at the University of Minnesota. The degree of hygienic behavior was determined by a freeze-killed brood assay in which the time was recorded for colonies to detect, uncap and remove brood from a 5 cm x 6 cm comb section (containing approximately 100 capped larvae and pupae per side of the comb) that had been cut from a frame within the brood nest of the same or different colony, frozen at -20 °C for 24 h, an (...truncated)


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Marla Spivak, Gary S. Reuter. Performance of hygienic honey bee colonies in a commercial apiary, Apidologie, 1998, pp. 291-302, Volume 29, Issue 3, DOI: doi:10.1051/apido:19980308