A Preliminary Study on “Personalised Treatment” against Varroa destructor Infestations in Honey Bee (Apis mellifera) Colonies (original) (raw)
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Field trial of honey bee colonies bred for mechanisms of resistance against Varroa destructor
Apidologie, 2007
We compared colonies selectively bred for both hygienic behavior and Suppression of Mite Reproduction (HYG/SMR) with colonies bred solely for hygienic behavior (HYG) and unselected control colonies. Colonies were evaluated for strength, brood viability, removal of freeze-killed brood, honey production, mite loads on adult bees and within worker brood, and mite reproductive success on worker brood for two years in two locations. By autumn in both years, the HYG/SMR colonies had significantly fewer mites on adult bees and in worker brood compared to the control colonies, and the HYG colonies had intermediate mite populations. Contrary to expectation, there were no differences among the lines in mite reproductive success. Further studies are required to determine if the genes and neural mechanisms that regulate the SMR trait are the same or different from those regulating hygienic behavior.
Controlled Infestation of Honeybee Colonies with Varroa Destructor Females
Journal of Apicultural Science, 2019
The development of female Varroa destructor mites in the bee colonies was examined in the apiculture season through a developed research system in which bee colonies were experimentally infested with fifty V. destructor females. Differences in infestation rates were observed between the control group (C) and the infested group (E). The average number of female mites per colony was determined at 513 in group E and 261.6 in group C. Natural daily mortality reached 0.16 mites in group E and 0.09 mites in group C. In group E, the number of V. destructors increased 7.96 to 13.32-fold, subject to colony. The size of V. destructor populations increased at a higher rate in group E than in group C (F= 12.39, P= 0.047). At the end of the experiment, the percentage of infested honey bee workers was determined at 0.97% in group E and 0.46% in group C. The results of this study confirmed that V. destructor mites continue to proliferate rapidly in honey bee colonies, and that the population growth rate in bee colonies and apiaries has to be closely monitored due to growing levels of resistance to acaricides.
American Bee Journal, 2002
A computer model simulating varroa mite (Varroa destructorpreviously known as Varroa jacobsoni) infestation in colonies of honey bees (Apis mellifera) confirmed that, due to the preference of mites to invade drone (male) honey bee brood to reproduce, a very high proportion of the mite reproduction could occur in a relatively small amount of drone brood. Several regimes of sampling or removing drone bee pupae to estimate or remove numbers of varroa mites were simulated to compare their effectiveness. The model indicated that regular sampling of at least 100 drone pupae could provide the beekeeper with a useful warning of when numbers of varroa were approaching damaging levels. An infestation level of 15% of drone pupae would be a conservative threshold to indicate treatment was imminently required. The model indicated that significant reduction of mite numbers could be achieved either by very regular uncapping and removal of most of the natural drone pupae, or by trapping mites in artificially high numbers of drone pupae. The numbers of drone pupae required to significantly delay the mite build-up could be reduced considerably by trapping at a time when the bee colony was otherwise broodless. However, the varroa numbers were not controlled sufficiently by drone brood removal alone in any of the regimes tested.
Apidologie, 2006
We compared the mechanisms of resistance to Varroa destructor displayed by bees bred for Suppression of Mite Reproduction (SMR) and hygienic behavior (HYG). Mites from SMR and HYG source colonies were introduced into recently sealed SMR and HYG worker brood, and the infested pupae were placed either into recipient colonies or into an incubator. SMR colonies removed significantly more miteinfested pupae than the HYG colonies. The reproductive success (fertility and number of viable female offspring) of mites from both sources on pupae not removed by bees was significantly lower in SMR colonies. Within the incubator, the reproductive success of mites was also lower on SMR worker pupae, and lowest when mites from SMR colonies were introduced on SMR brood. Our findings indicated that bees bred for SMR express hygienic behavior; adult bees selectively remove pupae infested with mites. In addition, there is an effect of SMR pupae that reduces mite reproductive success that requires further investigation.
Controlled Infestation of Honeybee Colonies with Varroa Destructor Females
Journal of Apicultural Science
The development of female Varroa destructor mites in the bee colonies was examined in the apiculture season through a developed research system in which bee colonies were experimentally infested with fifty V. destructor females. Differences in infestation rates were observed between the control group (C) and the infested group (E). The average number of female mites per colony was determined at 513 in group E and 261.6 in group C. Natural daily mortality reached 0.16 mites in group E and 0.09 mites in group C. In group E, the number of V. destructors increased 7.96 to 13.32-fold, subject to colony. The size of V. destructor populations increased at a higher rate in group E than in group C (F= 12.39, P= 0.047). At the end of the experiment, the percentage of infested honey bee workers was determined at 0.97% in group E and 0.46% in group C. The results of this study confirmed that V. destructor mites continue to proliferate rapidly in honey bee colonies, and that the population growt...
Apidologie, 2015
The treatment against Varroa destructor has become a basic tool in beekeeping practices, mainly during autumn. The treatment effectiveness should be improved by identifying variables affecting the final outcome. The aim of this study was to identify the risk factors associated with the treatment outcome achieved during autumn control of Varroa destructor. The mite infestation after treatment was evaluated in 62 apiaries and data regarding management practices were collected by means of a questionnaire. A mixed-effects model was constructed to associate management variables with the risk of treatment failure occurrence. Colonies with high mite levels prior to treatment (P =0.002) and owned by beekeepers who did not frequently replace queens (P =0.001) were associated with a higher risk of treatment failure. Other beekeeping practices indirectly improved treatment effectiveness. An integrated strategy for controlling mites that includes chemotherapy and suitable beekeepers management is needed to keep mite populations low during winter.
Reproductive capacity of Varroa destructor in four different honey bee subspecies
Saudi Journal of Biological Sciences, 2019
Varroa tolerance as a consequence of host immunity may contribute substantially to reduce worldwide colony declines. Therefore, special breeding programs were established and varroa surviving populations investigated to understand mechanisms behind this adaptation. The aim of this study was to investigate the reproductive capacity in the three most common subspecies of the European honey bee (Carnica, Mellifera, Ligustica) and the F2 generation of a varroa surviving population, to identify if managed host populations possibly have adapted over time already. Both, singly infested drone and worker brood were assessed to determine fertility and fecundity of varroa foundresses in their respective group. We found neither parameter to be significantly different within the four subspecies, demonstrating that no adaptations have occurred in terms of the reproductive success of Varroa destructor. In all groups mother mites reproduce equally successful and are potentially able to cause detrimental damage to their host when not being treated sufficiently. The data further suggests that a population once varroa tolerant does not necessarily inherit this trait to following generations after the F1, which could be of particular interest when selecting populations for resistance breeding. Reasons and consequences are discussed. Ó 2019 Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Apidologie
Varroa destructor is a key contributor to honey bee (Apis mellifera L.) colony losses that threaten global economies. Some colonies, especially those displaying high levels of hygiene behaviour targeted towards V. destructor-infested cells, survive mite infestation. Worker bees displaying varroa sensitive hygiene (VSH) open infested brood cells and remove the contents, thereby suppressing mite reproduction. This study identifies features that distinguish cells uncapped by bees performing VSH from infested cells that VSH bees ignore. Brood cells targeted and uncapped by VSH bees were found to be more likely to contain multiple foundress females than nontargeted cells. They also contained higher numbers of mite offspring, and lay within brood cell patches that were more highly infested with V. destructor than were the surrounds of infested cells ignored by VSH bees. This study is the first to identify cell surrounds as a potential source of signals influencing the behaviour of bees performing VSH.
Possible host-parasite adaptations in honey bees infested by Varroa destructor mites
Apidologie, 2007
We investigated Varroa destructor mite population growth in a line of honey bee (Apis mellifera) colonies hat have survived mite infestation for seven years without treatment (Bond colonies), and in a line of colonies that had been treated to control the mites (Controls). We investigated if the source of mites affected mite population growth. The results showed that the overall mite population growth rate was reduced by 82% in Bond colonies compared to Control colonies, irrespective of the mite source (mites from Bond or Control colonies). Two traits may partly explain the difference seen in mite population growth. First, Bond colonies produced less worker and drone brood compared to Control colonies. Second, Control colonies had a larger proportion of the mites in the sealed brood compared to Bond colonies. Reduced brood production and traits leading to differences in mite distribution could be interpreted as adaptive responses to mite pressure, although a causal relationship was not demonstrated.
Effect of the honey bee subspecies on Varroa destructor population growth and brood infestation
The aim of the study was to check the effect of the honey bee subspecies on Varroa destructor population growth and on brood infestation by the parasite. The studies were carried out in 2009-2010. The following five subspecies of bees were tested: Carniolan bees represented by two lines, Kortówka and Dobra; Caucasian bees of the Woźnica line; Central European bees of the Augustowska line; crossbreeds achieved by the absorptive crossing of A. m. capensis with A. m. carnica drones selected for a short post capping period (PCP), bred at the Apiculture Division in Olsztyn. The coefficient of V. destructor population growth was similar in all groups, ranging from 1.3 to 1.5. The level of infestation of broods by Varroa destructor in all groups was also similar (17. .6%) and no statistically significant differences were noted. We conclude that the honey bee subspecies has no effect on parasite population growth.