Showing papers on "Varroa sensitive hygiene published in 2007"

What's killing American honey bees?

Abstract: On February 22, 2007, many Americans woke up to media reports that something was awry with their honey bees. A significant proportion of American beekeepers were complaining of unusually high rates of colony loss as their bees broke from their overwintering clusters. Loss of some colonies (say 10%) in early spring is normal and occurs every year. In 2007, however, losses were particularly heavy and widespread—beekeepers in 22 states (including Hawaii) reported the problem. Some beekeepers lost nearly all of their colonies. And the problem is not just in the United States. Many European beekeepers complain of the same problem. Moreover, beekeepers and researchers do not understand the specific causes of the losses.

Effects of parasitization by Varroa destructor on survivorship and physiological traits of Apis mellifera in correlation with viral incidence and microbial challenge

Abstract: Varroa mites (Varroa destructor) are serious ectoparasites of honey bees (Apis mellifera). This research addresses the impact of varroa mites on survivorship, viral incidence, and physiological traits of newly-emerged worker bees. RT-PCR confirmed our previous finding that varroa parasitization was linked to high levels of deformed wing virus (DWV). In non-treatment bees, varroa parasitization combined with increased viral levels altered survivorship curves from long-survival to shorter-survival types. After challenge with live Escherichia coli, the survivorship of mite-parasitized bees was significantly lower than mite-free bees. Deformed-wing, mite-parasitized bees died on average within 1 day, even without E. coli challenge. This was correlated with the absence of an important enzyme activity in insect immunity, phenol oxidase, lacking even in those bees challenged with immuno-elicitors. The lack of inducible phenol oxidase activity indicated that the bee immune system is not fully competent upon adult emergence. Varroa parasitism also significantly reduced body weight of the parasitized bees, but body weight was not significantly correlated with the survivorship of mite-parasitized bees. Our research indicates that the combination of mite parasitization, the interaction of DWV and microbes, and a developmental immune incompetency attribute to decreased worker survivorship and have a negative impact on colony fitness.

Bees with varroa Sensitive Hygiene preferentially remove mite infested pupae aged ≤ five days post capping

Abstract: *Summary Suppressed Mite Reproduction (SMR) is a trait of honey bees that provides resistance to Varroa destructor. The mechanism of resistance in SMR bees is the removal of infested pupae from capped brood, so a better name is VSH bees (acronym for Varroa Sensitive Hygiene). This study compared the removal of infested brood by VSH and control bees to determine whether VSH bees removed infested pupae of different ages at similar rates. A pair of infested combs containing all stages of pupae were transferred into each host colony (six VSH and six control colonies) for 40 hours. VSH bees removed significantly more (55%) infested cells (singly and multiply infested), than controls (13%). They removed significantly more (66%) singly infested pupae aged from one to five days post capping (cohort A) than did controls (16%). The two types did not differ in the removal of singly infested pupae aged five to 10 days post capping (cohort B) (5‐22%). Many pupae were found in uncapped cells at the end of the test, and most of the uncapped pupae were infested with mites. None of the uncapped cells contained prepupae, the development stage occurring during the first three days post capping. Thus, removal of infested pupae may be triggered by stimuli in cells with pupae aged 3‐5 days post capping.

Multitrophic interaction facilitates parasite–host relationship between an invasive beetle and the honey bee

Abstract: Colony defense by honey bees, Apis mellifera, is associated with stinging and mass attack, fueled by the release of alarm pheromones. Thus, alarm pheromones are critically important to survival of honey bee colonies. Here we report that in the parasitic relationship between the European honey bee and the small hive beetle, Aethina tumida, the honey bee's alarm pheromones serve a negative function because they are potent attractants for the beetle. Furthermore, we discovered that the beetles from both Africa and the United States vector a strain of Kodamaea ohmeri yeast, which produces these same honey bee alarm pheromones when grown on pollen in hives. The beetle is not a pest of African honey bees because African bees have evolved effective methods to mitigate beetle infestation. However, European honey bees, faced with disease and pest management stresses different from those experienced by African bees, are unable to effectively inhibit beetle infestation. Therefore, the environment of the European honey bee colony provides optimal conditions to promote the unique bee-beetle-yeast-pollen multitrophic interaction that facilitates effective infestation of hives at the expense of the European honey bee.

Analysis of varroa destructor infestation of southern african honeybee populations

Abstract: ___________________________________________________________________________ The discovery of the honeybee-specific ectoparasitic mite Varroa destructor in South Africa in October 1997 raised the spectre of massive honeybee colony losses as has occurred in most parts of the world where the varroa mite has been found. This was particularly concerning in Africa because of the importance of honeybees in the pollination of indigenous and commercial crops, and because of the numbers of small-scale beekeepers in Africa. The mite has now spread throughout South Africa and is found in almost all honeybee populations, both commercial and wild, and is also now present in most neighbouring countries. Varroa has not left a trail of destruction in South Africa as had been expected and no large scale collapse of the honeybee population occurred, despite the majority of beekeepers deciding not to protect their hives with chemical varroacides. Some colony losses did occur at the front of the varroa spread, and all colonies were found to be deleteriously affected by the mite which developed populations of 50 000 and more in some colonies. Infected colonies were also not as efficient as pollinators as uninfected colonies. Colonies exhibited all the same varroa effects witnessed in other parts of the world, with the exception that the majority of colonies did not die as a result of the infestation. The relative tolerance of African bees to the varroa mite has been confirmed by the longterm monitoring of both wild honeybee populations and commercial stock, and by population dynamic studies of the mites. In both wild and managed honeybee populations varroa appears to have been reduced to the status of an incidental pest. The development of mite tolerance took 3-5 years in the Cape honeybee (Apis mellifera capensis) and 6-7 years in the Savanna honeybee (Apis mellifera scutellata). The rapid development of mite tolerance in the Cape bee is thought to be due to the well developed removal of varroa-infested brood and the short post-capping period of worker brood. Together these resulted in a very rapid increase in infertile mites in the colony, the collapse of the mite population, and varroa tolerance. Tolerance does not develop as rapidly in Savanna honeybees as the post-capping period in these bees is similar to that of European bees and does not result in as many infertile mites. Nonetheless, varroa tolerance in Savanna bees develops more rapidly than would be the case in European bees because of more effective hygienic removal of varroa-infested brood. In both Cape and Savanna bees, the absence of varroacide applications and a “live-and-let-die” approach to the wild and commercial honeybee populations was crucial to the developed of population-wide varroa tolerance, in contrast to the selective breeding and pesticide treadmill practised in most parts of the world in an effort to get rid of the varroa mite. Varroa destructor is concluded not to be a serious threat to honeybees and beekeeping in Africa, and efforts should be made to prevent the use of pesticides and techniques that could hinder the development of natural mite tolerance in Africa.

Efficacy of strips coated with Metarhizium anisopliae for control of Varroa destructor (Acari: Varroidae) in honey bee colonies in Texas and Florida.

Abstract: Strips coated with conidia of Metarhizium anisopliae (Metschinkoff; Deuteromycetes: Hyphomycetes) to control the parasitic mite, Varroa destructor (Anderson and Trueman) in colonies of honey bees, Apis mellifera (Hymenoptera: Apidae) were compared against the miticide, tau-fluvalinate (Apistan®) in field trials in Texas and Florida (USA). Apistan and the fungal treatments resulted in successful control of mite populations in both locations. At the end of the 42-day period of the experiment in Texas, the number of mites per bee was reduced by 69-fold in bee hives treated with Apistan and 25-fold in hives treated with the fungus; however mite infestations increased by 1.3-fold in the control bee hives. Similarly, the number of mites in sealed brood was 13-fold and 3.6-fold higher in the control bee hives than in those treated with Apistan and with the fungus, respectively. Like the miticide Apistan, the fungal treatments provided a significant reduction of mite populations at the end of the experimental period. The data from the broodless colonies treated with the fungus indicated that optimum mite control could be achieved when no brood is being produced, or when brood production is low, such as in the early spring or late fall. In established colonies in Florida, honey bee colony development did not increase under either Apistan or fungal treatments at the end of the experimental period, suggesting that other factors (queen health, food source, food availability) play some major role in the growth of bee colonies. Overall, microbial control of Varroa mites with fungal pathogens could be a useful component of an integrated pest management program for the honey bee industry.

Comparison of Parasitic Mites in Russian-Hybrid and Italian Honey Bee (Hymenoptera: Apidae) Colonies across Three Different Locations in North Carolina

Abstract: The most economically important parasites of honey bee, Apis mellifera L. (Hymenoptera: Apidae), colonies are the parasitic mites Varroa destructor Anderson & Trueman and Acarapis woodi (Rennie). Research has shown that mite-tolerant stocks are effective means to reduce mite infestations within colonies, but it is unclear whether the stocks available commercially are viable means of mite control because they are likely to be genetic hybrids. We compared colonies of a standard commercial stock (“Italian”) with those of a commercially purchased mite-tolerant stock (“Russian”) for their levels of varroa and “tracheal” mites (A. woodi) over the course of 2 yr in three different geographic locations. We were unable to detect significant infestations of tracheal mites; thus, we were unable to adequately compare the stocks for their tolerance. In contrast, we found significant differences in the levels of varroa mites within and among colonies located across the three different study sites for both year...

Resistance of Varroa destructor to most commonly used synthetic acaricides.

Abstract: This review presents different aspects of Varroa destructor resistance to most commonly used contact acaricides. It is concerned with (1)--genetic background of the mechanism of this resistance, (2)--phenomenon of cross-resistance, (3) spread of discussed resistance throughout Europe and North America, (4)--methods of combating varroa resistance. The authors conclude that a rapid and sensitive DNA based test, enabling early detection of varroa resistance to pyrethroids and other contact acaricides is urgently needed.

Biotechnical methods in colony management, and the use of Apiguard® and Exomite™ Apis for the control of the varroa mite (Varroa destructor) in Irish honey bee (Apis mellifera) colonies

Abstract: SummaryThe benefits of incorporating biotechnical methods into honey bee (Apis mellifera L.) colony management for varroa (Varroa destructor Anderson & Trueman) control was evaluated. The effect of modifying bottom boards was determined by dividing the test colonies into three treatment groups: normal floor, mesh floor, and sticky floors. Invasion pressure was estimated by treating five colonies continuously with Bayvarol®. The effect of drone brood trapping as a method of reducing mite populations was examined by dividing the colonies into two test groups: colonies with and without (control) drone brood trapping. In the former, a shallow (super) frame was placed in the brood box. At three week intervals, the sealed drone brood was removed and the total number of sealed cells and viable varroa mites were counted. Brood area and honey bee population were also measured on each sampling date. Standard management practices were used throughout the season. The percentage efficacy of Apiguard® and Exomite™ Apis...

A comparison of the reproductive ability of Varroa destructor (Mesostigmata:Varroidae) in worker and drone brood of Africanized honey bees (Apis mellifera).

Abstract: Colony infestation by the parasitic mite, Varroa destructor is one of the most serious problems for beekeeping worldwide. In order to reproduce varroa females, enter worker or drone brood shortly before the cell is sealed. To test the hypothesis that, due to the preference of mites to invade drone brood to reproduce, a high proportion of the mite reproduction should occur in drone cells, a comparative study of mite reproductive rate in worker and drone brood of Africanized honey bees (AHB) was done for 370 mites. After determining the number, developmental stage and sex of the offspring in worker cells, the foundress female mite was immediately transferred into an uninfested drone cell. Mite fertility in single infested worker and drone brood cells was 76.5 and 79.3%, respectively. There was no difference between the groups (X2 = 0.78, P = 0.37). However, one of the most significant differences in mite reproduction was the higher percentage of mites producing viable offspring (cells that contain one live adult male and at least one adult female mite) in drone cells (38.1%) compared to worker cells (13.8%) (X2 = 55.4, P < 0.01). Furthermore, a high level of immature offspring occurred in worker cells and not in drone cells (X2 = 69, P < 0.01). Although no differences were found in the percentage of non-reproducing mites, more than 74% (n = 85) of the mites that did not reproduce in worker brood, produced offspring when they were transferred to drone brood.

Biocontrol of Varroa mites

Abstract: A biopesticide formulation using isolates of the fungus Beauveria bassiana has been developed, which can be used to control arachnid infestations of honeybee hives. The formulation is particularly useful for controlling infestations of Varroa destructor in honey bee hives.

The Occurrence of Varroa destructor Anderson and Trueman, 2000 on Honey Bees (Apis mellifera) in Turkey

Abstract: The mite formerly known as Varroa jacobsoni is one of the major problems in beekeeping worldwide. Recently, it was shown that this pest is not V. jacobsoni, which chiefly infests the nests of Apis cerana in the Malaysia-Indonesia region, and the widespread pest was recognized with the new name, V. destructor. Morphometric analysis was performed on collected Varroa specimens from various regions in Turkey and identified as V. destructor.

Strategy for ecologic control in fighting Varroa destructor

Abstract: The ectoparasite Varroa destructor is one of the most wide-spread parasites of the honey bee, which is increasing its resistence to traditional synthetic acaricides more and more with each year. New regulations on quality of the European Union ban the presence of residue in bee products, which rules out the use of chemical means in the course of the honey harvest. The concept of ecologic control of Varroa destructor in honey bee colonies implies the complementary use of adequate biotechnical and biophysical measures and treatments using preparations based on etheric oils and organic acids. The combination of these treatments according to the presented strategy makes it possible to keep varroasis under control.

Microbial control of varroa: misadventures in the field

Abstract: We report six different field trials testing the efficacy of Metarhizium anisopliae, an entomopathogenic fungus, against varroa mites in honey bee hives. Varroa mites are parasitic on honey bees and cause serious damage to Apis mellifera colonies. Several control methods are available for varroa mites, none are very effective, so new, more effective methods are being sought. Varroa has previously been shown to be highly susceptible to M. anisopliae infections, and in our first two field trials, we found some efficacy from spore applications. However, in subsequent field trials, we were not able to obtain any varroa control, despite attempting several different application methods, two different strains of the fungus, and testing in different climates and during different phenological states of the honey bee colony. We conclude that microbial control of varroa using fungi is not likely to be effective unless some way is found to prolong the survival of the spores (or other infective units) in the hive environment.

Reproduction of Varroa destructor in Africanized Honey Bees under the Tropical Conditions of Costa Rica

Abstract: Varroa destructor is a worldwide ectoparasite of serious economic importance for beekeeping. Severe colony mortality is routine in parasitized European honey bees (EHB) colonies in Europe, Asia and North America. This study was carried out in Heredia, Costa Rica. The reproductive ability of varroa mites was determined approximately 240 h after cell sealing in worker brood from four Africanized honey bee (AHB) colonies and four hybrid (HF1) colonies. Several variables were measured for foundress female mites: fertility, production of a mature female mite, production of only immature offspring, production of only female or only male offspring and no reproduction at all. No significant differences were found between AHB and HF1 in the percentage of fertile foundress mites (X 2 = 3.66, P= 0.06), the percentage of foundress mites that produced mature female offspring (X 2 = 0.53, P= 0.47), and the percentage of

Detection of the high risk pyrethroid resistant Varroa destructor mites in apiaries of the Warmia-Mazury province in Poland.

Abstract: Background . The aim of our current study was to investigate the possible occurence of pyrethroid (tau−fluvalinate) resistant Varroa mites infestations in 24 randomly chosen apiaries of Warmia−Mazury province of north−east Poland. Methods . The methodology used for the analysis of resistant Varroa strains strictly followed the pro - tocol described by Milani (6, 14). Results . We identified 3 apiaries that were infested with high risk pyrethroid resis - tance mites and a further 9 apiaries that were free from this resitance. The brood samples collected from the remaining apiaries did not contain sufficient numbers of parasites to enable us to properly perform the assay. Conclusions . Our finding that 25% of the tested brood samples showed a high risk of fully pyrethroid resistant Varroa mite contamina - tion indicates that resistant Varroa may become wide spread in apiaries in Poland. Interestingly these high risk resistant mites were found in honeybee colonies with low levels of Varroa infestation, with an average rate of 2.16%. We also discuss the role of amitraz (amidine) in the phenomenon of Varroa resistance to pyrethroids.