Varroa contributes to the recent surge in honey bee colony losses. Varroa destructor .. Faktoren mit negativer Wirkung der Varroa-Milbe auf die Gesundheit der. Die Varroa-Milbe zählt weltweit zu den gefährlichsten Feinden der Bienen: innerhalb von ein bis drei Jahren kann sie ein Bienenvolk komplett. Default Watercolour Open Street Map. Varroa Status Natural Range. Leaflet | Map data © OpenStreetMap contributors, ODbL | Vector data © Crown Copyright.
|Author:||Miss Selina Reichel|
|Published:||28 September 2017|
|PDF File Size:||19.13 Mb|
|ePub File Size:||7.31 Mb|
|Uploader:||Miss Selina Reichel|
The Varroa milbe mite has been present for many years in most of the countries that are reporting an increase in colony losses at the moment. While mite populations can be controlled, one can still speculate that the losses can be varroa milbe, at least in part, to Varroa infestations in the colonies.
If so, what has changed regarding Varroa biology or the environment that can explain losses compared to 20 years ago?
Bienen-Parasit: Forscher entdecken Medikament gegen Varroa-Milbe
Potential reasons include changes in Varroa and host bee biology and population dynamics changes, Varroa control with varroa milbe, indirect effects of Varroa treatments and synergistic effects of multiple factors.
It has been shown that two major mite haplotypes have spread over the world, the Japanese and the Korean haplotypes Anderson,which might have different virulence depending on the haplotype Correa-Marques et al.
Each haplotype has a clonal genetic structure Solignac et al. While it varroa milbe unlikely that different Varroa haplotypes could explain the recent colony losses, varroa milbe new haplotypes of Varroa destructor were recently described in A.
Varroa World Distribution
Nothing is known about their virulence on European bees outside Asia, but those haplotypes might be a new threat to consider for A. Importation of bees from Asia should be considered carefully, since the impact of introducing Asian haplotypes to A.
The varroa milbe discovery of the Japanese haplotype in Spain makes it evident that HB market exchanges can disperse pathogens and parasites Varroa milbe et al.
Co-evolution of the host and the parasite is driven by mutations of both the mite and the bee, which can lead to a more or less stable equilibrium. Mite reproduction is an important trait in Varroa milbe population dynamics and differential reproduction rates had been observed since the first infestations on HB were detected Anderson, Changes in the host-parasite chemical ecology can influence Varroa populations and mite reproduction as the mite can be differentially attracted depending on inhibitory and stimulatory factors coming from different types of brood Nazzi and Milani, ; Trouiller and Milani, Population dynamics At the time of varroa milbe first introduction of Varroa in Germany, studies often found to mites in a colony 4 years after the initial infestation Ritter varroa milbe Perschil, ; Fries et al.
At that time, the economic threshold was determined to be fallen mites per day in July Ritter et al.
It is now unusual to find such high Varroa infestation levels. Today, German beekeepers are required to start treatment if the natural mite drop exceeds 10 mites per day, varroa milbe level that indicates the colony is close to collapse.
In Germany, a colony mite load above mites indicates the colony is close to collapse Boecking and Genersch, Interactions between viruses and Varroa mite infestation are key to understanding colony collapse as it has been shown that the bees can varroa milbe a higher Varroa load if they are not infested by viruses Martin, Sumpter and Martin worked on a model illustrating why varroa milbe mite levels associated with colony collapse exist.
As many viruses naturally infest HB colonies Gauthier et al.
varroa milbe When the mite arrived in Europe in the s, efficient control was rapidly deployed using bromopropylate, fluvalinate, amitraz and coumaphos in easy-to-use formulations. Inthe first occurrence of mite resistance to fluvalinate, a pyrethroid, was observed in Southern Varroa milbe, making the chemical compound unusable for Varroa control.
The mites have developed resistance to fluvalinate and to other pyrethroids like flumethrin Milani, ; Hillesheim et al.
Massnahmen zur Kontrolle und Bekampfung der Varroa-Milbe 
In spite of alternating among chemical controls, the mite became resistant to other miticides like coumaphos and amitraz as observed especially in the USA Milani, ; Elzen et al.
Treatments that kill susceptible individuals leave the more resistant mites to produce the next generation, and over time, the mite population becomes increasingly resistant.
Natural substances such as oxalic acid and thymol have not yet resulted in resistant mite populations, but while they reduce mite populations, they are not consistently highly effective in all situations. Varroa milbe lack of varroa milbe miticides to control Varroa lets the mite populations grow to injurious levels triggering colony collapse directly by the number of mites per bee or indirectly varroa milbe decreasing bee immunity and favoring virus multiplication.
Moreover, Varroa resistance to acaricides favors the escalation of chemical applications leading to increased doses and residues of miticides in the hive.