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Varroosis is the most destructive disease of honey bees worldwide, inflicting much greater damage and higher economic costs than all other known apicultural diseases. The disease pattern of Varroosis is not uniform, as both the rate of infestation and secondary infections determine the clinical symptoms. Brood and adults bees are impaired. The mite injures the bee through repeated intake of hemolymph with her chelicerae while the host is in the larval, pupal and adult stage. The loss of hemolymph negatively effects the organ development of the bee. Colonies infested by V. destructor develop the parasitic mite syndrome and ultimately collapse if left untreated. Favourable reproduction conditions in the new host A. mellifera, the increasing impact of secondary infections (viruses) and the lack of coordinated and comprehensive treatment strategies and control methods that are often implemented too late or unsuccessfully by the beeA C H T U N G T R E N N U N G keeper result in reappearing wide spread colony losses. A viral infection vectored by V. destructor obviously increases its impact on colony collapses with the cause of this ongoing crisis. Varroa control should be a natural part of a beeA C H T U N G T R E N N U N G keeper's operation and flow into a system of Varroa control. The residues from Varroacide applications which are detectable today are all below the permitted maximum values. Although these minor detectable residues pose no threat to the consumer, they must be avoided in bee products, as honey possesses a very positive image in the mind of consumers.Zusammenfassung: Die Varroose ist derzeit die zerstörerischste Bienenkrankheit weltweit und verursacht höhere wirtschaftliche Verluste als alle anderen bekannten Bienenkrankheiten. Das klinische Erscheinungsbild der Varroose ist nicht einheitlich ausgeprägt, da sowohl die Befallsrate als auch Sekundärinfektionen die klinischen Symptome bestimmen. Bienenbrut und erwachsene Bienen werden geschädigt. Während der Larven-, Puppenund der imaginalen Bienenphase schädigt die Milbe ihren Wirt durch wiederholte Anstiche und Hämolympheentzug. Der Verlust an Hämolymphe beeinflusst die Organausbildung der Biene. In Varroa infizierte Völker entwickelt sich das "parasitische Milben-Syndrom" und führt letztlich zum Völkerzusammenbruch, wenn eine Behandlung unterbleibt. Günstige Reproduktionsbedingungen beim neu erworbenen Wirt A. mellifera, der zunehmende Einfluss von Sekundärinfektionen (insbesondere Viren), und unzureichende imkerliche Varroa-Bekämpfungsmaßnah-men führen immer wieder zu großflächigen Völkerverlusten. Virusinfektionen, die durch die Varroa-Milbe übertragen werden, scheinen zunehmenden Einfluss auf das Völkerverlustgeschehen zu nehmen. Varroa-Bekämpfung sollte integraler Bestandteil der normalen imkerlichen Betriebsweise sein und sich als Bekämp-fungskonzept darstellen. Varroazid-Rückstände sind heute nur in geringfügigen Konzentrationen (ppm) in den Bienenprodukten nachweisbar und sind vollkommen unbedenklich für den Konsumenten. Sie sollten aber weitg...

Sacbrood virus (SBV) infects larvae of the honeybee (Apis mellifera), resulting in failure to pupate and death. Until now, identification of viruses in honeybee infections has been based on traditional methods such as electron microscopy, immunodiffusion, and enzyme-linked immunosorbent assay. Culture cannot be used because no honeybee cell lines are available. These techniques are low in sensitivity and specificity. However, the complete nucleotide sequence of SBV has recently been determined, and with these data, we now report a reverse transcription-PCR (RT-PCR) test for the direct, rapid, and sensitive detection of these viruses. RT-PCR was used to target five different areas of the SBV genome using infected honeybees and larvae originating from geographically distinct regions. The RT-PCR assay proved to be a rapid, specific, and sensitive diagnostic tool for the direct detection of SBV nucleic acid in samples of infected honeybees and brood regardless of geographic origin. The amplification products were sequenced, and phylogenetic analysis suggested the existence of at least three distinct genotypes of SBV.

The hygienic behaviour of the honey bees is considered to be a potential characteristic associated with resistance to Varroa destructor n.sp. In this study the heritability of the hygienic behaviour of Apis mellifera L. bees was estimated on the basis of the mother±daughter regression. Data were obtained from measurements of the bees' hygienic behaviour towards V. destructor-infested cells and towards pin-killed sealed brood. The heritability for the hygienic behaviour towards V. destructorinfested brood cells was h 2 0.18 (+ 0.27) and h 2 0.36 (+ 0.30) for the hygienic behaviour towards dead brood cells. The repeatability was likewise higher for the pin-killed brood assay (W 0.46) compared with the assay using living mites-infested brood cells (W 0.24). The genetic correlation between the behavioural responses to either the mite-infested or pin-killed brood cells was calculated to be r g 0.61 (+ 0.51) and the phenotypic correlation to be r p 0.11 (p 0.28, n 100). Since hygienic colonies demonstrate resistance to brood diseases such as American foulbrood and chalkbrood, it may be worthwhile to intensify the expression of the hygienic behaviour through selective breeding and thus strengthen these potential characteristics associated with resistance to V. destructor in honey bee stock. ZusammenfassungHeritabilita È t des Varroa-spezi®schen Hygieneverhaltens der Honigbienen (Hymenoptera:Apidae) Dem Hygieneverhalten der Honigbienen wird als potentieller Varroa-Toleranzfaktor besondere Beachtung geschenkt. In dieser Untersuchung wurde ± auf der Basis der Mutter-Tochter-Regression ± die Heritabilita Èt des Hygieneverhaltens von Apis mellifera L. ermittelt. Als Datengrundlage dienten Quanti®zierungen des Hygieneverhaltens der Bienen gegenu È ber mit Varroa destructor n.sp. in®zierter und gegenu È ber toter (`genadelte') gedeckelter Bienenbrut. Der daraus ermittelte Heritabilita Ètswert lag fu È r das Hygieneverhalten gegenu È ber mit Varroamilben in®zierter Brut bei h 2 0.18 ( + 0.27) und bei h 2 0.36 (+ 0.30) fu È r das Hygieneverhalten gegenu È ber toter Brut. Auch die Wiederholbarkeit war a Èhnlich ho È her bei dem Hygieneverhalten gegenu È ber toter Brut (W 0.46) im Vergleich zu W 0.24 ermittelt am Hygieneverhalten der Bienen gegenu È ber experimentell mit lebenden Milben in®zierten Brutzellen. Die genetische Korrelation zwischen diesen Verhaltensreaktionen wurde als r g 0.61 (+ 0.51) errechnet und die pha Ènotypische Korrelation als r p 0.11 (p 0.28, n 100). Da hygienischen Bienenvo È lkern eine erho È hte Widerstandsfa Èhigkeit gegenu È ber Amerikanischer Faulbrut und der Kalkbrut zugesprochen wird, erscheint es lohnenswert das Hygieneverhalten durch Selektion zu fo È rdern, um so auch diesen potentiellen Varroatoleranz-Parameter bei den Honigbienen zu sta Èrken. U.S.

Summary — The proportion of damaged Varroa mites within the debris of honey bee colonies is discussed as a possible tolerance factor of the host. We investigated the rate of damaged Varroa females in honey bee colonies with and without hatching brood. Additionally, in some colonies sealed brood combs were treated by the use of heat or formic acid to kill the mites within the brood cells to quantify the behaviour of the bees towards dead mites. In 17 experimental honey bee colonies (Apis mellifera) at two different study sites, the debris was checked at 12-h intervals. Nearly 5 000 mites were individually analyzed for three different types of damages. The percentage of damaged mites varied on average from 44 to 63% depending on experimental conditions. No significant differences in the damage rates of 'phoretic mites' and 'brood mites' could be found. Dead mites from the treated brood combs were damaged to a slightly lesser extent. The significance of these results for the use of the parameter 'damaged mites' in selection programs is discussed.

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Summary — The response of A mellifera colonies to Varroa-infested brood cells has been investigated. Using special combs which guaranteed that the structure of the cell cap remained undamaged in the process of infestation, we infested worker brood cells with 1 or 2 mites each. The artificially infested cells were detected, uncapped and removed to various degrees by the worker bees of different carnica strains. Brood cells infested with 1 mite were removed from 5.5% (min) up to 95.8% (max) those with 2 Varroa from 4.8% (min) up to 100% (max) till 10 d after infestation. Figure 1 shows the means of the removed brood cells infested with one mite. The removal rates of the 2 infestation levels differed (P ≤ 0.01). Those colonies with a high removal response to brood cells infested with 1 mite also showed a high removal response to brood cells infested with two mites and vice versa (r = 0.76; P ≤ 0.001). Varroa mites escaped or were possibly killed. The signals which cause the removal are unknown. We do not know to what extent the method influences the magnitude of the removal behavior.