Comparison af powdered sugar and detergent methods to determine Varroa infestation level in honey bee colonies

Bu çalışma; bal arısı kolonilerinde Varroa bulaşıklık oranını belirlemede pudra şekeri ve deterjan yöntemlerinin karşılaştırılması amacı ile yapılmıştır. Çalışmada toplam 1 koloniden ortalama 304.72±16.56 adet işçi arı numunesi silkeleme yöntemi ile alınarak pudra şekeri ilavesi ile plastik kutularda 5 dakika çalkalanmış ve arılar üzerinden düşen varroa sayıları tespit edilmiştir. Yöntemin etkinliğini tespit için Varroa sayıları belirlenen örnek arılar deterjanlı su içerisinde 5 dakika çalkalanarak kalan varroa sayıları tespit edilmiştir. Sonuç olarak pudra şekeri kullanımı ile ergin arılar üzerinde bulunan varroaların % 94’ünün tespit edilebildiği belirlenmiştir. Pudra şekeri yöntemi ile işçi arıların öldürülmeden kolonilere geri verilmesi, özellikle erken ilkbahar ve geç sonbahar bulaşıklık seviyelerinin belirlenmesinde arıcılar ve araştırmacılar tarafından uygulamada tercih edilebileceğini düşündürmektedir. Yöntemin Varroa bulaşıklık oranlarının belirlenmesinde, saha ilaç denemelerinde ve ıslah çalışmalarında yararlı olacağı önerilmektedir.The determination of Varroa mite infestation levels in honey bee colonies is a standard requirement to assess the colony endangerment or the effect of treatments. Analysing bee sampes has been shown to be more reliable than brood samples, and washing of approximately 30g bees in detergent water is and established method of high reliability (Fuchs 1985). Here we investigate the reliability of shaking bee samples with powder sugar, where bees are not killed in the process and which can easily performed at the beeyard. Materials and Methods About 30 g bees (average 305 bees, N=11) were shaken from a brood comb from the middle of the colony through a wide funnel into a 500 ml plastic jar containing about 100 g dry powder sugar taken from standard 250 g commercial packages, and were gently shaken by hand over 5 min. Then the bees were separated from the powder sugar with the mites using separate jar with a 2x3 mm gauze sieve attached to the bottom. Next, the mites were separated from the sugar with a common household sieve (0.5x0.5 mm mesh width). To evaluate the efficacy, bee samples were then additionally washed with detergent water in jars with a sieve bottom insert. In 2 cases, bees were inspected individually for remaining mites. However, in a normal procedure these bees would have returned to their colonies alive. In a further set, 10 colonies were tested with used powder sugar. Results The results of the shaking procedure are shown in Table 1. In total of the 10 bee samples, 174 mites were found on 3352 bees (average 15.8±7.2 and 304.7±55.0, respectively). Of these 163 mites were found by powder sugar shaking (average 14.8±7.1), which resuts in an total efficay of 94% (average 94±9 %). After detergent water washing, no mites were found in 3 samples inspected manually. Using pre-used powder sugar collected in a bucket and stored over 4 month gave a considerable lower powder sugar recovery rate. Here, in a total of 196 Varroa mites in the 10 bee samples containing 4584 bees only 46 (23%) were recovered by powder sugar shaking (Averages: 458.5±95.3, 19,6±9.7, 4.6±2.3 and 31±2%, repectively). Conclusion According to this results powder sugar shaking can be regarded to be a sufficiently reliable method to determine the degree honey bee worker infestation with Varroa mites for any practical purpose. If compared with standard detergent water shaking known to be reliable (Fuchs 1985), more than 90% of the mites were recovered in 7 out of 11 samples (average 94%). However, our results also show that the efficacy drastically reduced by humidity in the powder sugar. Thus it is recommended that only sealed-packaged fresh powder sugar is used. Also, as bees may regurgitate some stomach content during shaking, it also underlines the necessity to use a fair amount of sugar in relation to the bee samople size to absorb some moisture still without getting sticky. Considering the advantages that sample analysis can be performed directly at the bee yard within approximately 10 min per hive with immediate results and saving the labelling, storing, transporting and laboratory shaking of the samples powder sugar shaking is preferable to washing from a practical viewpoint. Moreover, that bees do survive the procedure without apparent damages does allow to sample even on small colonies without depleting it of bees, which makes the method considerably more acceptable to beekeepers.Bu çalışma TAGEM (Proje No. 09/A-GE/10) ve AB (Proje No. 2808UM003) tarafından desteklenmiştir