Selective Behaviour of Honeybees in Acquiring Euro

Authors: Valery A Isidorov Sławomir Bakier Ewa Pirożnikow Monika Zambrzycka Izabela Swiecicka

Publish Date: 2016/06/13

Volume: 42, Issue: 6, Pages: 475-485

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Abstract

Honey bees harvest resins from various plant species and use them in the hive as propolis While there have been a number of studies concerning the chemical composition of this antimicrobial product little is known about selective behavior and bee preference when different potential plant sources of resin are available The main objective of this paper was to investigate some aspects of behavioral patterns of honeybees in the context of resin acquisition Samples of propolis originating from temperate zones of Europe and the supposed botanical precursors of the product were analyzed Taxonomical markers of bud resins of two white birch species aspen black poplar horsechestnut black alder and Scots pine were determined through GCMS analysis All these trees have been reported as sources of propolis but comparisons of the chemical composition of their bud resins with the compositions of propolis samples from seven European countries have demonstrated the presence of taxonomical markers only from black poplar aspen and one species of birch This suggests selective behavior during the collection of bud resins by honeybees To examine the causes of such selectivity the antimicrobial properties of bud resins were determined Horsechestnut resins had lower antimicrobial activity than the other resins which did not differ significantlyPropolis is a mixture of wax and resin exudate collected by honeybees from buds of various trees Bankova et al 2000 Bud resins with addition of bee salivary enzymes Kaczmarek and Dębowski 1983 and beeswax have been used in the hive not only as a building material to seal hive walls and strengthen comb cells but also as an antimicrobial agent against a variety of pathogens SimoneFinstrom and Spivak 2010 Apart from Varroa destructor mites and viruses other pathogens include bacteria fungi and protozoa Evans and Schwarz 2011 Shimanuki and Knox 2000 These pathogens are common in the honeybees’ natural environment and are brought into the hive by worker bees together with nectar pollen and water Chechetkina et al 2010 Owing to its antimicrobial properties propolis can reduce disease at the colony level SimoneFinstrom and Spivak 2010 and provide social immunity to the bee family Evans and Spivak 2010 Thus resin acquisition is a social process that is controlled by the bee colony as a whole Nakamura and Seeley 2006Propolis antimicrobial activity has been attributed to flavonoid aglycones and phenolic and hydroxycinnamic acids The content in bud resins of different plant species varies widely Bankova et al 2006 It is believed that the main precursors of European and North American propolis are resins from buds of different poplar species Bankova et al 2000 Greenaway and Whatley 1990 Greenaway et al 1988 1990 Popravko 1978 Wilson et al 2013 Other plant resins reported as precursors of propolis in the temperate zone of the Northern Hemisphere include resins of aspen and silver birch Popravko et al 1983 1985 as well as pine alder horsechestnut elm ash oak and beech Crane 1990 Ghisalberti 1979 Greenaway et al 1988 König 1985 Markham et al 1996 SimoneFinstrom and Spivak 2010 Mixed types of propolis containing exudates of more than one plant species have been reported Bankova et al 2002 Isidorov et al 2014a Popova et al 2005 2013 This prompts the question as to whether honeybees show selectivity when collecting propolis precursors from available plant sourcesBornean stingless bees have been shown to make choices by collecting resin from some plants rather than others Leonhardt and Blüthgen 2009 and Wilson et al 2013 2015 found that honeybees from their apiary discriminately foraged for resin from two American poplar species Populus deltoides and P balsamifera and did not collect other resins from even closely related plants Availability proximity and perhaps toxicity played a role in the selection of resins Wilson et al 2013 However the authors did not analyze the chemical composition of resins and propolis and little is known about the botanical precursors of propolis in other regions such as the boreal zone of EurasiaThe aims of this paper were to determine the chemical composition of resin from plants assumed to be sources for propolis in Europe and to explore their benefits to bees The chemical compositions of bud resins from seven potential plant precursors were compared with the compositions of propolis from different climatic zones of Europe and the antimicrobial properties of the materials were measured To our knowledge the antimicrobial activities of bud resins from trees typically found in Europe have not been analyzed previously with the exception of Scots pine and horsechestnut Wilson et al 2013Pyridine bistrimethylsilyltrifluoroacetamide BSTFA containing 1  trimethylchlorosilane and dimethyl sulfoxide DMSO were purchased from SigmaAldrich Poznan Poland Extractions were carried out with diethyl ether POCH SA Gliwice PolandAll samples of propolis were collected in late summer in the second half of July and August of 2014 Three propolis samples Pr1 Pr2 and Pr6 originated from the same apiary located in North Eastern Latvia 57o 85′ N 26o 27′ E two samples Pr4 and Pr5 were collected by Russian apiarists respectively in the Vologda region Pr4 59o 58′ N 38o 31′ E and the Udmurt Republic 58o 14′ N 52o 07′ E Single samples were supplied from Finland Pr3 61o 43′ N 25o 26′ E North Eastern Poland Bialystok region Pr7 53o 14′ N 23o 42′ E Ukraine Poltava region Pr8 48o 43′ N 33o 29′ Slovakia Pr9 48o 16′ N 17o 30′ E and France RhôneAlpes Region Pr10 45o 07′ N 5o 20′ E Propolis samples Pr1 Pr2 Pr6 and Pr7 were collected by the authors in August 2014 To acquire the material a terylene net mesh size of 1 mm was mounted just above the hive frames with the brood After 3 wk the net became glued with pure propolis by the bees and this was easily removed after cooling to −18 °C The remaining samples 10–15 g of each were gathered in the summers of 2013 and 2014 by apiarists from the different countries

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