In their natural habitat foraging bumblebees refuse to land on and probe flowers that have been recently visited (and depleted) by themselves, conspecifics or other bees, which increases their overall rate of nectar intake. This avoidance is often based on recognition of scent marks deposited by previous visitors. While the term ‘scent mark’ implies active labelling, it is an open question whether the repellent chemicals are pheromones actively and specifically released during flower visits, or mere footprints deposited unspecifically wherever bees walk. To distinguish between the two possibilities, we presented worker bumblebees (Bombus terrestris) with three types of feeders in a laboratory experiment: unvisited control feeders, passive feeders with a corolla that the bee had walked over on its way from the nest (with unspecific footprints), and active feeders, which the bee had just visited and depleted, but which were immediately refilled with sugar–water (potentially with specific scent marks). Bumblebees rejected both active and passive feeders more frequently than unvisited controls. The rate of rejection of passive feeders was only slightly lower than that of active feeders, and this difference vanished completely when passive corollas were walked over repeatedly on the way from the nest. Thus, mere footprints were sufficient to emulate the repellent effect of an actual feeder visit. In confirmation, glass slides on which bumblebees had walked on near the nest entrance accumulated hydrocarbons (alkanes and alkenes, C23 to C31), which had previously been shown to elicit repellency in flower choice experiments. We conclude that repellent scent marks are mere footprints, which foraging bees avoid when they encounter them in a foraging context.
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We thank Sebastian Witjes for advice and help with the experiments. Klaus Lunau and the members of Sensory Ecology Seminar provided critical comments that improved the manuscript. The experiments comply with the current laws of Germany. This study is supported by DFG grant EL 249/4.
Federle W, Riehle M, Curtis ASG, Full RJ (2002) An integrative study of insect adhesion: mechanics and wet adhesion of pretarsal pads in ants. Integr Comp Biol 42:1100–1106CrossRefGoogle Scholar
Gawleta N, Zimmermann Y, Eltz T (2005) Repellent foraging scent recognition across bee families. Apidologie 36:325–330CrossRefGoogle Scholar
Goulson D, Hawson SA, Stout JC (1998) Foraging bumblebees avoid flowers already visited by conspecifics or by other bumblebee species. Anim Behav 55:199–206PubMedCrossRefGoogle Scholar
Goulson D, Stout JC, Langley J, Hughes WOH (2000) Identity and function of scent marks deposited by foraging bumblebees. J Chem Ecol 26:2897–2911CrossRefGoogle Scholar
Jandt JM, Curry C, Hemauer S, Jeanne RL (2005) The accumulation of a chemical cue: nest-entrance trail in the German yellowjacket, Vespula germanica. Naturwissenschaften 92:242–245PubMedCrossRefGoogle Scholar
Jarau S, Hrncir M, Zucchi R, Barth FG (2005) Morphology and structure of the tarsal glands of the stingless bee Melipona seminigra. Naturwissenschaften 92:147–150PubMedCrossRefGoogle Scholar
Jiao Y, Gorb S, Scherge M (2000) Adhesion measured on the attachment pads of Tettigonia viridissima (Orthoptera, Insecta). J Exp Biol 203:1887–1895PubMedGoogle Scholar
Kosaki A, Yamaoka R (1996) Chemical composition of footprints and cuticular lipids of three species of lady beetles. Jpn J Appl Entomol Zool 40:47–53Google Scholar
Lockey KH (1988) Lipids of the insect cuticle: origin, composition and function. Comp Biochem Physiol B 89:595–645CrossRefGoogle Scholar
Oldham NJ, Billen J, Morgan ED (1994) On the similarity of the Dufour gland secretion and the cuticular hydrocarbons of some bumblebees. Physiol Entomol 19:115–123Google Scholar
Saleh N, Chittka L (2006) The importance of experience in the interpretation of conspecific chemical signals. Behav Ecol Sociobiol 61:215–220CrossRefGoogle Scholar
Schmidt VM, Zucchi R, Barth FG (2005) Scent marks left by Nannotrigona testaceicornis at the feeding site: cues rather than signals. Apidologie 36:285–291CrossRefGoogle Scholar
Schmitt U, Bertsch A (1990) Do foraging bumblebees scent-mark food sources and does it matter? Oecologia 82:137–144CrossRefGoogle Scholar
Schmitt U, Lübke G, Francke W (1991) Tarsal secretion marks food sources in bumblebees (Hymenoptera: Apidae). Chemoecology 2:35–40CrossRefGoogle Scholar
Stout JC, Goulson D (2002) The influence of nectar secretion rates on the responses of bumblebees (Bombus spp.) to previously visited flowers. Behav Ecol Sociobiol 52:239–246CrossRefGoogle Scholar
Stout JC, Goulson D, Allen JA (1998) Repellent scent-marking of flowers by a guild of foraging bumblebees (Bombus spp.). Behav Ecol Sociobiol 43:317–326CrossRefGoogle Scholar
Thomson JD, Chittka L (2001) Pollinator individuallity: when does it matter? In: Chittka L, Thomson JD (eds) Cognitive Ecology of Pollination. Cambridge University Press, pp 191–213Google Scholar
Votsch W, Nicholson G, Muller R, Stierhof YD, Gorb S, Schwarz U (2002) Chemical composition of the attachment pad secretion of the locust Locusta migratoria. Insect Biochem Mol Biol 32:1605–1613PubMedCrossRefGoogle Scholar
Witjes S, Eltz T (2007) Influence of scent deposits on flower choice: experiments in an artificial flower array with bumblebees. Apidologie 38:12–18CrossRefGoogle Scholar