Effects of natural and synthetic alarm pheromone and individual pheromone components on foraging behavior of the giant Asian honey bee,Apis dorsata

Abstract

Social pollinators such as honey bees face attacks from predators not only at the nest, but also during foraging. Pollinating honey bees can therefore release alarm pheromones that deter conspecifics from visiting dangerous inflorescences. However, the effect of alarm pheromone and its chemical components upon bee avoidance of dangerous food sources remains unclear. We tested the responses of giant honey bee foragers, Apis dorsata, presented with alarm pheromone at a floral array. Foragers investigated the inflorescence with natural alarm pheromone, but 3.3-fold more foragers preferred to land on the 'safe' inflorescence without alarm pheromone. Using gas chromatography-mass spectrometry analysis, we identified eight chemical components in the alarm pheromone, of which three components (1-octanol, decanal and gamma-octanoic lactone) have not previously been reported in this species. We bioassayed six major compounds and found that a synthetic mixture of these compounds elicited behaviors statistically indistinguishable from responses to natural alarm pheromone. By testing each compound separately, we show that gamma-octanoic lactone, isopentyl acetate and (E)-2-decen-1-yl acetate are active compounds that elicit significant alarm responses. Gamma-octanoic lactone elicited the strongest response to a single compound and has not been previously reported in honey bee alarm pheromone. Isopentyl acetate is widely found in the alarm pheromones of sympatric Asian honey bee species, and thus alarmed A. dorsata foragers may produce information useful for conspecifics and heterospecifics, thereby broadening the effects of alarm information on plant pollination.

Olfactory eavesdropping of predator alarm pheromone by sympatric but not allopatric prey

“…Honey bees generally respond more strongly to the complete cocktail of honey bee sting alarm pheromone components than to a single component: Ac , Am (Nouvian, Reinhard, & Giurfa, 2016) and A. dorsata (Li, Wang, Tan, Qu, & Nieh, 2014a). In our study, BA, DA and OA did not elicit strong responses when individually presented at one bee-equivalent.…”

“…In multiple wasp species, sting venom volatiles are the main source of alarm pheromone: Polistes dominulus (Bruschini, Dani, Pieraccini, & Guarna, 2006), Dolichovespula maculata (Jimenez et al, 2016), Vespula squamosa (Heath & Landolt, 1988;Landolt, Heath, Reed, & Manning, 1995), Vespa crabro (Veith, Koeniger, & Maschwitz, 1984), Vespa mandarinia (Ono, Terabe, Hori, & Sasaki, 2003), Vespa simillima xanthoptera (Ono et al, 2003) and V. velutina . All honey bee species studied, to date, also use their sting venom volatile as an alarm pheromone (Li et al, 2014a). To avoid Ac eavesdropping, it seems that hornets could eliminate their production of alarm pheromone during Ac nest attacks.…”

Poison and alarm: The Asian hornetVespa velutinauses sting venom volatiles as alarm pheromone

“…Alarm pheromones can play dual roles, by activating nest defence and serving as a warning that allows foragers to avoid dangerous sites. For example, honeybee alarm pheromone can attract guards to the nest entrance for nest defence (Boch and Shearer, 1971;Roubik, 1989) and repel foragers from foraging sites with predators (Li et al, 2014;Wang et al, 2016). In social wasps and hornets, nest guards can also release alarm pheromones to recruit nest defenders (Bruschini et al, 2008).…”

The use of the lactone motif in chemical communication

“…The only other known b-lactones used as semiochemicals are viridiorine-b-lactone (25) and norviridiorine-b-lactone (26), originally identied in the tropical buttery Idea leuconoe (Danainae). [14][15][16] The major b-lactone 25 is a component of the male sex pheromone of this buttery, attracting females over short distances.…”

“…25 4-Octanolide of unknown stereochemistry (32) is the major constituent of the alarm pheromone of the giant honey bee, Apis dorsata. 26 Additional compounds such as isopentyl acetate and (E)-2-decenyl acetate enhanced the pheromonal activity.…”