Giant Asian honeybees use olfactory eavesdropping to detect and avoid ant predators

Abstract

Keywords: eavesdropping giant Asian honeybee pollinator predatoreprey interaction trail pheromone weaver ant Pollinators provide a key ecosystem service that can be influenced by predation and predator avoidance. However, it was unclear whether pollinators can avoid predators by eavesdropping, intercepting predator signals. Using a natural species assemblage, we show that a bee can eavesdrop on and avoid the trail pheromone of a sympatric ant, while foraging on a native plant. The giant Asian honeybee, Apis dorsata, avoided Calliandra haematocephala inflorescences with live weaver ants, Oecophylla smaragdina. Although few foraging bees were attacked, ants killed the bee in almost a third of attacks. Ant presence alone significantly reduced bee floral visits. Bees showed nearly equal avoidance of live ants and trail pheromone extracts, demonstrating that olfactory eavesdropping alone can elicit full avoidance. We then used GC-MS to analyse compounds deposited by ants walking and laying trail pheromone. The most abundant compounds were all trail pheromone components. However, bees did not avoid the most abundant and conspicuous trail pheromone compound, heneicosane. Foragers may instead detect a mixture of different trail pheromone compounds. Our results contribute to a growing understanding of how public information about predators and competitors can shape food webs, and show that pollinators can tap into the private signals of predators and use this information to their advantage.

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

“…We also observed weaver ants (Oecophylla smaragdina) attacking A. dorsata foraging on inflorescences (Calliandra haematocephala). Ants attacked 3% of visiting bees (980 bee visits observed) and 31% of these attacks successfully killed the bee forager (Li et al, 2014). Ant presence alone significantly reduced bee floral visitation by 40% (Li et al, 2014).…”

“…Ants attacked 3% of visiting bees (980 bee visits observed) and 31% of these attacks successfully killed the bee forager (Li et al, 2014). Ant presence alone significantly reduced bee floral visitation by 40% (Li et al, 2014). During these attacks, we smelled A. dorsata alarm phermone released by attacked bees, and we wished to determine whether this alarm pheromone would repel foragers.…”

Oecophylla smaragdinaants provide pest control in Australian cacao

“…, Goodlae & Nieh ), including O. smaragdina recruitment odor trails that may aid predator detection and avoidance by plant‐visiting herbivorous insects (Li et al . ). For example, Offenberg et al .…”

“…However, O. smaragdina ants also produce a conspicuous, long-lasting recruitment odor trail that remains strong for at least 24 h and persists for 3 d (Jander & Jander 1979). Insects can identify olfactory cues associated with predation (Abbott 2006, Goncalves-Souza et al 2008, Goodlae & Nieh 2012, including O. smaragdina recruitment odor trails that may aid predator detection and avoidance by plant-visiting herbivorous insects (Li et al 2014). For example, Offenberg et al (2004) report that R. wallacei beetles can detect and actively avoid O. smaragdina pheromone.…”

Does signal deterioration compromise eavesdropping on other species' alarm calls?

“…Pupin, Sacchi, Gentilli, Galeotti, & Fasola, 2007), many predators or parasites locate prey by eavesdropping on their mating signals (review: Zuk & Kolluru, 1998), and prey may avoid predators by eavesdropping on their signals (e.g. Li, Wang, Tan, Qu, & Nieh, 2014). The information gained by eavesdroppers is not necessarily similar to the information gained by intended receivers; a mating signal, for example, reveals the location of food to an eavesdropping predator but helps find a mate for the intended receiver.…”