An ambiguous function of an alarm pheromone in the collective displays of the Australian meat ant, <i>Iridomyrmex purpureus</i>

Han, Shaolin; Chen, Wenman; Elgar, Mark A.

doi:10.1111/eth.13241

Cited by 7 publications

(6 citation statements)

References 50 publications

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“…Two chemically related compounds, 4-methyl-3-hexanol and 6-methyl-5-hepten-2-one, act as alarm pheromones in other ant species but were not found in clonal raider ant chemical extracts (Fig. 1A, Table S1; Bernardi et al, 1967;McGurk, 1968;Duffield et al, 1977;Pasteels et al, 1980;Pasteels et al, 1981;Morgan et al, 1992;Keegans et al, 1993;Oldham et al, 1994;Han et al, 2022;Lopes et al 2022).…”

Section: Alarm Pheromones Elicit a Range Of Behavioral Responsesmentioning

confidence: 99%

Sparse and stereotyped encoding implicates a core glomerulus for ant alarm behavior

Hart

Frank

Lopes

et al. 2022

Preprint

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Ants communicate via large arrays of pheromones and possess expanded, highly complex olfactory systems, with antennal lobes in the brain comprising ~500 glomeruli. This expansion implies that odors could activate hundreds of glomeruli, which would pose challenges for higher order processing. To study this problem, we generated the first transgenic ants, expressing the genetically encoded calcium indicator GCaMP6s in olfactory sensory neurons. Using two-photon imaging, we mapped complete glomerular responses to four ant alarm pheromones. Alarm pheromones robustly activated ≤6 glomeruli, and activity maps for the three pheromones inducing panic-alarm in our study species converged on a single glomerulus. These results demonstrate that, rather than using broadly tuned combinatorial encoding, ants employ precise, narrowly tuned, and stereotyped representation of alarm pheromone cues. The identification of a central sensory hub glomerulus for alarm behavior suggests that a simple neural architecture is sufficient to translate pheromone perception into behavioral outputs.

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Section: Alarm Pheromones Elicit a Range Of Behavioral Responsesmentioning

confidence: 99%

Sparse and stereotyped encoding implicates a core glomerulus for ant alarm behavior

Hart

Frank

Lopes

et al. 2022

Preprint

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“…Some alarm pheromones are multicomponent, and sometimes a single chemical compound is sufficient to induce a behavioral effect (Blum 1969). Components of the alarm pheromone are generally volatile, low molecular weight compounds, often terpenes, ketones, and aldehydes (Amoore et al 1969;Blum 1969;Brückner et al 2018;Pokorny et al 2020;Han et al 2022). Alarm behaviors, which are triggered by alarm pheromones, are robust, innate, and present across ant species.…”

Section: Introductionmentioning

confidence: 99%

The alarm pheromone and alarm response of the clonal raider ant

Lopes

Frank

Kárpáti

et al. 2022

Preprint

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Ants communicate via an arsenal of different pheromones produced in a variety of exocrine glands. For example, ants release alarm pheromones in response to danger to alert their nestmates and to trigger behavioral alarm responses. Here we characterize the alarm pheromone and the alarm response of the clonal raider antOoceraea biroi, a species that is amenable to laboratory studies but for which no pheromones have been identified. During an alarm response, ants quickly become unsettled, leave their nest pile, and are sometimes initially attracted to the source of alarm, but ultimately move away from it. We find that the alarm pheromone is released from the head of the ant and identify the putative alarm pheromone as a blend of two compounds found in the head, 4-methyl-3-heptanone and 4-methyl-3-heptanol. These compounds are sufficient to induce alarm behavior alone and in combination. They elicit similar, though slightly different behavioral features of the alarm response, with 4-methyl-3-heptanone being immediately repulsive and 4-methyl-3-heptanol being initially attractive before causing ants to move away. The behavioral response to these compounds in combination is dose-dependent, with ants becoming unsettled and attracted to the source of alarm pheromone at low concentrations and repulsed at high concentrations. While 4-methyl-3-heptanone and 4-methyl-3-heptanol are known alarm pheromones in other more distantly related ant species, this is the first report of the chemical identity of a pheromone inO. biroi, and the first alarm pheromone identified in the genusOoceraea. Identification of a pheromone that triggers a robust, consistent, and conserved behavior, like the alarm pheromone, provides an avenue to dissect the behavioral and neuronal mechanisms underpinning chemical communication.

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“…When worker ants form a larger and more compact colony, they still run erratically under the release of their alarm pheromone, however, most move deliberately towards alien objects and attack without hesitation, thus eliciting a “stand and hold defence”. This shift from panic to “aggressive alarm response” is often observed in Hymenopteran species as the colonies grow larger [ 23 , 54 ]. Alarm pheromones are thus either repellent when they trigger escape, or attractant when their function is to recruit more individuals to attack.…”

Section: Defensive Behaviour Based On Olfactory Communicationmentioning

confidence: 99%

Olfactory Strategies in the Defensive Behaviour of Insects

Kannan

Galizia

Nouvian

2022

Insects

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Most animals must defend themselves in order to survive. Defensive behaviour includes detecting predators or intruders, avoiding them by staying low-key or escaping or deterring them away by means of aggressive behaviour, i.e., attacking them. Responses vary across insect species, ranging from individual responses to coordinated group attacks in group-living species. Among different modalities of sensory perception, insects predominantly use the sense of smell to detect predators, intruders, and other threats. Furthermore, social insects, such as honeybees and ants, communicate about danger by means of alarm pheromones. In this review, we focus on how olfaction is put to use by insects in defensive behaviour. We review the knowledge of how chemical signals such as the alarm pheromone are processed in the insect brain. We further discuss future studies for understanding defensive behaviour and the role of olfaction.

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An ambiguous function of an alarm pheromone in the collective displays of the Australian meat ant, Iridomyrmex purpureus

Cited by 7 publications

References 50 publications

Sparse and stereotyped encoding implicates a core glomerulus for ant alarm behavior

Sparse and stereotyped encoding implicates a core glomerulus for ant alarm behavior

The alarm pheromone and alarm response of the clonal raider ant

Olfactory Strategies in the Defensive Behaviour of Insects

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