Straightforward Assay for Quantification of Social Avoidance in <em>Drosophila melanogaster</em>

Abstract

Drosophila melanogaster is an emerging model to study different aspects of social interactions. For example, flies avoid areas previously occupied by stressed conspecifics due to an odorant released during stress known as the Drosophila stress odorant (dSO). Through the use of the T-maze apparatus, one can quantify the avoidance of the dSO by responder flies in a very affordable and robust assay. Conditions necessary to obtain a strong performance are presented here. A stressful experience is necessary for the flies to emit dSO, as well as enough emitter flies to cause a robust avoidance response to the presence of dSO. Genetic background, but not their group size, strongly altered the avoidance of the dSO by the responder flies. Canton-S and Elwood display a higher performance in avoiding the dSO than Oregon and Samarkand strains. This behavioral assay will allow identification of mechanisms underlying this social behavior, and the assessment of the influence of genes and environmental conditions on both emission and avoidance of the dSO. Such an assay can be included in batteries of simple diagnostic tests used to identify social deficiencies of mutants or environmental conditions of interest.

Drosophilamutants of the autism candidategene neurobeachin(rugose) exhibit neuro-developmental disorders, aberrant synaptic properties, altered locomotion, and impaired adult social behavior and activity patterns

“…CS flies strongly avoid the dSO left by agitated flies (Figure 7A) as shown previously (Suh et al, 2004; Fernandez et al 2014). In contrast, both rg p2 and rg p6 mutants displayed a decreased performance compared to CS.…”

“…Our conclusion is based on outcomes of rg mutants’ behavior in assays of social signals. We first tested the ability of the flies to avoid the Drosophila stress odorant (dSO) left by agitated flies in the avoidance assay (Suh et al, 2004; Fernandez et al, 2014). We also tested the flies’ response to others in social clustering, the measure of distances to their closest neighbor (their social space), in a stable undisturbed group (Burg et al, 2013; Simon et al, 2012).…”

“…Assays for the avoidance of social stress odorant were conducted using a T-maze with an n=40 tester male fly group, and around 70 mixed gender CS emitters flies, as described in Suh et al (2004) and Fernandez et al (2014). Emitter flies were agitated on a vortex mixer in 15 sec.…”

“…Pictures were taken once the flies reached a stable clustering, in which limited or no motion is seen, as described (Simon et al, 2012; Fernandez et al, 2014). Because the mutant flies were hyperactive, such stable clustering was not reached until 40 minutes after flies were placed in chambers.…”

IsDrosophila melanogasterStress Odorant (dSO) really an alarm pheromone?

“…However, the avoidance response is weaker to CO 2 alone than to dSO suggesting other components are present (Suh et al, 2004). We know that both sexes respond to dSO, although the levels of response vary as a function of the genetic background (Fernandez et al, 2014) and age (Brenman-Suttner et al, 2018), as well as the density of emitters (Fernandez et al, 2014). In order to facilitate the identification of the complete blend of dSO, as well as the genes and sensory pathways involved, it is essential to know the conditions that result in high production of the olfactory cue.…”