Attraction to and learning from social cues in fruitfly larvae

Abstract

We examined the use of social information in fruitfly larvae, which represent an ideal model system owing to their robust learning abilities, small number of neurons and well-studied neurogenetics. Focal larvae showed attraction to the distinct odour emanating from food occupied by other larvae. In controlled learning experiments, focal larvae preferred novel odours previously paired with food occupied by other larvae over novel odours previously paired with unoccupied food. When we gave groups of larvae a choice between food patches differing in quality, more larvae aggregated on the higher-quality food, suggesting that attraction to and learning about cues associated with other larvae can be beneficial. Furthermore, larvae were more likely to find the best available food patch in trials when that food patch was occupied by other larvae than in trials when that food patch was unoccupied. Our data suggest, however, that the benefits from joining others may be at least partially offset by the fitness costs of increased competition, because larvae reared in isolation did as well as or better than larvae reared in groups on three key fitness parameters: developmental rate, survival rate and adult dry body mass. Our work establishes fruitfly larvae as a highly tractable model species for further research on the mechanisms that modulate behaviour and learning in a social context.

Social attraction mediated by fruit flies' microbiome

“…Furthermore, larvae and adults learn to prefer odours from food substrates that have been occupied by larvae over odours from unoccupied substrates of similar quality (Durisko and Dukas, 2013;Durisko et al, 2014). Our controlled experiments indicated that the social attraction we documented was not caused by odours from either fruit or yeast.…”

“…larvae in tests with wild-caught larval and adult fruit flies as well as in experiments using natural fruit (Durisko and Dukas, 2013;Durisko et al, 2014). Volatiles from both L. brevis, which we cultured from our fly population, and L. plantarum, which has been isolated from the Drosophila gut in other studies, were attractive.…”

“…The standard condition was identical to that of Durisko and Dukas (Durisko and Dukas, 2013), and consisted of testing each focal for attraction to standard used food that has been occupied and consumed by 30 standard larvae for 24 h versus standard fresh food aged for 24 h. The axenic condition involved testing each focal for attraction to axenic used food that has been occupied and consumed by 30 axenic larvae for 24 h versus axenic fresh food aged for 24 h. We placed the 2.5 ml food discs 1 cm apart, equidistant to the midline, alternating sides between trials. We tested focals individually, placing one at a time facing away from the experimenter, parallel to the midline of a fresh 100 mm agar Petri dish, through a 1 cm opening in the lid.…”

“…We followed a standard associative learning protocol (Durisko and Dukas, 2013) and tested axenic mid-third-instar larvae (n=96). The main treatment involved standard used food occupied and consumed by 30 standard larvae for 24 h and axenic used food occupied and consumed by 30 axenic larvae for 24 h. The control treatment was identical to the one used by Durisko and Dukas (Durisko and Dukas, 2013) and included standard used food occupied and consumed by 30 standard larvae for 24 h and standard fresh food.…”

Studying host-microbiota mutualism in Drosophila: Harnessing the power of gnotobiotic flies

“…In the wild, fruit flies search of hospitable habitat with suitable food substrate for mating, egg laying, and rearing larvae. [56] The results from this study imply that the host interaction with the commensal Lactobacillus genus of the gut microbiota can manufacture compounds that serve as cues for the host's searching effort and decision-making. What are these compounds?…”