RESUMEN
BACKGROUND: The influence of microbiota in ecological interactions, and in particular competition, is poorly known. We studied competition between two insect species, the invasive pest Drosophila suzukii and the model Drosophila melanogaster, whose larval ecological niches overlap in ripe, but not rotten, fruit. RESULTS: We discovered D. suzukii females prevent costly interspecific larval competition by avoiding oviposition on substrates previously visited by D. melanogaster. More precisely, D. melanogaster association with gut bacteria of the genus Lactobacillus triggered D. suzukii avoidance. However, D. suzukii avoidance behavior is condition-dependent, and D. suzukii females that themselves carry D. melanogaster bacteria stop avoiding sites visited by D. melanogaster. The adaptive significance of avoiding cues from the competitor's microbiota was revealed by experimentally reproducing in-fruit larval competition: reduced survival of D. suzukii larvae only occurred if the competitor had its normal microbiota. CONCLUSIONS: This study establishes microbiotas as potent mediators of interspecific competition and reveals a central role for context-dependent behaviors under bacterial influence. Video Abstract.
Asunto(s)
Drosophila , Microbiota , Femenino , Animales , Drosophila melanogaster , Frutas , Lactobacillus , LarvaRESUMEN
Interactions between microorganisms associated with metazoan hosts are emerging as key features of symbiotic systems. Little is known about the role of such interactions on the maintenance of host-microorganism association throughout the host's life cycle. We studied the influence of extracellular bacteria on the maintenance of a wild isolate of the yeast Saccharomyces cerevisiae through metamorphosis of the fly Drosophila melanogaster reared in fruit. Yeasts maintained through metamorphosis only when larvae were associated with extracellular bacteria isolated from D. melanogaster faeces. One of these isolates, an Enterobacteriaceae, favoured yeast maintenance during metamorphosis. Such bacterial influence on host-yeast association may have consequences for the ecology and evolution of insect-yeast-bacteria symbioses in the wild.