This study examined the impact of suboptimal food sources on larval L. sericata, constructing an imbalanced diet with and without antimicrobial treatment, using the essential amino acids phenylalanine, methionine, valine, and tryptophan, the corresponding volatile organic compounds (VOCs) of which are known fly attractants.
As primary colonizers of ephemeral resources, the common green bottle fly, Lucilia sericata, must exercise efficient resource exploitation strategies to maximize fitness. Foraging incurs costs, so the efficient evaluation of resources is essential for individuals relying on fragmented patches whose dissimilarity may result in fitness consequences for offspring. Thus, selective pressures between carrion-using insects and carrion-associated microbes are expected to occur. Microbes play a pivotal role in adult fly assessment of resources via production of volatile organic compounds (VOCs) resulting from the breakdown of essential amino acids. If one assumes that chemoreception of these VOCs provides public information regarding the corresponding essential amino acids, the resulting effects on maternal decision-making could impact larval resource exploitation. The current study's findings demonstrate that both amino acid composition and microbial presence influence behavior, with larvae displaying a preference for untreated diets lacking methionine and a complete reversal in preference for antimicrobial-treated diets. This interaction between diet and antimicrobial treatment indicates that the presence of microbes that produce essential amino acids may impact larval resource use strategies. This investigation into larval performance on diets deficient in amino acids that provide important VOC cues to maternal flies provides a stepping-stone for dissecting larval behavioral strategies on ephemeral resources when faced with limited choices. (publisher abstract modified)