Natural history of model organisms: The secret (group) life of Drosophila melanogaster larvae and why it matters to developmental ecology

Abstract

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The transcriptomic signature of physiological trade-offs caused by larval overcrowding in Drosophila melanogaster

“…This finding challenges the prediction that Drosophila larvae should upregulate immune function due to density-dependent prophylaxis as in other insects (e.g., [37,66]). However, it is possible that the larval densities used here, which are above those found in nature (see [34]), are above the larval densities which stimulates immunity. Nevertheless, the repression of transcripts involved in immunity found here is likely responsible for increased larval mortality in crowded conditions found here and elsewhere [27], which imposes a strong selective pressure for populations experiencing high larval densities.…”

“…Drosophila melanogaster is the ideal model system to investigate the molecular responses to overcrowding for several reasons. First, Drosophila larvae are thought to be relatively immobile and, therefore, strongly influenced by interspecific competition [13,34]. Second, larval density modulates a range of fitness-related traits in both positive (e.g., hormesis-like) and negative (e.g., lower mating success) manners [18,19,22,29].…”

Assessing anatomical changes in male reproductive organs in response to larval crowding using micro-computed tomography imaging

“…In this study, we used 3D micro-CT imaging to analyse the volume of D. melanogaster male’ reproductive organs over a range of larval densities. Larval density range was chosen based on our previous ecological assessment of D. melanogaster larvae in a natural population (Morimoto and Pietras, 2020) and included densities ranging from low, natural range, and high larval densities relative to the densities observed in nature. This approach allowed us to apply our 3D micro-CT technique to an ecologically relevant experimental design for the species.…”

Larval densities of the protected Striped lychnis moth Shargacucullia lychnis (Lepidoptera: Noctuidae) in Buckinghamshire

“…This is because in holometabolous insects, larval density modulates life histories and fitness [reviewed by (Than et al, 2020)], including responses to temperature that can be crucial for adaptation to climate change (Henry, Renault, & Colinet, 2018;Lushchak et al, 2019). In fact, only recently have we had a direct glimpse of the natural population densities experienced by Drosophila melanogaster larvae, a species that is arguably the most well-studied insect in the world (Markow, 2015;Morimoto & Pietras, 2020). This study revealed that the majority of laboratory methodologies might have failed to manipulate larval density in values that were ecologically relevant to understand responses to both low and high densities (Morimoto & Pietras, 2020).…”

“…In fact, only recently have we had a direct glimpse of the natural population densities experienced by Drosophila melanogaster larvae, a species that is arguably the most well-studied insect in the world (Markow, 2015;Morimoto & Pietras, 2020). This study revealed that the majority of laboratory methodologies might have failed to manipulate larval density in values that were ecologically relevant to understand responses to both low and high densities (Morimoto & Pietras, 2020). It is, therefore, not surprising that for other insects, little or no information on the natural history of larval density is available in the published literature.…”