Turning food into eggs: insights from nutritional biology and developmental physiology of Drosophila

Terminal investment strategies following infection are dependent on diet

“…Given the key role of protein, particularly in females and invertebrates (Fanson, Fanson, & Taylor, ; Mirth et al, ; Moatt et al, ; Piper, Partridge, Raubenheimer, & Simpson, ), we interpret our results in relation to protein content of the diet. In Drosophila , both the quantity of protein per egg and the quantity of eggs produced are influenced by dietary protein availability (Mirth et al, ). Female D. melanogaster typically weigh 800–1100 μg (Jumbo‐Lucioni et al, ) and lay eggs containing approximately 10–12 μg of protein each (Kutzer & Armitage, ).…”

“…We found that oral infection by P. aeruginosa was sufficient to trigger a shift in reproductive investment, recapitulating similar increases in reproductive output in D. melanogaster following sub‐lethal viral infections (Gupta, Stewart, et al, ). Given the elevated protein requirements of oogenesis (Mirth et al, ), we hypothesized that terminal investment would be more likely to be observed when protein was not limited. We observed increased reproductive investment in both diet treatments, although the nature of these terminal investment strategies depended on the availability of dietary protein.…”

“…The precise mechanisms by which changes in diet affect reproductive traits following infection are difficult to disentangle. Dietary protein provides both the raw material for egg production and also influences complex signalling pathways which determine investment in egg production (Mirth et al, ). Our results showed that flies on the standard diet could produce eggs with higher viability but did not invest in doing so in the absence of infection.…”

“…Fruit flies ( Drosophila melanogaster ) produce more eggs on protein‐rich diets, and these eggs are more likely to be viable (Drummond‐Barbosa & Spradling, ; Lee et al, ; Lihoreau, Poissonnier, Isabel, & Dussutour, ; Mirth et al, ). Egg protein content is influenced directly by dietary protein (Kutzer & Armitage, ; Mirth et al, ) and has been shown to correlate with hatchling size (Stahlschmidt, Rollinson, Acker, & Adamo, ). Egg protein content may additionally be subject to trade‐offs against the immune response, evidenced by immune challenged female mosquitoes ( Anopheles gambiae ) laying eggs with lower protein content (Ahmed, Baggott, Maingon, & Hurd, ).…”

“…Terminal investment reallocates resources from other somatic functions to current reproductive effort and should therefore rely heavily on the acquisition of dietary nutrients, their transformation into energy resources and the appropriate allocation of these resources to different life-history traits (Schwenke et al, 2016). Diet is known to affect both fecundity and immunity across a wide range of species (Jensen, McClure, Priest, & Hunt, 2015;Lee, Simpson, & Wilson, 2008;Maklakov et al, 2008;Rapkin et al, 2018;Schwenke et al, 2016), and protein in particular is a key resource for growth, development and reproduction (Mirth, Nogueira Alves, & Piper, 2019). Fruit flies (Drosophila melanogaster) produce more eggs on protein-rich diets, and these eggs are more likely to be viable (Drummond-Barbosa & Spradling, 2001;Lee et al, 2008;Lihoreau, Poissonnier, Isabel, & Dussutour, 2016;Mirth et al, 2019).…”