Circulating triacylglycerides influence egg-to-adult viability in Drosophila melanogaster

Triacylglycerides (TAGs) are neutral lipids and are one of the major energy storage forms in an insect aiding in normal physiology including reproduction of the organism. Importance of TAG metabolism in gametogenesis has been investigated in insects like mosquitoes, silkworm and Drosophila. However, a direct association between TAG levels and egg-to-adult viability has not been explored. In this study, we have assessed both stored and circulating TAG levels and egg-to-adult viability in Drosophila melanogaster lines with varying genetic backgrounds established through inbreeding and recombinant inbreeding strategies. We found noticeable variation in egg-to-adult viability and in both stored and circulating TAG levels in D. melanogaster lines. Apparently the D. melanogaster lines with higher levels of circulating TAG also had a higher egg-to-adult viability. To validate this, analysis of these variations through supervised correlation and unsupervised K-means clustering showed that levels of circulating TAG are positively associated with egg-to-adult viability irrespective of gender. The findings suggest that levels of circulating TAG promotes successful transition of egg to an adult. Taken together, the findings not only have a potential application in husbandry of ecologically and economically important insects but also holds importance in translational research in fertility of vertebrates including humans.