Effects of Pine Needle Extracts on the Lifespan of Fruit Fly Drosophila melanogaster

Abstract

Herbivores exert constant selective pressure, and many plants respond by supplying their leaves with an array of chemical defences. Terpenoids, polyphenols, and resin acids top this list, with proven antimicrobial and insecticidal properties. However, little is known about the long-term effects of these compounds on insect lifespan. In this study, we investigated how dietary supplementation with Scots pine ( Pinus sylvestris ) needle extract affects the longevity of the fruit fly ( Drosophila melanogaster ), which is a standard model species for studying longevity, toxicity, and physiology. We used a standard survival assay to test the effects of fly diet with 1% and 5% (w/v) pine extract mixed in and assessed sex-specific responses. We found a significant reduction in lifespan at both concentrations in both sexes. While the females in the control group significantly outperformed males in mean lifespan, this difference disappeared completely after treatment. At higher concentrations, the average lifespan of the insects dropped by about 35–40%. We propose that the apparent decrease in longevity may be related to the antibacterial properties of resin acids and essential oils. Microbiome impairment can lead to energy imbalance and chronic physiological stress, especially in females, requiring large amounts of energy due to reproductive demands. Our results support the hypothesis that pine needle extracts impair insect fitness and highlight the potential of pine needle extracts as environmentally friendly botanical insecticides.