The role of α-farnesene in strawberries in insect herbivory and biological control

To address the challenges of climate change and global food security, sustainable agriculture practices are essential, necessitating alternatives to pesticides and chemical fertilizers. Plants have evolved adaptive strategies to defend against herbivorous insects, including the production of volatile organic compounds that serve protective roles and control defense signaling pathways. These plant volatiles play a crucial role in interactions with herbivorous insects, exerting direct toxicity or deterrent effects, functioning as signaling compounds to recruit predators, and priming distant plant tissues for anticipated herbivory. This thesis investigates the contribution of α-farnesene in insect herbivory and biological control using wild strawberry plants (Fragaria vesca), herbivorous insect (Spodoptera littoralis) and the predator species (Chrysoperla carnea) as model organisms. Laboratory-based behavioral assays were conducted to assess the attraction of C. carnea to α-farnesene emitted by S. littoralis-infested leaves, revealing no orientation behavior. Additionally, no-choice feeding experiments compared damage levels in high- and low-α-farnesene producing genotypes, indicating that genotypes with higher α-farnesene concentrations experienced greater damage without affecting the relative growth rate of S. littoralis larvae. Field experiments demonstrated a correlation between higher α-farnesene levels and reduced plant damage, while also showing a potential trade-off with reduced fruit production; however, no significant effect on runner production was observed. These findings highlight the complex nature of plant-insect interactions. Understanding these interactions could potentially contribute to the development of integrated pest management strategies that would minimize reliance on chemical inputs while promoting resilient and environmentally friendly farming systems.