Pollination of guayule (Parthenium argentatum Gray) by Diptera: Effects on plant development, metabolite production, and reproductive biology

Guayule is a plant with enormous economic potential as an alternative crop in semiarid areas, but its establishment poses challenges. Direct seeding, the most cost-effective method, is hindered by factors such as genetic heterogeneity, lack of optimized seed production systems, and low germination capacity. Limited research exists on the relationship between guayule and pollinators, and their potential impact on guayule performance. The present study assessed the effect of two Diptera species, Sphaerophoria rueppellii and Lucilia sericata , on guayule plant phenology seed production, germination capacity, and biomass and metabolite production. The study compared pollinated by Diptera, non-pollinated and free-pollinated plants under controlled conditions, a first-of-its-kind trial. Results showed that Pollination treatments did not significantly affect seed and biomass production. However, differences in plant maturation and viability, and seed germination capacity were observed among treatments, suggesting a potential influence of pollination on reproductive traits. Moreover, differences in rubber content were also observed, whereas no consistent effects were found for resin or guayulin content. Notably, these effects appeared to be pollinator-specific. These results provide preliminary insights into the potential role of pollinators in guayule performance and highlight a potentially complex interaction between guayule and pollinators. Nevertheless, further research is needed to confirm their agronomic relevance and underlying mechanisms.