Plant Domestication Alters the Nutritional Content of Guttation Droplets with Multi-Trophic Consequences

Domestication often alters plant traits, leading to cascading effects on ecological interactions, particularly in tri-trophic relationships among plants, herbivores, and their natural enemies. While recent studies have investigated the influence of domestication on plant-derived food sources, its effect on guttation-a nutrient-rich exudate produced by many plants-remains unexplored. In this study, we examined the effects of guttation droplets from wild and cultivated highbush blueberries on the fitness (longevity and fecundity) and feeding preferences of three insect species from different trophic guilds: an herbivore (Drosophila suzukii), a parasitoid (Trichopria drosophilae), and a predator (Chrysoperla carnea). Additionally, we analyzed and compared the size and nutritional composition-specifically, total sugar and protein content-of guttation droplets between wild and cultivated blueberry plants. Our results indicated that guttation from wild plants enhanced the longevity of all three insect species, often surpassing that of cultivated plants and diets containing only sugar or sugar plus protein. In choice assays, all three insect species consistently preferred guttation from wild plants over that from cultivated ones. Although the guttation droplets from cultivated plants were larger, those from wild plants contained higher concentrations of sugars (six times more) and proteins (five times more), which likely contributed to the insects' enhanced fitness and preference for wild plant guttation. These findings indicate that domestication has reduced the ecological functionality of guttation in blueberries by potentially influencing tri-trophic interactions. Understanding how domestication affects plant-derived food sources like guttation could have important implications for the conservation of natural enemies in agricultural landscapes.