Department of Entomology, Rutgers University, P.E. Marucci Center, 125A Lake Oswego Road, Chatsworth, NJ, USA.
Instituto Valenciano de Investigaciones Agrarias (IVIA), Centro de Protección Vegetal y Biotecnología, Unidad Mixta Gestión Biotecnológica de Plagas UV-IVIA, Moncada, Valencia, Spain.
Proc Biol Sci. 2020 Sep 30;287(1935):20201080. doi: 10.1098/rspb.2020.1080. Epub 2020 Sep 16.
Plant guttation is a fluid from xylem and phloem sap secreted at the margins of leaves from many plant species. All previous studies have considered guttation as a water source for insects. Here, we hypothesized that plant guttation serves as a reliable and nutrient-rich food source for insects with effects on their communities. Using highbush blueberries as a study system, we demonstrate that guttation droplets contain carbohydrates and proteins. Insects from three feeding lifestyles, a herbivore, a parasitic wasp and a predator, increased their longevity and fecundity when fed on these guttation droplets compared to those fed on control water. Our results also show that guttation droplets, unlike nectar, are present on leaves during the entire growing season and are visited by numerous insects of different orders. In exclusion-field experiments, the presence of guttation modified the insect community by increasing the number of predators and parasitic wasps that visited the plants. Overall, our results demonstrate that plant guttation is highly reliable, compared to other plant-derived food sources such as nectar, and that it increases the communities and fitness of insects. Therefore, guttation represents an important plant trait with profound implications on multi-trophic insect-plant interactions.
植物溢泌是一种从许多植物物种的叶片边缘分泌出来的木质部和韧皮部汁液。所有之前的研究都将溢泌作用视为昆虫的水源。在这里，我们假设植物溢泌是昆虫可靠且富含营养的食物来源，对它们的群落产生影响。我们使用高丛蓝莓作为研究系统，证明溢泌液滴中含有碳水化合物和蛋白质。与对照水相比，三种取食方式的昆虫（一种草食性昆虫、一种寄生蜂和一种捕食性昆虫）在取食这些溢泌液滴时，其寿命和繁殖力都有所提高。我们的研究结果还表明，与花蜜不同，溢泌液滴在整个生长季节都存在于叶片上，并且有许多不同目昆虫访问这些叶片。在排除野外实验中，溢泌液的存在通过增加访问植物的捕食性昆虫和寄生蜂的数量来改变昆虫群落。总的来说，我们的研究结果表明，与其他植物源食物来源（如花蜜）相比，植物溢泌是一种高度可靠的食物来源，并且可以增加昆虫的群落和适应性。因此，溢泌作用代表了一种重要的植物特性，对多营养层昆虫与植物的相互作用具有深远的影响。
