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.

中文翻译：

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植物内脏为昆虫提供营养丰富的食物

植物内脏是一种来自木质部和韧皮部汁液的液体，这些汁液分泌在许多植物物种的叶子边缘。之前的所有研究都认为内脏是昆虫的水源。在这里，我们假设植物内脏是昆虫可靠且营养丰富的食物来源，对其群落有影响。我们使用高丛蓝莓作为研究系统，证明内脏液滴含有碳水化合物和蛋白质。与以对照水为食的昆虫相比，食草动物、寄生蜂和捕食者这三种喂养方式的昆虫在以这些滴状液滴为食时的寿命和繁殖力增加了。我们的研究结果还表明，与花蜜不同，滴液滴在整个生长季节都存在于叶子上，并被许多不同目昆虫访问。在排除场实验中，内脏的存在通过增加访问植物的捕食者和寄生蜂的数量来改变昆虫群落。总体而言，我们的结果表明，与花蜜等其他植物来源的食物来源相比，植物内脏排泄是高度可靠的，并且它增加了昆虫的群落和适应性。因此，内脏是一种重要的植物性状，对多营养昆虫 - 植物相互作用具有深远的影响。