Singh Akanksha, Mayer Veronika E, Zytynska Sharon E, Hesse Benjamin, Weisser Wolfgang W
Chair for Terrestrial Ecology, Department of Ecology and Ecosystem Management, Technische Universität München, Freising, Germany.
Agricultural Ecology Group, Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland.
Front Plant Sci. 2021 Mar 15;12:627570. doi: 10.3389/fpls.2021.627570. eCollection 2021.
Pearl bodies are produced by some plant species as food reward for ants and in exchange, ants defend these plants against insect pests. Sap-sucking pests such as aphids also excrete honeydew as food reward for ants, leading to potential conflict where ants could preferentially defend either the plant or the aphid. How pest insects might influence plant pearl body production, is yet to be investigated. Okra is a widely consumed vegetable worldwide and is attacked by the ant-tended cotton aphid. The plants produce pearl bodies, which are predominantly found on the underside of the leaves and formed from epidermal cells. We conducted a set of field and greenhouse experiments to explore plant-aphid-ant interactions, their influence on pearl body production and resulting performance of okra plants, across okra varieties. We found that ants of genus, which are dominant in okra fields, preferred pearl bodies over aphid honeydew; although, their highest abundance was recorded in presence of both these food rewards, and on one okra variety. Removal of pearl bodies from the plants increased their production; however, plant growth and chlorophyll content were negatively associated with pearl body replenishment. Potentially to mitigate this resource cost, plants developed such a novel defense response because we found that aphid presence reduced pearl body production, but only when there were no ants. Finally, aphids negatively affected plant performance, but only at very high densities. As aphids also attract ants, plants may tolerate their presence at low densities to attract higher ant abundances. Our study highlights that plants can adapt their defense strategies in pest presence for efficient resource use. We suggest that understanding pearl body associated interactions in crop plants can assist in using such traits for pest management.
珍珠体是一些植物物种产生的，作为对蚂蚁的食物奖励，作为交换，蚂蚁保护这些植物免受害虫侵害。吸食汁液的害虫如蚜虫也会分泌蜜露作为对蚂蚁的食物奖励，这就导致了潜在的冲突，即蚂蚁可能会优先保护植物或蚜虫。害虫如何影响植物珍珠体的产生，还有待研究。秋葵是一种在全球广泛食用的蔬菜，受到蚂蚁照料的棉蚜的攻击。这些植物会产生珍珠体，主要分布在叶片的下表面，由表皮细胞形成。我们进行了一系列田间和温室实验，以探索秋葵品种间植物-蚜虫-蚂蚁的相互作用、它们对珍珠体产生的影响以及秋葵植株的最终表现。我们发现，秋葵田中占主导地位的某属蚂蚁更喜欢珍珠体而不是蚜虫的蜜露；尽管如此，在同时存在这两种食物奖励的情况下，以及在一个秋葵品种上，它们的数量最多。去除植物上的珍珠体会增加其产量；然而，植物生长和叶绿素含量与珍珠体的补充呈负相关。为了潜在地减轻这种资源成本，植物产生了这样一种新的防御反应，因为我们发现蚜虫的存在会减少珍珠体的产生，但只有在没有蚂蚁的情况下才会如此。最后，蚜虫对植物表现有负面影响，但只有在密度非常高时才会如此。由于蚜虫也会吸引蚂蚁，植物可能会容忍它们在低密度时的存在，以吸引更多的蚂蚁。我们的研究强调，植物可以在有害生物存在的情况下调整其防御策略，以实现资源的有效利用。我们建议，了解作物中与珍珠体相关的相互作用有助于利用这些特性进行害虫管理。
