Faculty of Life and Environmental Sciences, Shimane University, 1060 Nishikawatsu-cho, Matsue, Shimane 690-8504, Japan.
Research Core for Interdisciplinary Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan.
J Insect Sci. 2023 Sep 1;23(5). doi: 10.1093/jisesa/iead078.
Myrmecophytes have mutualistic relationships with symbiotic ants. Although myrmecophytic Macaranga (Malpighiales: Euphorbiaceae) species are well protected by aggressive Crematogaster (Hymenoptera: Formicidae) ants, some bug species occur on the myrmecophytes. To clarify the associations of these bugs with the plants and the ants, we studied the food habits of 3 bug species, Pilophorus lambirensis Nakatani et Komatsu, 2013 (Hemiptera: Miridae: Phylinae), Phylinae sp. 1, and Arbela sp. 1 (Hemiptera: Nabidae). We conducted field observations in a Bornean rainforest. First, we located these bugs and studied their behavioral responses to the ants on Macaranga species; we then conducted stable isotope analyses. All bugs avoided direct contact with ants, but they occurred only on trees with active ants. Pilophorus lambirensis and Phylinae sp. 1 were most commonly observed on the apical parts of host trees, whereas Arbela sp. 1 was mainly in areas distant from the apical parts where ants were sparse. The stable isotope ratios indicated that Phylinae sp. 1 fed on food bodies, which are nutrient-rich spherical bodies produced by Macaranga trees on the apical parts for ants. Although the main diet of the other 2 species remains unclear, nitrogen isotopic signatures demonstrated that P. lambirensis is herbivorous, whereas Arbela sp. 1 is carnivorous. However, the distant location from ants and its isotopic signatures indicated that Arbela sp. 1 rarely fed on the ants. At least 2 mirid bug species might obtain enemy-free space in addition to the food provided by the myrmecophytes.
蚁栖植物与共生蚂蚁之间存在互利关系。虽然受具攻击性的 Crematogaster（膜翅目：蚁科）蚂蚁保护的蚁栖 Macaranga（锦葵目：大戟科）物种得到很好的保护，但一些昆虫物种仍会出现在蚁栖植物上。为了阐明这些昆虫与植物和蚂蚁的联系，我们研究了 3 种昆虫的食性，即 Pilophorus lambirensis Nakatani et Komatsu, 2013（半翅目：沫蝉科：沫蝉亚科）、Phylinae sp. 1 和 Arbela sp. 1（半翅目：盲蝽科）。我们在婆罗洲雨林进行了实地观察。首先，我们定位了这些昆虫，并研究了它们在 Macaranga 物种上对蚂蚁的行为反应；然后进行了稳定同位素分析。所有的昆虫都避免与蚂蚁直接接触，但它们只出现在有活动蚂蚁的树上。Pilophorus lambirensis 和 Phylinae sp. 1 最常出现在宿主树的顶部，而 Arbela sp. 1 主要出现在蚂蚁稀疏的远离顶部的区域。稳定同位素比值表明，Phylinae sp. 1 以食物体为食，这些食物体是 Macaranga 树在顶部为蚂蚁产生的富含营养的球形体。虽然其他 2 种昆虫的主要食物来源尚不清楚，但氮同位素特征表明，P. lambirensis 是食草动物，而 Arbela sp. 1 是肉食性动物。然而，由于其远离蚂蚁的位置及其同位素特征表明，Arbela sp. 1 很少以蚂蚁为食。至少有 2 种沫蝉可能除了从蚁栖植物获得无敌人空间外，还获得了食物。
