Sakata Itaru, Hayashi Masayuki, Nakamuta Kiyoshi
Graduate School of Horticulture, Chiba University, Matsudo, Chiba, 271-8510, Japan.
Hokkaido Agricultural Research Center (HARC), National Agriculture and Food Research Organisation (NARO), Sapporo, Hokkaido, 062-8555, Japan.
J Chem Ecol. 2017 Oct;43(10):966-970. doi: 10.1007/s10886-017-0891-3. Epub 2017 Oct 4.
In mutualisms, partner discrimination is often the most important challenge for interacting organisms. The interaction between ants and aphids is a model system for studying mutualisms; ants are provided with honeydew by aphids and, in turn, the ants offer beneficial services to the aphids. To establish and maintain this system, ants must discriminate mutualistic aphid species correctly. Although recent studies have shown that ants recognize aphids as mutualistic partners based on their cuticular hydrocarbons (CHCs), it was unclear which CHCs are involved in recognition. Here, we tested whether the n-alkane or methylalkane fraction, or both, of aphid CHCs were utilized as partner recognition cues by measuring ant aggressiveness toward these fractions. When workers of Tetramorium tsushimae ants were presented with dummies coated with n-alkanes of their mutualistic aphid Aphis craccivora, ants displayed higher levels of aggression than to dummies treated with total CHCs or methyl alkanes of A. craccivora; responses to dummies treated with n-alkanes of A. craccivora were similar to those to control dummies or dummies treated with the CHCs of the non-mutualistic aphid Acyrthosiphon pisum. By contrast, ants exhibited lower aggression to dummies treated with either total CHCs or the methylalkane fraction of the mutualistic aphid than to control dummies or dummies treated with CHCs of the non-mutualistic aphid. These results suggest that T. tsushimae ants use methylalkanes of the mutualistic aphid's CHCs to recognize partners, and that these ants do not recognize aphids as partners on the basis of n-alkanes.
在互利共生关系中，伙伴识别往往是相互作用的生物体面临的最重要挑战。蚂蚁与蚜虫之间的相互作用是研究互利共生关系的一个模型系统；蚜虫为蚂蚁提供蜜露，反过来，蚂蚁为蚜虫提供有益的服务。为了建立和维持这个系统，蚂蚁必须正确识别互利共生的蚜虫种类。尽管最近的研究表明，蚂蚁基于蚜虫的表皮碳氢化合物（CHCs）将蚜虫识别为互利共生伙伴，但尚不清楚哪些CHCs参与了识别过程。在这里，我们通过测量蚂蚁对这些组分的攻击性，测试了蚜虫CHCs的正构烷烃或甲基烷烃组分，或两者，是否被用作伙伴识别线索。当给对马大头蚁工蚁呈现涂有其互利共生蚜虫豆蚜正构烷烃的假虫时，蚂蚁表现出比对涂有豆蚜总CHCs或甲基烷烃的假虫更高的攻击性；对涂有豆蚜正构烷烃的假虫的反应与对对照假虫或涂有非互利共生蚜虫豌豆蚜CHCs的假虫的反应相似。相比之下，蚂蚁对涂有互利共生蚜虫总CHCs或甲基烷烃组分的假虫的攻击性比对对照假虫或涂有非互利共生蚜虫CHCs的假虫的攻击性更低。这些结果表明，对马大头蚁利用互利共生蚜虫CHCs中的甲基烷烃来识别伙伴，并且这些蚂蚁不会基于正构烷烃将蚜虫识别为伙伴。
