Ants have efficient and well-studied social immunity mechanisms, which prevent the colony contamination. Little is known about how workers keep their outside territory clear of diseases. We investigated the interactions between Azteca chartifex ants, their associated bacteria and bacteria on the phyllosphere of Byrsonima sericea trees, comparing plants patrolled and not by the ants. The hypothesis is that bacteria associated with the worker’s exoskeleton may outcompete the leaf bacteria. Culturable bacteria were isolated from ants, from the main and satellite nests, and from phyllosphere of B. sericea taken from trees that had A. chartifex nests and from trees without nests. The isolates were grouped by Gram guilds and identified at the genus level. There was a higher percentage of Gram-negative isolates in the ants and on the leaves patrolled by them. There was a higher growth rate of ant bacteria from the main nest compared to those found in ants from the satellite nests. The most representative genus among ant isolates was Enterobacter, also found on leaves patrolled by ants. Under favourable in vitro conditions, A. chartifex Gram-negative bacteria outcompete leaf bacteria by overgrowth, showing a greater competition capacity over the Gram-positive bacteria from leaves with no previous interaction with ants in the field. It was demonstrated that ants carry bacteria capable of outcompeting exogenous bacteria associated with their outside territory. The leaf microbiota of a patrolled tree could be shaped by the ant microbiota, suggesting that large ant colonies may have a key role in structuring canopy plant–microbe interactions.

蚂蚁具有有效且经过充分研究的社会免疫机制，可以防止菌落污染。关于工人如何保持其外部区域免受疾病侵害知之甚少。我们调查了Azteca chartifex蚂蚁，它们的相关细菌以及Byrsonima sericea树的叶球上的细菌之间的相互作用，比较了被蚂蚁巡逻的植物和非蚂蚁巡逻的植物。假设是与工人外骨骼相关的细菌可能会胜过叶片细菌。培养细菌从蚂蚁孤立的，从主卫星巢，并从叶围B.绢从有树木采取A. chartifex巢和没有巢的树木。分离株按革兰氏公会分组，并在属水平上鉴定。在蚂蚁和它们巡逻的叶子上，革兰氏阴性菌的比例更高。与从卫星巢中的蚂蚁中发现的相比，来自主要巢中的蚂蚁细菌的生长速率更高。蚂蚁分离株中最具代表性的属是肠杆菌，也发现在蚂蚁巡逻的叶子上。在有利的体外条件下，沙棘曲霉革兰氏阴性菌通过过度生长而胜过叶细菌，表现出比叶片中的革兰氏阳性菌更大的竞争能力，而以前在田间没有与蚂蚁相互作用。事实证明，蚂蚁携带的细菌能够胜过与其外部区域相关的外源细菌。蚂蚁菌群可以塑造出巡逻树的叶子菌群，这表明大型蚁群可能在构建冠层植物与微生物的相互作用中起着关键作用。