The best plant-guarding ants in extrafloral nectaried plants and myrmecophytes according to baiting tests

Extrafloral nectaried plants and myrmecophytes offer resources to ants that may engage in protective mutualisms. The role of different ant species in herbivore deterrence has long been analyzed by using herbivore baits, and ants are regarded as effective plant guards if they attack and/or remove the baits (mostly termites) from plants. Here, we conducted a comparative investigation on which ants display aggression toward baits, which ants are better plant guards, and which plants (extrafloral nectaried plants or myrmecophytes) are better defended by ants. Data from the literature revealed that baiting studies have been performed on 37 extrafloral nectaried plant species and 19 myrmecophytes, and have involved over 30 genera of ants. Extrafloral nectaried plants and myrmecophytes rely on specific ant fauna to defend them from herbivores. In extrafloral nectaried plants, Camponotus and Crematogaster were regarded as the best plant protectors, as they attacked baits in nearly all plants. In myrmecophytes, Azteca, Pheidole and Pseudomyrmex were the most important bait attackers. Myrmecophytes were better protected by ants, as all baits were attacked; in extrafloral nectaried plants, some ants failed to attack the baits. Plants can be patrolled by several different ants, but there is a core of ants that excel in protection, and this varies according to plant type (extrafloral nectaried plants and myrmecophytes). With this knowledge, it may be possible to label different ants as effective plant guards, to anticipate their effects on plant performance and even to understand their potential role as biological control agents.