Interactions between leaf-cutting ants, their fungal symbiont (Leucoagaricus) and the endophytic fungi within the vegetation they carry into their colonies are still poorly understood. If endophytes antagonistic to Leucoagaricus were found in plant material being carried by these ants, then this might indicate a potential mechanism for plants to defend themselves from leaf-cutter attack. In addition, it could offer possibilities for the management of these important Neotropical pests. Here, we show that, for Atta sexdens rubropilosa, there was a significantly greater incidence of Trichoderma species in the vegetation removed from the nests—and deposited around the entrances—than in that being transported into the nests. In a no-choice test, Trichoderma-infested rice was taken into the nest, with deleterious effects on both the fungal gardens and ant survival. The endophytic ability of selected strains of Trichoderma was also confirmed, following their inoculation and subsequent reisolation from seedlings of eucalyptus. These results indicate that endophytic fungi which pose a threat to ant fungal gardens through their antagonistic traits, such as Trichoderma, have the potential to act as bodyguards of their plant hosts and thus might be employed in a Trojan-horse strategy to mitigate the negative impact of leaf-cutting ants in both agriculture and silviculture in the Neotropics. We posit that the ants would detect and evict such ‘malign’ endophytes—artificially inoculated into vulnerable crops—during the quality-control process within the nest, and, moreover, that the foraging ants may then be deterred from further harvesting of ‘Trichoderma-enriched’ plants.

Leaf-cutting ants of the genera Acromyrmex and Atta forage vegetation for incorporation into their mutualistic fungal gardens. However, the presence of certain endophytic fungi in this predominantly leaf-based material could affect the fungal garden and thus the choice of material by the ants. The present study was conducted to document the endophytic fungal communities occurring in the vegetation being transported by workers of Atta laevigata into their nests and to compare this community structure with that of the vegetative material subsequently rejected from the nests. We found considerable diversity in the fungi isolated. Acremonium, Cylindrocladium, Drechslera, Epicoccum, Fusarium, Trichoderma, Ulocladium and two unidentified morphospecies were significantly more common in rejected compared with foraged material, and some of these genera include mycoparasites, which could represent a threat to the fungal gardens. Conversely, Colletotrichum, Pestalotiopsis, Phomopsis, Xylaria and an unidentified morphospecies were more common in carried compared with rejected material. The possibility that ants have a 'quality-control' mechanism based on the presence of antagonistic fungal endophytes is discussed, as is the potential use of these fungi as biocontrol agents against Attini pests.

The genus Metrosideros includes several tree, shrub and vine species, native to the Pacific Islands. Seedlings from 25 seed lots of Metrosideros polymorpha and two seed lots of M. tremuloides with symptoms of root rot, stem girdling, wilting and round, purple leaf spots were observed in the Forestry Nursery at the Universidade Federal de Vic ßosa, Brazil. In the original disease site, seedling mortality reached up to 71% in M. polymorpha and 34% in M. tremuloides. Single conidial cultures obtained from infected leaf, root and stem samples of M. polymorpha were used to identify the fungal species. Morphological characters and DNA sequences of four loci, containing partial sequences of b-tubulin (TUB2), histone H3 (HIS3), calmodulin (CAL) and the elongation factor (tef-1a) genes of three isolates, indicated that they belong to a new species, described here as Calonectria metrosideri sp. nov. Potting medium infestation and inoculation of seedlings of M. polymorpha with an inoculum suspension at 1 9 10 4 conidia ml À1 induced typical symptoms of the disease (leaf spots, root rot and wilt), similar to those observed under natural conditions. Calonectria metrosideri was re-isolated, which fulfilled Koch's postulates, and confirmed its status as a pathogen. Material and methods Sampling and fungal isolationSamples of infected plants of M. polymorpha, containing round, purplish leaf spots, and stem cankers and root rot, were collected in the Forest Nursery at the Universidade Federal de Vic ßosa.The samples were kept in a moist chamber at 26°C for 48 h. After incubation, single conidial cultures of the Calonectria sp. were obtained on malt extract agar (MEA) at 26°C for 10 days. Three selected isolates (LPF 101, LPF 103 and LPF 104) used in this study were deposited at CBS Fungal Biodiversity Institute in the Netherlands (CBS), and nomenclatural data were submitted to MycoBank (Crous et al. 2004b). DNA extraction, amplification and purificationMycelia of the respective isolates were scraped from colonized MEA plates and placed separately in 2-ml-microtubes for genomic DNA extraction using the Wizard â Genomic DNA Purification (Promega Corporation, WI, USA) kit. For PCR, the DreamTaq TM Master Mix (MBI Fermentas, Vilnius, Lithuania) was used, following the manufacturer's protocol.Four loci, including fragments of b-tubulin (TUB2), histone H3 (HIS3), elongation factor (tef-1a) and calmodulin (CAL) gene regions were amplified using the primers T1 (O'Donnell and Cigelnik 1997) and CYLTUB1R (Crous et al. 2004a) for

Several species of Calonectria cause diseases on a wide range of forest tree species that are propagated either via seedlings or rooted cuttings. In nurseries these fungi cause damping-off, cutting and root rots, stem lesions, and leaf blights. Recently a Calonectria sp. was isolated from rooted cuttings of Anadenanthera peregrina (Fabaceae), Piptadenia gonoacantha (Fabaceae), and Azadirachta indica (Meliaceae) exhibiting leaf blight and cutting rot in a forest nursery at the Universidade Federal de Viçosa, Brazil. Morphological comparisons and DNA sequences of three loci containing partial gene sequences of β-tubulin (TUB2), calmodulin (CAL), and elongation factor (TEF-1α) indicated that these isolates represent an unnamed species of Calonectria, described here as C. hodgesii sp. nov. Sprayinoculated plants of all three hosts with a suspension at 1x10 4 conidia mL -1 induced leaf lesions, cutting rot, and intense defoliation as observed under natural conditions. Calonectria hodgesii was re-isolated from infected tissue, which fulfilled Koch's postulates and confirmed its status as a pathogen with a wide host range.