Abstract: We provide here a checklist of the ants of French Guiana, an overseas department of France situated in northern South America, with a very low human population density and predominantly covered by old-growth tropical rainforests. Based on 165 scientific papers, specimens deposited in collections, and unpublished surveys, a total of 659 valid species and subspecies from 84 genera and 12 subfamilies is presented. Although far from complete, these numbers represent approximately 10% of the ant diversity known to occur in the Neotropical realm. Additionally, three ant genera and 119 species are reported for the first time for French Guiana. Finally, five species are recognized as erroneous records for the the department in the literature. This checklist significantly expands the basic knowledge of the ants in the Guiana Shield, one of the world’s most important biodiversity hotspots.

Abstract: Ants constitute a substantial part of the arthropod biomass in rainforests. Most studies have focused on ground-dwelling ants, which constitute almost half of the diversity of the ant assemblage. We report here the results of the first survey of tree-dwelling ants in French Guiana on a plateau and in a swamp palm forest (Euterpe oleracea Mart.) in the Mitaraka Mountains. We were interested in seeing the effect of topography and geographic distance on species richness and composition and to gather information on the species distribution on tree trunks. The fauna of Mitaraka was compared with one from a site 350 km distant (Petit Saut). In total 105 trees were sampled (30, 30, 45 in the plateau and the swamp forests of Mitaraka, and in Petit Saut plateau forest, respectively). Arboreal ants were attracted using tuna and honey baits spread along a rope reaching an upper branch, except for the palm swamp forest where the baits were only placed at 2 m high. A total of 34, 13 and 22 species were observed in these three respective sites. Six of these species are new records for French Guiana. In Mitaraka Camponotus femoratus (Fabricius, 1804) and Crematogaster leviorLongino, 2003 co-occurred on trees (parabiotic association) and were among the most common species, along with Crematogaster tenuiculaForel, 1904 which was found on other trees (species exclusion). The Mitaraka Mountains appeared more species rich and had a species composition distinct from Petit Saut. Topography also influenced ant species composition. Almost half of the species collected by the baitline method were exclusively foraging in the canopy.

Abstract: Upon advances in sequencing techniques, more and more morphologically identical organisms are identified as cryptic species. Often, mutualistic interactions are proposed as drivers of diversification. Species of the neotropical parabiotic ant association between Crematogaster levior and Camponotus femoratus are known for highly diverse cuticular hydrocarbon (CHC) profiles, which in insects serve as desiccation barrier but also as communication cues. In the present study, we investigated the association of the ants’ CHC profiles with genotypes and morphological traits, and discovered cryptic species pairs in both genera. To assess putative niche differentiation between the cryptic species, we conducted an environmental association study that included various climate variables, canopy cover, and mutualistic plant species. Although mostly sympatric, the two Camponotus species seem to prefer different climate niches. However in the two Crematogaster species, we could not detect any differences in niche preference. The strong differentiation in the CHC profiles may thus suggest a possible role during speciation itself either by inducing assortative mating or by reinforcing sexual selection after the speciation event. We did not detect any further niche differences in the environmental parameters tested. Thus, it remains open how the cryptic species avoid competitive exclusion, with scope for further investigations. © 2019 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

Abstract: Little is known regarding how trophic interactions shape community assembly in tropical forests. Here we assess multi-taxonomic community assembly rules using a rare standardized coordinated inventory comprising exhaustive surveys of five highly-diverse taxonomic groups exerting key ecological functions: trees, fungi, earthworms, ants and spiders. We sampled 36 1.9-ha plots from four remote locations in French Guiana including precise soil measurements, and we tested whether species turnover was coordinated among groups across geographic and edaphic gradients. All species group pairs exhibited significant compositional associations that were independent from soil conditions. For some of the pairs, associations were also partly explained by soil properties, especially soil phosphorus availability. Our study provides evidence for coordinated turnover among taxonomic groups beyond simple relationships with environmental factors, thereby refining our understanding regarding the nature of interactions occurring among these ecologically important groups. © 2019, The Author(s).

Abstract: The unregulated oil exploitation in the Northern Ecuadorian Amazon Region (NEAR), mainly from 1964 to the 90's, led to toxic compounds largely released into the environment. A large majority of people living in the Amazon region have no access to drinking water distribution systems and collects water from rain, wells or small streams. The concentrations of major ions, trace elements, PAHs (polycyclic aromatic hydrocarbons) and BTEX (benzene, toluene, ethylbenzene, xylenes) were analyzed in different water sources to evaluate the impacts of oil extraction and refining. Samples were taken from the NEAR and around the main refinery of the country (Esmeraldas Oil Refinery/State Oil Company of Ecuador) and were compared with domestic waters from the Southern region, not affected by petroleum activities. In most of the samples, microbiological analysis revealed a high level of coliforms representing significant health risks. All measured chemical compounds in waters were in line with national and international guidelines, except for manganese, zinc and aluminum. In several deep-water wells, close to oil camps, toluene concentrations were higher than the natural background while PAHs concentrations never exceeded individually 2 ng·L−1. Water ingestion represented 99% of the total exposure pathways for carcinogenic and non-carcinogenic elements (mainly zinc) in adults and children, while 20% to 49% of the Total Cancer Risk was caused by arsenic concentrations. The health index (HI) indicates acceptable chronic effects for domestic use according the US-EPA thresholds. Nevertheless, these limits do not consider the cocktail effects of metallic and organic compounds. Furthermore, they do not include the social determinants of human exposure, such as socio-economic living conditions or vulnerability. Most (72%) of interviewed families knew sanitary risks but a discrepancy was observed between knowledge and action: religious beliefs, cultural patterns, information sources, experience and emotions play an important role front to exposure. © 2019