Most eukaryotic organisms are arthropods. Yet, their diversity in rich terrestrial ecosystems is still unknown. Here we produce tangible estimates of the total species richness of arthropods in a tropical rainforest. Using a comprehensive range of structured protocols, we sampled the phylogenetic breadth of arthropod taxa from the soil to the forest canopy in the San Lorenzo forest, Panama. We collected 6144 arthropod species from 0.48 hectare and extrapolated total species richness to larger areas on the basis of competing models. The whole 6000-hectare forest reserve most likely sustains 25,000 arthropod species. Notably, just 1 hectare of rainforest yields >60% of the arthropod biodiversity held in the wider landscape. Models based on plant diversity fitted the accumulated species richness of both herbivore and nonherbivore taxa exceptionally well. This lends credence to global estimates of arthropod biodiversity developed from plant models.M ost eukaryote species are terrestrial arthropods (1), and most terrestrial arthropods occur in tropical rainforests (2). However, considerably greater sampling effort is required in tropical arthropod surveys to yield realistic estimates of global species richness (3-7). A basic hindrance to estimating global biodiversity lies in a lack of empirical data that establish local biodiversity, which can be scaled up to achieve a global estimate.Although many studies reported species richness for selected groups of well-studied insect taxa, no satisfactory estimate of total arthropod species richness exists for a single tropical rainforest location to date.The unstructured collection and small-scale survey of tropical arthropods cannot yield convincing estimates of total species richness at a specific forest (7-9). Most studies either target few arthropod orders or trophic guilds, or use a limited array of sampling methods, or ignore the diverse upper canopy regions of tropical forests (10-15). Moreover, sampling protocols have rarely been structured in such a way that, with increased sampling, incomplete data on local diversity (7) can be extrapolated to estimate total species richness across multiple spatial scales (16). Where such structured estimates are made, it is invariably for insect herbivores on their host plants (5). However, species accumulation rates may differ markedly for nonherbivore guilds, which include more than half of all described arthropod species (1, 17). As the degree of host specificity (effective specialization) of other guilds can be much lower than that of insect herbivores, or may be driven by different factors (18,19), global estimates based on herbivores alone are questionable. Consequently, extensive cross-taxon surveys with structured protocols at reference sites may be the only effective approach toward estimating total arthropod species richness in tropical forests (3).To provide a comprehensive estimate of total arthropod species richness in a tropical rainforest, we established a collaboration involving 102 researchers with expertise encom...

Trofobiose Entre Formicidae e Hemiptera (Sternorrhyncha e Auchenorrhyncha):Uma Visão Geral RESUMO -Fêz-se uma revisão sobre a relação conhecida como trofobiose e que ocorre de forma convergente entre formigas e diferentes grupos de Hemiptera Sternorrhyncha e Auchenorrhyncha (até então conhecidos como 'Homoptera'). As principais características dos 'Homoptera' e dos Formicidae que favorecem as interações trofobióticas, tais como a excreção de honeydew por insetos sugadores, atendimento por formigas e necessidades fisiológicas dos dois grupos de insetos, são discutidas. Aspectos da sua evolução convergente são apresentados. O sistema mais arcaico não é exatamente trofobiótico, as forrageadoras coletam o honeydew despejado ao acaso na folhagem por indivíduos ou grupos de 'Homoptera' não associados. As relações trofobióticas mais comuns são facultativas, no entanto, esta forma de mutualismo é extremamente diversificada e é responsável por numerosas adaptações fisiológicas, morfológicas ou comportamentais entre os 'Homoptera', em particular Sternorrhyncha. As trofobioses mais diferenciadas são verdadeiras simbioses onde as adaptações mais extremas são observadas do lado dos 'Homoptera'. Ao mesmo tempo, as formigas mostram adaptações comportamentais que resultam de um longo período de coevolução. Considerando-se os insetos sugadores como principais pragas dos cultivos em nível mundial, as implicações das relações trofobióticas são discutidas no contexto das comunidades de insetos em geral, focalizando os problemas que geram em Manejo Integrado de Pragas (MIP), em particular. PALAVRAS-CHAVE:Relações insetos/insetos, relações plantas/insetos, mutualismo, coevolução.ABSTRACT -In this paper, the mutualistic relationship known as trophobiosis, which occurs convergently between ants and several groups of Hemiptera Sternorrhyncha and Auchenorrhyncha (formerly 'Homoptera') is reviewed. The main characteristics of 'Homoptera' and Formicidae which favor trophobiotic interactions, such as honeydew excretion by sapsucking insects, ant attendance and physiological needs of both insects groups, are discussed. Aspects of the convergent evolution are presented. The most archaic system is not trophobiotic per se, foragers collect the honeydew casually expelled on the foliage by individuals or groups of non-associated 'Homoptera'. The commonest trophobiotic relationships are facultative; therefore, this form of mutualism is extremely diversified and is responsible for a range of physiological, morphological and behavioral adaptations by the 'Homoptera', mainly Sternorrhyncha. The more differentiated trophobioses are true symbioses where the most extreme changes can be observed on the 'Homoptera' side. Meanwhile, the ants show mainly behavioral adaptations resulting from a long coevolutive process. Considering the situation of sap-sucking insects as main crop pests worldwide, implications of trophobiotic relationships are discussed in the context of insect communities, in general, and on the problems that imply to Integrated Pest Manage...

By maintaining a forest-like structure, shaded cocoa plantations contribute to the conservation of ants that usually live in the soil, leaf litter or canopy of tropical forests.Here we synthesize the available information on the diversity and community structure of ants in shaded cocoa plantations in the Atlantic forest region of Brazil, compare ant assemblages in cocoa agroforests with forests and other forms of agriculture, and discuss how these shaded plantations contribute to the conservation of the ants in the Atlantic Forest region. We also discuss ants of economical importance and of special interest, including Camponotus, Dolichoderus, Gnamptogenys, Pachycondyla, Pseudomyrmex and other litter dwelling genera. We discuss the situation of the tramp ant Wasmannia auropunctata in the Bahian cocoa-producing region where it is considered as native, and that of the two cryptobiotic genera Thaumatomyrmex and Typhlomyrmex, as well as that of proven and possible endangered army ant and Ponerini species. A total of 192 ant species from four strata were found in extensive sampling of a cocoa plantation with a relatively simple shade canopy (comprised primarily of Erythrina). Species richness in the cocoa plantations corresponded roughly to that of low diversity native forests, and species composition of cocoa plantations was most similar to native habitats (forest and mangroves) while ant composition in other agricultural habitats was most similar to that of urban areas. Although occurrences of Wasmannia auropunctata were similar in cocoa plantations and forests, abundance of Thaumatomyrmex and Typhlomyrmex, generally thought to be rare ants, was relatively high in cocoa plantations. These results, from cocoa plantations with relatively simple shade, demonstrate the importance of cocoa for ant conservation in the Atlantic forest region of Brazil. It is likely that cocoa plantations with a greater number of vegetation strata and higher tree species richness (such as traditional cabruca plantations) provide even more important habitat for ants generally and for ant species of conservation concern.

In southern Bahia, Brazil, large land areas are used for the production of cocoa (Theobroma cacao), which is predominantly grown under the shade of native trees in an agroforestry system locally known as cabruca. As a dominant forest-like landscape element of the cocoa region, the cabrucas play an important role in the conservation of the region's biodiversity. The purpose of this review is to provide the scientific basis for an action plan to reconcile cocoa production and biodiversity conservation in southern Bahia. The available research collectively highlights the diversity of responses of different species and biological groups to both the habitat quality of the cabrucas themselves and to the general characteristics of the landscape, such as the relative extent and spatial configuration of different vegetation types within the landscape mosaic. We identify factors that influence directly or indirectly the occurrence of native species in the cabrucas and the wider landscape of the cocoa region and develop recommendations for their conservation management. We show that the current scientific knowledge already provides a good basis for a biodiversity friendly management of the cocoa region of southern Bahia, although more work is needed to refine some management recommendations, especially on shade canopy composition and density, and verify their economic viability. The implementation of our recommendations should be accompanied by appropriate biological and socioeconomic monitoring and the findings should inform a broad program of adaptive management of the cabrucas and the wider cocoa landscape.

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Reproduction systems are controlling the creation of new genetic variants as well as how natural selection can operate on these variants. Therefore, they had historically been one of the main foci of evolutionary biology studies. The little fire ant, Wasmannia auropunctata, has been found to display an extraordinary reproduction system, in which both males and female queens are produced clonally. So far, native sexual populations of W. auropunctata have not been identified. Our goals were to identify such sexual populations and investigate the origins of female parthenogenesis and male clonality. Using mitochondrial DNA and microsatellite markers in 17 native populations, we found that traditional sexual populations occurred in W. auropunctata and are likely the recent source of neighboring clonal populations. Queen parthenogenesis has probably evolved several times through mutational events. Male clonality is tightly linked to queen parthenogenesis and thus appears to be female controlled. Its origin could be accounted for by 2 mutually exclusive hypotheses: either by the expected coevolution of the 2 sexes (i.e., a variant of the maternal genome elimination hypothesis) or by a shared mechanistic origin (i.e., by the production of anucleate ovules by parthenogenetic queens). Our results also show that W. auropunctata males and females do not form separate evolutionary units and are unlikely to be engaged in an all-out battle of sexes. This work opens up new perspectives for studies on the adaptive significance and evolutionary stability of mixed sexual and clonal reproduction systems in living organisms.

Quantifying the spatio-temporal distribution of arthropods in tropical rainforests represents a first step towards scrutinizing the global distribution of biodiversity on Earth. To date most studies have focused on narrow taxonomic groups or lack a design that allows partitioning of the components of diversity. Here, we consider an exceptionally large dataset (113,952 individuals representing 5,858 species), obtained from the San Lorenzo forest in Panama, where the phylogenetic breadth of arthropod taxa was surveyed using 14 protocols targeting the soil, litter, understory, lower and upper canopy habitats, replicated across seasons in 2003 and 2004. This dataset is used to explore the relative influence of horizontal, vertical and seasonal drivers of arthropod distribution in this forest. We considered arthropod abundance, observed and estimated species richness, additive decomposition of species richness, multiplicative partitioning of species diversity, variation in species composition, species turnover and guild structure as components of diversity. At the scale of our study (2km of distance, 40m in height and 400 days), the effects related to the vertical and seasonal dimensions were most important. Most adult arthropods were collected from the soil/litter or the upper canopy and species richness was highest in the canopy. We compared the distribution of arthropods and trees within our study system. Effects related to the seasonal dimension were stronger for arthropods than for trees. We conclude that: (1) models of beta diversity developed for tropical trees are unlikely to be applicable to tropical arthropods; (2) it is imperative that estimates of global biodiversity derived from mass collecting of arthropods in tropical rainforests embrace the strong vertical and seasonal partitioning observed here; and (3) given the high species turnover observed between seasons, global climate change may have severe consequences for rainforest arthropods.

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