The effect of forest fragments on abundance,diversity and species composition of predatory ants in sugarcane fields

Habitat loss and fragmentation have gradually caused loss of diversity and consequently the decline of ecological services. This study aimed to evaluate the effect of tropical forest fragments as natural habitats (river valley fragments and plateau fragments) on the community of predatory and omnivorous ants in nearby sugarcane fields. Twenty fields adjacent to these fragments were selected and evaluated one (dry season) and four months (rainy season) after harvest. In each field, ants were sampled in five linear plots (10 m inside the fragment, 0 m (field path between field and fragment), 5 m, 50 m and 100 m inside the crop fields). Each plot comprised ten sardine baits in a row parallel to the field edge. Species richness and frequency of ant species decreased with increasing distance from the forest fragments. Inside fields, species richness and frequency were higher during the period of vegetative growth (rainy season) than after harvest (dry season). Ant communities of sugarcane fields and forest fragments were more similar later in the season than directly after sugarcane harvest suggesting recolonization of the fields from the fragments. Several ant species were limited to forest fragments after harvest but occurred later in the season also in sugarcane fields confirming the potential contribution of fragments to the recolonization process and therefore to biological control of sugarcane-dominated pest insects.     

Diversity of parasites in Cichlasoma amazonarum Kullander, 1983 during rainy and dry seasons in eastern Amazon (Brazil)

This study investigated the influence of the rainy and dry seasons on the parasite communities of Cichlasoma amazonarum (Kullander, 1983) in a tributary of the Amazon River system, northern Brazil. Of 112 fish examined, 95.5% were parasitized by Ichthyophthirius multifiliis, Piscinoodinium pillulare, Gussevia disparoides, Posthodiplostomum sp., Procamallanus (Spirocamallanus) inopinatus, and Echinorhynchus paranensis, as well as by the Glossiphoniidae leech. Ichthyophthirius multifiliis and P. pillulare were the dominant parasite species, with I. multifiliis the most prevalent and abundant; the leech (Glossiphoniidae) was the least prevalent and least abundant. Parasites presented an aggregate dispersion pattern and seasonal variations in infestation levels, influenced by the environmental conditions in the rainy season. Variation in the parasite dynamics created overall changes in the parasite communities, characterized by greater diversity, species richness and evenness during the rainy season. However, there was a high similarity (99.8%) in the parasite community structure between the rainy and dry seasons. During the dry season the hosts had predominantly 1–3 parasite species compared to 3–4 parasites in the rainy season. Some parasites in the eastern Amazon undergo population changes relating to seasonality. These results thus indicate the correct season to apply adequate prophylactic measures to reduce negative impacts of parasites in this wild ornamental fish when captured.     

Temporal shifts and niche overlapping in <Emphasis Type="Italic">Copestylum</Emphasis> (Diptera,Syrphidae) communities reared in cactus species in a central Mexican scrubland

Semiarid scrubland communities are highly dynamic in terms of their species composition, abundance, and functioning, given the drastic changes in climate among seasons. Spatiotemporal patterns of saprophagous Copestylum (Diptera: Syrphidae) communities in different cactus species richness have not yet been studied, although seasonal changes and plant species richness have been shown to strongly impact the diversity and distribution of many insect communities in scrublands. We analyzed the impact of seasonality and of habitat type (disturbed and undisturbed) on Copestylum communities reared from cactus species at the Barranca de Metztitlán Biosphere Reserve, in central Mexico, by comparing their community structure between seasons and habitats, and assessing the contribution of diversity components for the total diversity of this genus. We also measured patterns of temporal niche overlap among hoverfly species considering their breeding medium. Seasonal variation influenced Copestylum community composition most significantly. Species richness and abundance of Copestylum were higher in the rainy season. Additive partitioning of diversity showed that the main component for species richness is beta diversity between seasons. We detected high niche overlap during the dry season and low overlap during the rainy season. This study provides evidence of temporal shifts in xeric hoverfly communities and suggests that the Copestylum species partition resources over time.     

Contribution of cocoa plantations to the conservation of native ants (Insecta: Hymenoptera: Formicidae) with a special emphasis on the Atlantic Forest fauna of southern Bahia,Brazil

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.     

Leaf shedding and weather in tropical dry-seasonal forest shape the phenology of fungi – Lessons from two years of monthly surveys in southwestern Panama

In the present study, conducted in a secondary dry-seasonal forest in the pacific lowlands of southwestern Panama over 2 years, fungal diversity is linked to plant phenology, litter, and climatic data. Agaricales fungi showed maximum species richness at the beginning of rainy seasons, probably due to the important litter accumulation during the dry season and the increase in humidity favoring fungal growth. Species richness declined during the wet season possibly due to torrential rains, moulds, and decreasing availability of nutrients. Occurrence of foliar pathogenic microfungi correlated negatively with flushing of new leaves at the beginning of the rainy season. Their incidence increased during the wet season and remained high during the dry season. Synchronization of leaf shedding in most tree species significantly reduced the yearly incidence of foliar pathogenic fungi causing an annual turn-over of fungal pathogens that probably contributes to maintain a high diversity of plant pathogenic species.     

Seasonal contrasts in the response of coffee ants to agroforestry shade-tree management

In many tropical landscapes, agroforestry systems are the last forested ecosystems, providing shade, having higher humidity, mitigating potential droughts, and possessing more species than any other crop system. Here, we tested the hypothesis that higher levels of shade and associated humidity in agroforestry enhance coffee ant richness more during the dry than rainy season, comparing ant richness in 22 plots of three coffee agroforestry types in coastal Ecuador: simple-shade agroforests (intensively managed with low tree species diversity), complex-shade agroforests (extensively managed with intermediate tree species diversity) and abandoned coffee agroforests (abandoned for 10-15 yr and resembling secondary forests). Seasonality affected responses of ant richness but not composition to agroforestry management, in that most species were observed in abandoned coffee agroforests in the dry season. In the rainy season, however, most species were found in simple-shade agroforests, and complex agroforestry being intermediate. Foraging coffee ants species composition did not change differently according to agroforestry type and season. Results show that shade appears to be most important in the dry seasons, while a mosaic of different land-use types may provide adequate environmental conditions to ant species, maximizing landscape-wide richness throughout the year.     

Seasonal variation of black fly (Diptera: Simuliidae) species diversity and community structure in tropical streams of Thailand

Seasonal variation of the physicochemical conditions of streams plays an important role in aquatic insect diversity and community structure. Asian tropical streams profoundly change between seasons due to the effects of monsoons. However, little is known about how these changes affect aquatic insect diversity and community structure. The objectives of this study are to examine seasonal variations of the physicochemical conditions in tropical streams in Thailand and to assess the effects of these changes on black fly community structure and diversity. Black flies were sampled and physicochemical conditions recorded at eight sites between December 2007 and December 2008. A total of 10 black fly species were found. Comparisons of the streams between seasons revealed that physical conditions related to rainfall rate were significantly different. Canonical correspondence analysis differentiated sampling sites from each season. Streams in the rainy season were faster and deeper, with higher discharge and conductivity than those of the cold and dry seasons. Species richness was significantly higher in the rainy season than in the cold and dry seasons ( F  = 6.23, P  = 0.004). Community structure profoundly changed between the low-flow season (cold and dry) and high-flow season. Black fly species found predominantly in the low-flow season ( Simulium siamense "cytoform A", S. aureohirtum ) decreased dramatically during the high-flow season. In contrast, species found at high frequency during the high-flow season ( S. nakhonense , S. angulistylum ) disappeared in the low-flow season. The study demonstrates the importance of seasonal variation of stream conditions on black fly community structure and diversity.     

Myrmecofauna of Ironstone Outcrops: Composition and Diversity

The Iron Quadrangle in the state of Minas Gerais, Brazil, harbors ironstone outcrops locally known as cangas, which are historically under great anthropic pressure. The functions performed by ants in environments with severe edapho-climatic conditions, such as cangas, are poorly known. Considering the lack of studies and the potential role of ants in cangas, this study aimed to identify the taxonomic composition of the myrmecofauna that occurs in the soil of two campo rupestre areas (rupestral plant communities) on cangas under different anthropic impacts and evaluate the influence of seasonality and degree of degradation on the diversity and composition of the myrmecofauna. This is the first study to systematically investigate ant fauna collected with baits on ironstone outcrops. Sardine and honey baits were used in dry and rainy periods. Fourteen species distributed among ten genera belonging to five subfamilies were found. The total number of baits visited in the dry season was lower than in the rainy season. Both habitats had a reasonable similarity in their composition (Jaccard similarity index?=?0.571). Multivariate analyses suggest a greater similarity between areas than seasons. The diversity of ants in the cangas is low compared to other Cerrado environments where more than 20 species are frequently collected in these types of study. This low richness may be related to the adverse conditions characteristic of ironstone outcrops. We hope our data will help to expand the actions to manage and preserve cangas in the Iron Quadrangle.     

Immediate impacts of invasion by Wasmannia auropunctata (Hymenoptera: Formicidae) on native litter ant fauna in a New Caledonian rainforest

Abstract For the last 30 years, Wasmannia auropunctata (the little fire ant) has spread throughout the Pacific and represents a severe threat to fragile island habitats. This invader has often been described as a disturbance specialist. Here we present data on its spread in a dense native rainforest in New Caledonia. We monitored by pitfall trapping the litter ant fauna along an invasive gradient from the edge to the inner forest in July 1999 and March 2000. When W. auropunctata was present, the abundance and richness of native ants drops dramatically. In invaded plots, W. auropunctata represented more than 92% of all trapped ant fauna. Among the 23 native species described, only four cryptic species survived. Wasmannia auropunctata appears to be a highly competitive ant that dominates the litter by eliminating native ants. Mechanisms involved in this invasive success may include predation as well as competitive interactions (exploitation and interference). The invasive success of W. auropunctata is similar to that of other tramp ants and reinforces the idea of common evolutionary traits leading to higher competitiveness in a new environment.     

亚热带常绿阔叶林6个常见树种凋落叶在不同降雨期的分解特征

地处长江上游的四川盆地亚热带常绿阔叶林具有典型雨热同季的气候特点,季节性干湿交替可能显著影响凋落物分解,但迄今缺乏相应的报道。因此,采用凋落物分解袋法,研究了常绿阔叶林区最具代表性的马尾松(Pinus massoniana)、柳杉(Cryptomeria fortunei)、杉木(Cunninghamia lanceolata)、香樟(Cinnamomum camphora)、红椿(Toona ciliata)、麻栎(Quercus acutissima)等6种凋落叶在第1年不同雨热季节的分解特征。结果表明,经历1a的分解,6种凋落叶质量残留率大小顺序依次为:红椿(27.90%)柳杉(41.39%)杉木(48.93%)麻栎(49.62%)马尾松(68.82%)香樟(72.23%),6种凋落叶在不同干湿季节质量损失差异显著(P0.05)。阔叶树种在旱季(MRS、SRS和WRS)的质量损失显著高于针叶树种。雨季(ERS和LRS)对6种凋落叶质量损失的贡献率(69.73%—89.68%)均明显大于旱季(10.32%—30.27%)。6种凋落叶在不同时期中质量损失速率差异显著(P0.05),且6种凋落叶在雨季的质量损失速率明显高于旱季。相关分析结果表明,凋落叶质量损失及其速率均与降雨量和温度呈极显著(P0.01)正相关关系。凋落叶质量损失与初始C、木质素含量及C/N、木质素/N极显著(P0.01)负相关,与N含量极显著(P0.01)正相关。这些结果表明亚热带地区森林凋落物分解的质量损失主要发生在雨季,雨季温湿度的改变可显著影响凋落物分解过程。     

Phytoplankton diversity (alpha,beta, and gamma) from the Araguaia River tropical floodplain lakes (central Brazil)

Alpha, beta and gamma are three components of species diversity. Knowing these attributes in floodplain lake phytoplankton communities is vital when selecting conservation areas. Species diversity is commonly used with other taxonomic groups, but rarely with phytoplankton. We compared the number of phytoplankton species (alpha diversity) from 21 Middle Araguaia River floodplain lakes in the 2000 and 2001 rainy and dry seasons. From these samples we estimated complete survey species richness (gamma diversity), quantified differences in species composition between lakes (beta diversity) and assessed the influence of abiotic variables on beta diversity. We recorded a total of 577 taxa. The Sjack1 estimator indicated that 62.31% of taxa were sampled in the 2000 rainy and 67.65% dry seasons, and 68.36% in the 2001 rainy and 73.5% dry seasons. In almost all seasons, alpha diversity negatively correlated with latitude. Beta diversity (β-1) was higher in high water periods, especially in 2000. This may have been caused by isolated heavy rainfall, which would have increased environmental heterogeneity and raised beta diversity. DCA showed differences in phytoplankton composition between rainy and dry seasons in 2000 and 2001, reflecting the influence of flood pulses on phytoplankton composition. The Mantel test indicated spatial distribution patterns where geographically more distant lakes had less-similar phytoplankton communities. Handling editor: J. Padisak     

Positive and negative impact to decomposition of pig cadavers by ants (hymenoptera: Formicidae) at the Islet Yeongdo in Busan,South Korea

We observed how ants affected the decomposition process of pig cadavers. Experiments were carried out with six pig cadavers during three seasons without winter. Fifteen ant species belonging to 14 genera 3 subfamilies were recorded from pig cadavers. The species richness and species composition of ants were different significantly at bloated and decay stages from the remaining stages, regardless of season. Ant species Nylanderia flavipes, Aphaenogaster japonica, Pheidole fervida, and Ectomomyrmex javanus kept hunting a considerable amount of eggs and maggots of flies in the two stages. In particular, Lasius japonicus continually interrupted landing and ovipositing of flies and removed eggs and maggots from pig cadavers. Our observation suggests that ants may affect decomposition process of dead animals by participating in positive and negative ways by massive removal of eggs and maggots of flies.     

Evaluating community effects of a Keystone Ant,Azteca sericeasur,on Inga micheliana leaf litter decomposition in a shaded coffee agro-ecosystem

Our research examined the effect of Azteca sericeasur, a keystone arboreal ant, on the decomposition of leaf litter of the shade tree, Inga micheliana, in coffee agro-ecosystems. This interaction is important in understanding spatial heterogeneity in decomposition. We hypothesized that A. sericeasur could affect leaf litter decomposition by excluding other ants, which could release decomposers, like collembolans, from predation pressure. Determining the relative strengths of these interactions can illuminate the importance of A. sericeasur in decomposition and nutrient cycling processes. We assessed the ant and arthropod communities surrounding 10 pairs of trees, where each pair included one shade tree with an established A. sericeasur nest. Tuna baits were used in conjunction with pitfall traps to assess the ant and arthropod community, and litterbags with I. micheliana leaf litter were used to assess rates of decomposition. The species richness of ants did not change in proximity to A. sericeasur nests, though the ant communities were distinct. Abundance of Collembola and community composition of other invertebrates did not change in the presence of A. sericeasur nests, and there were no differences in leaf litter decomposition rates. This contradicts past studies that suggest A. sericeasur reduces ant species richness in its territory. We suggest that other ants may avoid A. sericeasur by moving within and beneath the leaf litter. Our results indicate that there is no net effect of A. sericeasur on leaf litter decomposition.     

Seasonal variation in abundance and diversity of zooplankton in Asu River,Ebonyi state,Nigeria

The Physicochemical variables and Zooplankton of Asu River, Ebonyi State, Nigeria were studied monthly between October 2013 and June 2014 which covered the wet and dry seasons. The study was carried out monthly in two selected sites by collecting water samples for physiochemical analysis and zooplankton identification. Shannon-Weiner diversity and Margalef's indices were used to determine the zooplankton composition. Investigation on the physiochemical variables showed that water temperature, dissolved oxygen, total dissolved solids, pH, conductivity and carbon (iv) oxide all recorded maximum values in the dry season. The present result also showed that the river is not seriously polluted. However, only carbon (iv) oxide and nitrate varied significantly between seasons (p < 0.05). Forty two (42) zooplankton species comprising Rotifera (7 families; 23 species), Copepoda (2 families; 8 species) and Cladoceran (6 families; 11 species) were identified. Rotifera spp. were numerically dominant and the most diverse group but the crustacean, Thermocyclops oithonoides dominated the total zooplankton biomass during the study. Species abundance showed inverse relationship with species richness, Shannon-Weiner diversity and Evenness. Zooplankton abundance was at its peak in the dry season while species richness, Shannon- Weiner diversity and evenness increased from dry season to wet season.     

Abundance of arbuscular mycorrhizal fungi spores in different environments in a tropical rain forest, Veracruz, Mexico

 The aim of this study was to compare mycorrhizal abundance and diversity in sites with different regimes of disturbance in a tropical rain forest at Los Tuxtlas, Veracruz, Mexico. Arbuscular mycorrhizal spores were quantified at two sites: closed canopy and gaps in the forest. Data were recorded during dry, rainy, and windy ("nortes") seasons. Spores of eight Glomus species, sporocarps of three Sclerocystis species, three species of Acaulospora and two of Gigaspora were found. Significant differences in the number of species and spores were found among seasons. The highest numbers of species and spores were observed during the dry season, with a marked decrease during the rainy season. Our results show that disturbance does not but seasonality does affect abundance and richness of mycorrhizal spores in this tropical wet forest. Accepted: 11 October 1998     

Seasonality affects the parasitism levels in two fish species in the eastern Amazon region

Fish parasite communities have strong interactions with the environment, the host fish, and the aquatic invertebrate communities. Thus, factors directly involving their different life cycles, such as different host populations and environments, as well as seasonal fluctuations in water levels can cause different responses. The main factors structuring parasite communities may be the hydrodynamic variations, together with seasonal variations in the availability of infectious stages of parasites in the environment. The purpose of this study was therefore to investigate the influence of the rainy and dry seasons on parasite infracommunities in fish species in the Amazon River System of Brazil. Between October 2009 and April 2011, specimens of Colossoma macropomum and Colossoma macropomum × Piaractus brachypomus hybrids (tambatinga) were examined for the presence of parasites. The parasite communities were similar in these two species that both showed aggregate dispersion, although the hybrid specimens were less parasitized. For both hosts, the Brillouin diversity, species richness, evenness and Berger‐Parker dominance indices were similar in the rainy season and dry season, except that the Berger‐Parker dominance index for the C. macropomum × P. brachypomus hybrid was higher during the dry season. Ichthyophthirius multifiliis was the dominant parasite, followed by Piscinoodinium pillulare, in both hosts. However, C. macropomum had a higher prevalence and abundance in the dry season, while in the C. macropomum × P. brachypomus hybrid, only the I. multifiliis prevalence increased. The abundance of monogenean species (Anacanthorus spathulatus, Linguadactyloides brinkmanni, Mymarothecium and Notozothecium janauachensis) was higher during the dry season in the gills of C. macropomum. Despite overdispersion of the lernaeid Perulernaea gamitanae, a seasonal pattern was seen only in the C. macropomum × P. brachypomus hybrid, with higher prevalence in the rainy season. The low prevalence and abundance of the ectoparasites Tetrahymena sp., Trichodina sp. and Braga patagonica, as well as of the endoparasites Procamallalus (Spirocamallanus) inopinatus and Neoechinorhynchus buttnerae, were not affected by seasonality. This information is applicable in farming practice for these economically important fish, as it indicates the best time for prophylactic management and treatment against parasites, in order to prevent economic losses in fish farms.     

Impact of the invasive ant Wasmannia auropunctata (Formicidae: Myrmicinae) on local ant diversity in southern Cameroon

The little fire ant, Wasmannia auropunctata Roger, is one of the world's most destructive invasive ants. It has been present in Cameroon for more than four decades, but its impact on local ant diversity is not known. We studied impact of W. auropunctata in three disturbed habitats located in rural and urban areas. We monitored ant diversity in both invaded and noninvaded zones in each area using a combination of three sampling methods: bait, pitfall traps and visual catch in quadrat. We collected 28 species in urban area and 64 in rural area. In invaded zone, W. auropunctata made up 97.72% and 99.96% of all ant fauna and ant species richness decreased to 7 and 2 in urban and rural area, respectively. In accordance with others findings in introduced environments, the presence of W. auropunctata has severely reduced abundance and richness of local ant species in both urban and rural environments in Cameroon. Measures should therefore be put in place to prevent its introduction in natural environment as forest reserves and natural parks.     

Linking scorpion (Arachnida: Scorpiones) assemblage with fragment restoration in the Brazilian Atlantic Forest

Habitat loss due to forest degradation can induce changes in species richness due to variation in species susceptibility to environmental stress. This is particularly important for species with highly specific microhabitats, such as scorpions that inhabit forest habitats. In this study, the richness and abundance of these arachnids were compared between an old-growth (mature) and secondary (65 years under natural restoration) forests. Seasonal influence was also evaluated by comparing diversity between dry and wet seasons. The animals were collected through nocturnal active search using UV lamps and pitfall traps in both areas (old-growth and secondary). Both environments showed similar breast heights of trees, litter depth, litter dry mass, and understory density, indicating a high level of restoration. Scorpion diversity (characterized by Tityus pusillus, T. neglectus, T. brazilae, Bothriurus asper, and Ananteris mauryi) and abundance were not influenced by the different historical usage of both areas. In contrast, the abundance of these arachnids was highly affected by rain regimes, and increased during the dry season. These results suggest that 65 years was a sufficient time period for restoration, making it possible to maintain similar scorpion assemblages in both environments.     

Seasonal abundance and habitat use of bird species in and around Wondo Genet Forest,south‐central Ethiopia

The habitat use and seasonal migratory pattern of birds in Ethiopia is less explored as compared to diversity studies. To this end, this study aimed at investigating the patterns of distribution related to seasonality and the effect of habitat characteristics (elevation, slope, and average vegetation height) on habitat use of birds of Wondo Genet Forest Patch. A stratified random sampling design was used to assess the avian fauna across the four dominant habitat types found in the study area: natural forest, wooded grassland, grassland, and agroforestry land. A point transect count was employed to investigate avian species richness and abundance per habitat type per season. Ancillary data, such as elevation above sea level, latitude and longitude, average vegetation height, and percent slope inclination, were recorded with a GPS and clinometers per plot. A total of 33 migratory bird species were recorded from the area, of which 20 species were northern (Palearctic) migrants while 13 were inter‐African migrants. There was a significant difference in the mean abundance of migratory bird species between dry and wet seasons (t = 2.13, p = .038, df = 44). The variation in mean abundance per plot between the dry and wet seasons in the grassland habitat was significant (t = 2.35, p = .051, df = 7). In most habitat types during both dry and wet seasons, omnivore birds were the most abundant. While slope was a good predictor for bird species abundance in the dry season, altitude and average vegetation height accounted more in the wet season. The patch of forest and its surrounding is an important bird area for migratory, endemic, and global threatened species. Hence, it is conservation priority area, and the study suggests that conservation coupled with ecotourism development is needed for its sustainability.     

Multiple Environmental Controls on Cockroach Assemblage Structure in a Tropical Rain Forest

Arthropod abundance and diversity are remarkable in tropical forests, but are also spatially patchy. This has been attributed either to resources, predators, abiotic conditions or disturbances, but whether such factors may simultaneously shape arthropod assemblage structure is little known. We used cockroaches to test for multiple environmental controls on assemblage structure in 25 km² of Amazonian forest. We performed nocturnal, direct searches for cockroaches in 30 plots (250 m × 2 m) during two seasons, and gathered data on biotic and abiotic factors from previous studies. Cockroach abundance increased with dry litter mass, a measure of resource amount, while species richness increased with litter phosphorus content, a measure of resource availability. Cockroach abundance and species richness decreased with ant relative abundance. Cockroach species composition changed along the gradient of: (1) soil clay content, which correlates with a broad differentiation between flood‐prone and non‐flooded forest; (2) soil relative moisture, consistent with known interspecific variation in desiccation tolerance; and (3) according to the abundance of ants, a potential predator. Turnover in species composition was correlated with abiotic conditions—sorting species according to physiological requirements and to disturbance‐related life history traits—and to ants' selective pressure. Cockroach abundance, diversity, and composition seem to be controlled by distinct sets of environmental factors, but predators which were represented by ants, emerged as a common factor underlying cockroach distribution. Such patterns of community structure may have been previously overlooked by undue focus on single or a few factors, and may be common to tropical forest arthropods.