Biotic and Abiotic Interactions Shape Seed Germination of a Fire-Prone Species

Both biotic and abiotic environmental filters drive the occurrence, distribution, and persistence of plant species. Amongst drivers that influence the distribution of plants in harsh environments, seed predation and temperature are particularly important in habitats that are prone to fire. In this study, we highlight the combined effects of predation and high temperature simulating fire to understand its effects on the germination percentage and germination speed of the fire prone species Copaifera oblongifolia. Groups of seeds attacked by the beetles Rhinochenus brevicollis and Apion sp., seeds manipulated by the ant Atta laevigata, and seeds left intact were put to germinate in controlled environments. To evaluate the effects of abiotic filters, seeds with intact elaiosomes and seeds with elaiosomes removed by the ant Atta laevigata were exposed to temperatures of 27, 60, 100, and 200 °C. The results showed that only 2.8% of the seeds attacked by R. brevicollis germinated. Seeds attacked by Apion sp. germinated faster, followed by seeds with their elaiosomes removed and seeds with intact elaiosomes. Seeds attacked by Apion sp. had the lowest germination percentage. The temperature of 200 °C killed seed embryos, whereas seeds exposed to 100 °C took longer to germinate than seeds exposed to other temperatures. Our results reveal that fire intensity and seed damage are important drivers of seed germination of C. oblongifolia.

Aproximación al uso y aprovechamiento de insectos comestibles en las comunidades indígenas del oriente amazónico colombiano

En la Amazonía colombiana, los insectos constituyen un recurso natural abundante, el cual es aprovechado mediante el consumo de especies comestibles. Históricamente, los pueblos indígenas son entomofágicos y han incluido a insectos y otros artrópodos en sus dietas. En el presente estudio, se analiza el uso tradicional de insectos comestibles en las comunidades del oriente amazónico de Colombia. Durante el período de agosto 2020 a marzo 2021, se realizaron entrevistas abiertas y semi-estructuradas a habitantes del municipio de Mitú (Vaupés) y de 41 comunidades indígenas aledañas, las cuales indagaron sobre la percepción, aprovechamiento y comercialización de insectos comestibles. De acuerdo con su valor de uso, Rhynchophorus palmarum (Coleoptera: Curculionidae), Syntermes spinosus (Blattodea: Termitidae), Atta laevigata (Hymenoptera: Formicidae), Lusura chera (Lepidoptera: Notodontidae) y Polybia liliacea (Hymenoptera: Vespidae), constituyen las especies de insectos comestibles más representativas de la región. Para cada especie se estableció su calendario ecológico y se documentaron sus técnicas y métodos de recolecta, sus formas tradicionales de preparación y consumo, y sus actividades de comercialización. Se resalta el potencial de las especies de insectos comestibles analizadas para el fortalecimiento de estrategias de uso sostenible direccionadas a mejorar la seguridad alimentaria de la población y el mantenimiento de los conocimientos tradicionales de las comunidades.

Leaf-cutting ant (Atta laevigata Smith) in an African mahogany plantation in Minas Gerais state, Brazil

Khaya grandifoliola C. DC. (Meliaceae), known as African mahogany, is used in the establishment of commercial plantations for high-value timber production. This work aims to report the first occurrence of the genus Atta in a commercial plantation of this species. An ant nest mound with 105 m2 of loose soil and five active ant holes were observed. Leaves cut into crescent shaped sections and pieces of young branches were found near these holes, in addition to trees with the apical part of their crown partially defoliated. The collected specimens were identified as Atta laevigata Smith (Hymenoptera: Formicidae: Attini), locally known as the glass-head leaf-cutting ant.

Occurrence of Leaf-Cutting and Grass-Cutting Ants of the Genus Atta (Hymenoptera: Formicidae) in Geographic Regions of Brazil

Leaf-cutting ants are widely distributed in Brazil, particularly species of the genus Atta. We therefore described the occurrence of leaf-cutting and grass-cutting ant species of the genus Atta. Five routes comprising some of the main highways in the South, Southeast, Center-West, and North of Brazil were sampled, in addition to ants received from other 82 municipalities, composing 300 municipalities sampled. This is the first comprehensive study of Atta in Brazil. The following species were found: A. laevigata, A. capiguara, A. sexdens rubropilosa, A. sexdens piriventris, A. sexdens sexdens and A. cephalotes. Atta laevigata and A. capiguara were the species present in the largest number of the Brazilian municipalities sampled. Atta laevigata assumed the position of species of greatest occurrence in the Brazilian territory. Atta sexdens piriventris was only recorded in the southern region of Brazil. Atta bisphaerica presented lower expansion than A. capiguara. Atta cephalotes and Atta opaciceps are species of very restricted occurrence. Southeastern region was characterized by the occurrence of A. capiguara and A. laevigata. Atta laevigata exhibited a generalized pattern of occurrence in the Center-West and North. Our study contributes to a better understanding of the so far unknown occurrence of leaf-cutting and grass-cutting ants within Brazil.

First record of the occurrence and abundance of phorids (Diptera: Phoridae) associated with leaf-cutting ants of the genus Atta (Hymenoptera: Formicidae) in the municipality of Cruz das Almas-BA

As formigas cortadeiras do gênero Atta são consideradas uma das principais pragas florestais e agrícolas. Atualmente, o controle químico com iscas granuladas é considerado o mais eficiente, porém, com a adoção inadequada de manejo pode prejudicar organismos não-alvo e o agroecossistema. Parasitóides forídeos têm sido estudados para que possam ser utilizados como estratégia alternativa de manejo para formigas cortadeiras. O uso de forídeos como parte da estratégia de manejo no controle biológico, apesar de ainda ser muito incipiente, pode no futuro se tornar uma alternativa mais segura para o controle de formigas cortadeiras. Assim, o objetivo foi relatar a ocorrência de parasitóides da família Phoridae associados a formigas cortadeiras do gênero Atta no município de Cruz das Almas.Durante os meses de abril a julho, três ambientes foram estudados, sendo: área de pastagem, plantação de eucalipto e um fragmento de Mata Atlântica. Em cada um desses ambientes, foram selecionados três colônias de duas espécies de formigas Atta sexdens sexdens e Atta laevigata. Cada coleta consistiu em seis horas de observação, divididas em oito períodos de 45 minutos. As boas práticas foram feitas nas trilhas e batedores consecutivamente, sempre começando pelo batedor. Um total de 112 forídeos pertencentes a dois gêneros foram coletados, sendo 64 do gênero Eibesfeldtphora e 48 do gênero Myrmosicarius. As boas práticas foram feitas nas trilhas e batedores consecutivamente, sempre começando pelo batedor.Um total de 112 forídeos pertencentes a dois gêneros foram coletados, sendo 64 do gênero Eibesfeldtphora e 48 do gênero Myrmosicarius. As boas práticas foram feitas nas trilhas e batedores consecutivamente, sempre começando pelo batedor. Um total de 112 forídeos pertencentes a dois gêneros foram coletados, sendo 64 do gênero Eibesfeldtphora e 48 do gênero Myrmosicarius.

Survey of leaf-cutting ant species in native vegetation and monocultures in the State of Goiás, Brazil

Leaf-cutting ants are distributed exclusively in the Americas. For this study, we sampled different areas of native vegetation and monocultures to survey the leaf-cutting ants that occur in the State of Goiás, and to what environments they are associated. We recorded six species of leaf-cutting ants: Atta sexdens, Atta laevigata, Acromyrmex subterraneus, Acromyrmex disciger, Acromyrmex ambiguus, and Acromyrmex hispidus. The last four were registered for the first time for the State of Goiás.

An Unprecedented Record of Parasitoidism of Formicidae by a Sarcophagid Fly

The first case of parasitoidism of a Myrmicinae ant by a sarcophagid fly has been observed in the Brazilian Cerrado. The larva of a Helicobia Coquillet (Sarcophagidae) specimen fed on head tissues of an Atta laevigata Smith, 1858 soldier and an adult male fly emerged from a puparium formed outside the host.

Do an ecosystem engineer and environmental gradient act independently or in concert to shape juvenile plant communities? Tests with the leaf-cutter ant Atta laevigata in a Neotropical savanna

Background Ecosystem engineers are species that transform habitats in ways that influence other species.While the impacts of many engineers have been well described, our understanding of how their impact varies along environmental gradients remains limited. Although disentangling the effects of gradients and engineers on biodiversity is complicated—the gradients themselves can be altered by engineers—doing so is necessary to advance conceptual and mathematical models of ecosystem engineering. We used leaf-cutter ants (Atta spp.) to investigate the relative influence of gradients and environmental engineers on the abundance and species richness of woody plants. Methods We conducted our research in South America’s Cerrado. With a survey of plant recruits along a canopy cover gradient, and data on environmental conditions that influence plant recruitment, we fit statistical models that addressed the following questions: (1) Does A. laevigata modify the gradient in canopy cover found in our Cerrado site? (2) Do environmental conditions that influence woody plant establishment in the Cerrado vary with canopy cover or proximity to A. laevigata nests? (3) Do A. laevigata and canopy cover act independently or in concert to influence recruit abundance and species richness? Results We found that environmental conditions previously shown to influence plant establishment in the Cerrado varied in concert with canopy cover, but that ants are not modifying the cover gradient or cover over nests. However, ants are modifying other local environmental conditions, and the magnitude and spatial extent of these changes are consistent across the gradient. In contrast to prior studies, we found that ant-related factors (e.g., proximity to nests, ant changes in surface conditions), rather than canopy cover, had the strongest effect on the abundance of plant recruits. However, the diversity of plants was influenced by both the engineer and the canopy cover gradient. Discussion Atta laevigata in the Cerrado modify local conditions in ways that have strong but spatially restricted consequences for plant communities. We hypothesize that ants indirectly reduce seedling establishment by clearing litter and reducing soil moisture, which leads to seed and seedling desiccation. Altering soil nutrients could also reduce juvenile growth and survivorship; if so these indirect negative effects of engineering could exacerbate their direct effects of harvesting plants. The effects of Atta appear restricted to nest mounds, but they could be long-lasting because mounds persist long after a colony has died or migrated. Our results support the hypothesis that leaf-cutter ants play a dominant role in Cerrado plant demography. We suggest the ecological and economic footprint of these engineers may increase dramatically in coming decades due to the transformation of the Cerrado by human activities.