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Salazar LC, Ortiz-Reyes A, Rosero DM, Lobo-Echeverri T. Dillapiole in Piper holtonii as an Inhibitor of the Symbiotic Fungus Leucoagaricus gongylophorus of Leaf-Cutting Ants. J Chem Ecol 2020; 46:668-74. [PMID: 32173778 DOI: 10.1007/s10886-020-01170-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 02/07/2020] [Accepted: 03/06/2020] [Indexed: 12/17/2022]
Abstract
Plants of the Piperaceae family are studied for their diverse secondary metabolism with a vast array of compounds that act as chemical defense agents against herbivores. Of all the agricultural pests, the management of insects is a highly significant challenge in the Neotropics, and ants of the Attini tribe pose a major problem. Due to their symbiotic association with the fungus Leucoagaricus gongylophorus (Möller) Singer (Agaricaceae), the species of Atta and Acromyrmex have exhaustive foraging activity which has intensified as deforestation and monoculture farming have increased. The control of leaf-cutting ants is still carried out with synthetic products with negative consequences to the environment and human health. In search for natural and sustainable alternatives to synthetic pesticides, Piper holtonii C. DC. was selected among other plant species after field observations of the foraging activity of Atta cephalotes, which revealed that P. holtonii was never chosen by ants. In vitro evaluation of an ethanol extract of the leaves of P. holtonii resulted in promising inhibitory activity (IC50 102 ppm) against L. gongylophorus. Subsequently, bioassay-guided fractionation led to the isolation of the phenylpropanoid dillapiole, which was also detected in the essential oil. This compound demonstrated inhibition of the fungus with an IC50 of 38 ppm. Considering the symbiotic relationship between the Attini ants and L. gongylophorus, the negative effect on the survival of one of the organisms will affect the survival of the other, so dillapiole or standardized essential oil extracts of P. holtonii containing this active principle could be a unique and useful source as a control agent for leaf cutting-ants.
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Câmara T, Arnan X, Barbosa VS, Wirth R, Iannuzzi L, Leal IR. Disentangling the effects of foliar vs. floral herbivory of leaf-cutting ants on the plant reproductive success of Miconia nervosa (Smith) Triana (Family Melastomataceae). Bull Entomol Res 2020; 110:77-83. [PMID: 31190645 DOI: 10.1017/s0007485319000294] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Flower and leaf herbivory might cause relevant and negative impacts on plant fitness. While flower removal or damage by florivores produces direct negative effects on plant fitness, folivores affect plant fitness by reducing resource allocation to reproduction. In this study, we examine the effects of both flower and leaf herbivory by leaf-cutting ants on the reproductive success of the shrub species Miconia nervosa (Smith) Triana (Family Melastomataceae) in a fragment of Atlantic Forest in Northeast Brazil. We conducted a randomized block-designed field experiment with nine replicates (blocks), in which three plants per block were assigned to one of the three following treatments: undamaged plants (ant exclusion), leaf-damaged plants (ant exclusion from reproductive organs, but not from leaves), and flower + leaf-damaged plants (no exclusion of ants). We then measured flower production, fruit set, and fruit production. Our results showed that flower + leaf-damaged plants reduced flower production nearly twofold in relation to undamaged plants, while flower set in leaf-damaged plants remained constant. The number of flowers that turned into fruits (i.e., fruit set), however, increased by 15% in flower + leaf-damaged plants, while it slightly decreased in leaf-damaged compared to undamaged plants. Contrastingly, fruit production was similar between all treatments. Taken together, our results suggest a prominent role of ant floral herbivory across different stages of the reproductive cycle in M. nervosa, with no consequences on final fruit production. The tolerance of M. nervosa to leaf-cutting ant herbivory might explain its high abundance in human-modified landscapes where leaf-cutting ants are hyper-abundant.
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Affiliation(s)
- T Câmara
- Programa de Pós-Graduação em Biologia Vegetal, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, s/n, Cidade Universitária, 50670-901, Recife, PE, Brazil
| | - X Arnan
- Programa de Pós-Graduação em Biologia Vegetal, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, s/n, Cidade Universitária, 50670-901, Recife, PE, Brazil
- CREAF, Cerdanyola de Vallès, Catalunya, Spain
| | - V S Barbosa
- Programa de Pós-Graduação em Biologia Vegetal, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, s/n, Cidade Universitária, 50670-901, Recife, PE, Brazil
- Centro de Formação de Professores, Universidade Federal de Campina Grande, Rua Sérgio Moreira de Figueiredo, s/n, Casas Populares, CEP: 58900-000, Cajazeiras, Paraíba, Brasil
| | - R Wirth
- Plant Ecology & Systematics, University of Kaiserslautern, PO-Box 3049, 67663 Kaiserslautern, Germany
| | - L Iannuzzi
- Departamento de Zoologia, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego s/no, 50670-901 Recife, PE, Brazil
| | - I R Leal
- Departamento de Botânica, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego s/no, 50670-901 Recife, PE, Brazil
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Fernandez-Bou AS, Dierick D, Harmon TC. Diel pattern driven by free convection controls leaf-cutter ant nest ventilation and greenhouse gas emissions in a Neotropical rain forest. Oecologia 2020; 192:591-601. [PMID: 31989321 DOI: 10.1007/s00442-020-04602-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 01/14/2020] [Indexed: 11/26/2022]
Abstract
Leaf-cutter ant nests are biogeochemical hot spots where ants live and import vegetation to grow fungus. Metabolic activity and (in wet tropical forests) soil gas flux to the nest may result in high nest CO2 concentrations if not adequately ventilated. Wind-driven ventilation mitigates high CO2 concentrations in grasslands, but little is known about exchange for forest species faced with prolonged windless conditions. We studied Atta cephalotes nests located under dense canopy (leaf area index > 5) in a wet tropical rainforest in Costa Rica, where wind events are infrequent. We instrumented nests with thermocouples and flow-through CO2 sensing chambers. The results showed that CO2 concentrations exiting leaf-cutter ant nests follow a diel pattern with higher values at night. We developed an efflux model based on pressure differences that evaluated the observed CO2 diel pattern in terms of ventilation by (1) free convection (warm, less dense air rises out the nest more prominently at night) and (2) episodic wind-forced convection events providing occasional supplemental ventilation during daytime. Average greenhouse gas emissions were estimated through nest vents at about 78 kg CO2eq nest-1 year-1. At the ecosystem level, leaf-cutter ant nest vents accounted for 0.2% to 1% of total rainforest soil emissions. In wet, clayey tropical soils, leaf-cutter ant nests act as free convection-driven conduits for exporting CO2 and other greenhouse gases produced within the nest (fungus and ant respiration, refuse decay), and by roots and soil microbes surrounding the nest. This allows A. cephalotes nests to be ventilated without reliable wind conditions.
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Affiliation(s)
| | - Diego Dierick
- Department of Biological Sciences, Florida International University, Miami, USA
- La Selva Biological Station, Organization for Tropical Studies, Puerto Viejo de Sarapiqui, Costa Rica
| | - Thomas C Harmon
- School of Engineering, Environmental Systems Program, University of California Merced, Merced, CA, USA
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Wells RL, Murphy SK, Moran MD. Habitat Modification by the Leaf-Cutter Ant, Atta cephalotes, and Patterns of Leaf-Litter Arthropod Communities. Environ Entomol 2017; 46:1264-1274. [PMID: 29126135 DOI: 10.1093/ee/nvx162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Indexed: 06/07/2023]
Abstract
Ecosystem engineers are profoundly important in many biological communities. A Neotropical taxonomic group considered to have engineering effects is the Formicidae (ants). Leaf-cutter ants (LCAs), in particular, which form extensive colonies of millions of individuals, can be important ecosystem engineers in these environments. While the effects of LCAs on plant community structure and soil chemistry are well-studied, their effects on consumers are poorly understood. Therefore, we examined the indirect effects of the LCA Atta cephalotes L. on the leaf-litter arthropod community. We compared abundance and diversity patterns at ant nests to areas distant from nests, utilizing both a factorial design and gradient analysis for both nocturnal and diurnal arthropods. We found that arthropod abundance and diversity was significantly lower for multiple taxonomic groups and trophic levels near leaf-cutter nests, and this pattern was strongest at night. Exceptions to this pattern included two morphospecies of Collembola that were more abundant on nests, suggesting some specialization for these species. For the gradient analysis, abundance increased exponentially for most groups of arthropods. However, for the dominant arthropod species, the amphipod Cerrorchestia hyloraina Lindeman, a quadratic function was the best fit curvilinear model for abundance. It appeared that C. hyloraina had maximal abundance at the transition between nest site and less disturbed forest. These results indicate that LCA activity has a strong effect on the leaf-litter arthropod community, adding to spatial heterogeneity within neotropical forests. These effects may translate into changes in important ecological processes such as nutrient cycling and food web function.
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de Man TJB, Stajich JE, Kubicek CP, Teiling C, Chenthamara K, Atanasova L, Druzhinina IS, Levenkova N, Birnbaum SSL, Barribeau SM, Bozick BA, Suen G, Currie CR, Gerardo NM. Small genome of the fungus Escovopsis weberi, a specialized disease agent of ant agriculture. Proc Natl Acad Sci U S A 2016; 113:3567-72. [PMID: 26976598 PMCID: PMC4822581 DOI: 10.1073/pnas.1518501113] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many microorganisms with specialized lifestyles have reduced genomes. This is best understood in beneficial bacterial symbioses, where partner fidelity facilitates loss of genes necessary for living independently. Specialized microbial pathogens may also exhibit gene loss relative to generalists. Here, we demonstrate that Escovopsis weberi, a fungal parasite of the crops of fungus-growing ants, has a reduced genome in terms of both size and gene content relative to closely related but less specialized fungi. Although primary metabolism genes have been retained, the E. weberi genome is depleted in carbohydrate active enzymes, which is consistent with reliance on a host with these functions. E. weberi has also lost genes considered necessary for sexual reproduction. Contrasting these losses, the genome encodes unique secondary metabolite biosynthesis clusters, some of which include genes that exhibit up-regulated expression during host attack. Thus, the specialized nature of the interaction between Escovopsis and ant agriculture is reflected in the parasite's genome.
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Affiliation(s)
- Tom J B de Man
- Department of Biology, Emory University, Atlanta, GA 30322
| | - Jason E Stajich
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521
| | - Christian P Kubicek
- Institute of Chemical Engineering, Vienna University of Technology, 1060 Vienna, Austria
| | | | - Komal Chenthamara
- Institute of Chemical Engineering, Vienna University of Technology, 1060 Vienna, Austria
| | - Lea Atanasova
- Institute of Chemical Engineering, Vienna University of Technology, 1060 Vienna, Austria
| | - Irina S Druzhinina
- Institute of Chemical Engineering, Vienna University of Technology, 1060 Vienna, Austria
| | | | | | - Seth M Barribeau
- Department of Biology, Emory University, Atlanta, GA 30322; Department of Biology, East Carolina University, Greenville, NC 27858
| | | | - Garret Suen
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706
| | - Cameron R Currie
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706
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Rodríguez J, Montoya-Lerma J, Calle Z. Effect of Tithonia diversifolia mulch on Atta cephalotes (Hymenoptera: Formicidae) nests. J Insect Sci 2015; 15:iev015. [PMID: 25843585 PMCID: PMC4535472 DOI: 10.1093/jisesa/iev015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 02/06/2015] [Indexed: 06/04/2023]
Abstract
Recent studies have shown an insecticidal effect of Tithonia diversifolia (Hemsl.) Gray (Asterales: Asteraceae) foliage on workers of Atta cephalotes L. and inhibitory effects of this plant on the growth of the symbiotic fungus Leucoagaricus gongylophorus (A. Müler) Singer. To evaluate the potential of T. diversifolia as a biological control treatment of this important pest, we assessed the effect of green manure (mulch) of this plant on natural nests of A. cephalotes, in Cali, Colombia. Three treatments were randomly assigned to 30 nests: 1) green mulch of T. diversifolia, 2) green mulch of Miconia sp., Ruiz & Pav. and 3) unmulched control. Every 2 wk for 6 mo, the surface of the nests was completely covered with leaves. Physical and chemical parameters of nest soil were assessed before the first and after the last application of the mulch. Ant foraging in T. diversifolia-treated nests decreased by 60% after the initial applications of the mulch, while nest surface area decreased by 40%. When the nests covered with T. diversifolia were opened, it was observed that the superficial fungus chambers had been relocated at a greater depth. In addition, microbial activity and soil pH increased by 84% and 12%, respectively, in nests covered with plant residues. In conclusion, the continued use of T. diversifolia mulch reduces foraging activity and negatively affects the internal conditions of the colonies, thereby inducing the ants to relocate the fungus chambers within the nests.
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Affiliation(s)
- Jonathan Rodríguez
- Department of Biology, Grupo de Ecología de Agroecosistemas y Habitats Naturales (GEAHNA), Universidad del Valle, Calle 13 No. 100-00, Cali, Colombia
| | - James Montoya-Lerma
- Department of Biology, Grupo de Ecología de Agroecosistemas y Habitats Naturales (GEAHNA), Universidad del Valle, Calle 13 No. 100-00, Cali, Colombia
| | - Zoraida Calle
- Restoration Ecology Area, Fundación CIPAV, Carrera 25 No. 6-62, Cali, Colombia
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