Temporal variation in foraging activity and efficiency and the role of hitchhiking behaviour in the leaf-cutting ant, Atta cephalotes

Leaf-cutting ants of the genera Atta and Acromyrmex are at constant risk of epizootics due to their dense living conditions and frequent social interactions between genetically related individuals. To help mitigate the risk of epizootics, these ants display individual and collective immune responses, including associations with symbiotic bacteria that can enhance their resistance to pathogenic infections. For example, Acromyrmex spp. harbor actinobacteria that control infection by Escovopsis in their fungal gardens. Although Atta spp. do not maintain symbiosis with protective actinobacteria, the evidence suggests that these insects are colonized by bacterial microbiota that may play a role in their defense against pathogens. The potential role of the bacterial microbiome of Atta workers in enhancing host immunity remains unexplored. We evaluated multiple parameters of the individual immunity of Atta cephalotes (Linnaeus, 1758) workers, including hemocyte count, encapsulation response, and the antimicrobial activity of the hemolymph in the presence or absence of bacterial microbiota. Experiments were performed on ants reared under standard conditions as well as on ants previously exposed to the entomopathogenic fungus Metharrizium anisopliae. Furthermore, the effects of the presence/absence of bacteria on the survival of workers exposed to M. anisopliae were evaluated. The bacterial microbiota associated with A. cephalotes workers does not modulate the number of hemocytes under control conditions or under conditions of exposure to the fungal pathogen. In addition, infection by M. anisopliae, but not microbiota, increases the encapsulation response. Similarly, the exposure of workers to this fungus led to increased hemolymph antimicrobial activity. Conversely, the removal of bacterial microbiota did not have a significant impact on the survival of workers with M. anisopliae. Our results suggest that the bacterial microbiota associated with the cuticle of A. cephalotes workers does not play a role as a modulator of innate immunity, either at baseline or after exposure to the entomopathogen M. anisopliae. Further, upon infection, workers rely on mechanisms of humoral immunity to respond to this threat. Overall, our findings indicate that the bacterial microbiota associated with A. cephalotes workers does not play a defensive role.

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The role of the Andean uplift as an asymmetrical barrier to gene flow in the Neotropical leaf-cutting ant Atta cephalotes

10.1101/2021.03.24.436865 ◽

2021 ◽

Author(s):

Vanessa Muñoz-Valencia ◽

Glever Alexander Velez-Matinez ◽

James Montoya-Lerma ◽

Fernando Diaz

Keyword(s):

Gene Flow ◽

South America ◽

Management Strategies ◽

Atta Cephalotes ◽

Geographical Barrier ◽

History Of ◽

Andean Uplift ◽

Leaf Cutting ◽

And Migration

Neotropical diversification by the Andean uplift is typically addressed on a large evolutionary scale (e.g. speciation), even though many species are still distributed in both sides of the mountains. The three parallel mountain ranges in the northern Andes (Colombia) impose a major geographical barrier to species' migration from South to Central America. How important these barriers are for conspecific diversification of cross-Andean species such as the leaf-cutting ants remains largely unknown. To answer this question, we studied the mtCOI gene of Atta cephalotes, the most widely distributed leaf-cutting ant species. Our hierarchical analyzes evidenced substantial genetic structure among regions and populations, suggesting a more complex biogeographical history of Andean populations than previously thought. These mountains seem to isolate Central American and Western Colombian populations from the rest of A. cephalotes in South America. Population and migration modelling are consistent with the origin of this species in South America and a major role of the Eastern cordillera as a geographical barrier to historical gene flow, restricting dispersion from north to south. These findings provide insights into the role of the Andean uplift as barrier to gene flow and, eventually, implications for monitoring and designing management strategies for leaf-cutting ants.

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Role of the Andean uplift as an asymmetrical barrier to gene flow in the neotropical leaf‐cutting ant Atta cephalotes

Biotropica ◽

10.1111/btp.13050 ◽

2021 ◽

Author(s):

Vanessa Muñoz‐Valencia ◽

Glever Alexander Vélez‐Matínez ◽

James Montoya‐Lerma ◽

Fernando Díaz

Keyword(s):

Gene Flow ◽

Atta Cephalotes ◽

Andean Uplift ◽

Leaf Cutting

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Variability in the selection of substrate by the leaf-cutting ants atta cephalotes (L.) and acromyrmex octospinosus (Reich) (Formicidae, Attini)

Bulletin of Entomological Research ◽

10.1017/s0007485300005721 ◽

1975 ◽

Vol 65 (1) ◽

pp. 33-47 ◽

Cited By ~ 26

Author(s):

M. Littledyke ◽

J. M. Cherrett

Keyword(s):

Physical Nature ◽

General Level ◽

Chemical Information ◽

Foraging Activity ◽

Atta Cephalotes ◽

Acromyrmex Octospinosus ◽

Leaf Cutting ◽

Laboratory Colonies ◽

Practical Implications ◽

Selection Of

AbstractIn laboratory colonies of Atta cephalotes (L.) and Acromyrmex octospinosus (Reich) pick-up responses to paper discs impregnated with arrestant and inhibitory solutions and feeding responses to measured amounts of these solutions were progressively increased by increasing the concentration of arrestants and decreasing the concentration of inhibitor; the inhibitor had a much greater effect on feeding than on pick-up. Both species picked up paper discs impregnated with arrestants and Acromyrmex readily incorporated these into the fungus garden, while Atta did this less readily. Foraging of arrestive paper discs presented regularly for several days was maintained by Acromyrmex but declined in Atta. Both species were less selective during periods of high foraging activity and during a shortage of suitable substrate. Incoming foragers did not seem to influence the preferences of the outgoing ants, but different colonies showed different preferences. Initially little preference was shown for new materials but on subsequent encounters widely fluctuating preferences emerged, which stabilised within two weeks. Over longer time periods further changes in preferences occurred. The ants' pick-up, cutting or feeding response to a particular material is determined by its chemical and physical nature, the amount of chemical information which the ants obtain, and the threshold of their response. This threshold is modified by such factors as the genetic composition of the colony, the previous quantitative and qualitative availability of the substrate, and the general level of foraging activity. Practical implications of these findings for toxic bait production are discussed.

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Traffic Dynamics of the Leaf-Cutting Ant, Atta cephalotes

The American Naturalist ◽

10.2307/3079079 ◽

2002 ◽

Vol 159 (3) ◽

pp. 283

Author(s):

Burd ◽

Archer ◽

Aranwela ◽

Stradling

Keyword(s):

Atta Cephalotes ◽

Traffic Dynamics ◽

Leaf Cutting

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Rates of growth of the food fungus of the leaf-cutting ant Atta cephalotes (L.) (Hymenoptera: Formicidae) on different substrates gathered by the ants

Bulletin of Entomological Research ◽

10.1017/s0007485300017971 ◽

1979 ◽

Vol 69 (1) ◽

pp. 141-148 ◽

Cited By ~ 7

Author(s):

A. Mudd ◽

G. L. Bateman

Keyword(s):

Nutrient Availability ◽

Plant Material ◽

Growth Inhibitors ◽

Atta Cephalotes ◽

Leaf Extracts ◽

Relative Growth ◽

Relative Growth Rates ◽

Foraging Preferences ◽

Leaf Cutting ◽

Rates Of Growth

AbstractGrowth of the food fungus of the leaf-cutting ant Atta cephalotes (L.) on extracts of plants selected by the ants was shown to be affected by the plant species, the pH of the extract, the concentration of the sap or plant extract and pretreatment of the substrate by the ants. It was not possible to establish an unambiguous relationship between the rate of growth of the fungus on leaf extracts and the foraging preferences of the ants for the leaves. There were indications, however, that the fungus grows most rapidly on extracts of plant material preferred by A. cephalotes. Relative growth rates of the fungus on different substrates may be related to the presence of growth inhibitors rather than to nutrient availability.

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The role of socioeconomic and climatic factors in the spatio-temporal variation of human rabies in China

BMC Infectious Diseases ◽

10.1186/s12879-018-3427-8 ◽

2018 ◽

Vol 18 (1) ◽

Cited By ~ 2

Author(s):

Danhuai Guo ◽

Wenwu Yin ◽

Hongjie Yu ◽

Jean-Claude Thill ◽

Weishi Yang ◽

...

Keyword(s):

Temporal Variation ◽

Climatic Factors ◽

Human Rabies ◽

Spatio Temporal

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Potencial de Formigas (Hymenoptera: Formicidae) como Agentes Anti-herbívoros em Cultivo de Café (Coffea canephora Pierre) e Feijão Guandu [Cajanus cajans (L.) Millsp]

EntomoBrasilis ◽

10.12741/ebrasilis.v6i2.291 ◽

2013 ◽

Vol 6 (2) ◽

pp. 113-118 ◽

Cited By ~ 1

Author(s):

Leandro Xavier Teixeira Chevalier ◽

Diego Silva Gomes ◽

Antonio José Mayhé-Nunes ◽

Jarbas Marçal Queiroz

Keyword(s):

Coffea Canephora ◽

Pigeon Pea ◽

Sugar Solution ◽

Foraging Activity ◽

Organic Management ◽

Coffee Plants

Este trabalho analisou a variação no potencial das formigas como agentes anti-herbívoros em plantas de café (Coffea canephora Pierre) e guandu [Cajanus cajans (L.) Millsp]. Foram usados ovos artificiais, simulando a presença de insetos herbívoros, e solução de açúcar, para aumentar a atividade de formigas, em experimentos de campo. As plantas de café e de guandu possuíam diferentes níveis de atividade de formigas, pois as últimas eram atacadas por membracídeos que atraíam mais formigas. A atividade das formigas foi monitorada após aplicação de solução de açúcar e a remoção de ovos artificiais foi medida após 24 e 48 horas. A solução de açúcar aumentou significativamente a atividade de formigas em plantas de café e de guandu. A remoção dos ovos artificiais foi significativamente maior em ramos com formigas do que sem formigas para as plantas de guandu. A adição de solução de açúcar aumentou a remoção de ovos artificiais em plantas de guandu, mas não em plantas de café. O tratamento com solução de açúcar e a presença de membracídeos em guandu tiveram efeitos similares sobre a atividade de formigas. Este estudo mostrou que a aplicação de solução de açúcar pode ser utilizada para simular a presença de membracídeos sobre as plantas, aumentando a atividade de formigas. Isso permitiu a avaliação de seu potencial como agentes anti-herbívoros, através de experimentos que simulam a presença de insetos sobre as plantas. Potential of Ants (Hymenoptera: Formicidae) as Anti-herbivore Agents in Cultivation of the Coffee (Coffea canephora Pierre) and Pigeon Pea [Cajanus cajans (L.) Millsp] Abstract. This study analyzed the role of ants as anti-herbivore agents in Coffee (Coffea canephora Pierre) and Pigeon Pea [Cajanus cajans (L.) Millsp] plants in agroecosystem under organic management. In these plants we used artificial eggs and sugar solution in experiments that simulated the presence of herbivore insects. Coffee plants did not possess any natural attractive that could intensify foraging activity of ants, but pigeon pea plants were infested by treehoppers which attracted ants. Activity of ants was surveyed after sugar solution application and artificial eggs removal was measured 24 and 48 h after start of the experiments. Sugar solution sprinkled on plants foliage increased significantly the activity of ants on coffee and pigeon pea plants. The removal of artificial eggs was significantly greater in branch with ants than without ants for pigeon pea plants. The sugar solution addiction resulted in greater artificial eggs removal in pigeon pea plants, but not in coffee plants. The treatment with sugar solution and presence of treehoppers had similar effects on the activity of ants on the plants. This study showed that the application of sugar solution can be used to increase activity of ants on plants as well as the potential of ants as anti-herbivore agents can be evaluated in experiments that simulate the presence of insects on the plants.

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THE ROLE OF SUBSURFACE FLOW DYNAMIC ON SPATIAL AND TEMPORAL VARIATION OF WATER CHEMISTRY IN A HEADWATER CATCHMENT

Indonesian Journal of Agricultural Science ◽

10.21082/ijas.v8n1.2007.p17-30 ◽

2016 ◽

Vol 8 (1) ◽

pp. 17

Author(s):

Tadashi Tanaka

Keyword(s):

Water Chemistry ◽

Temporal Variation ◽

Random Process ◽

Riparian Zone ◽

Subsurface Flow ◽

Solute Concentration ◽

Spatial And Temporal Variation ◽

Flow Dynamic ◽

Headwater Catchment

Variation of water chemistry does not merely occur due to in situ chemical process, but also transport process. The study was carried out to address the role of subsurface flow dynamic on spatial and temporal variation of water chemistry in a headwater catchment. Hydrometric and hydrochemistry measurements were done in transect with nested piezometers, tensiometers, and suction samplers at different depths across hillslope and riparian zone in a 5.2 ha first-order drainage of the Kawakami experimental basin, Nagano, Central Japan from August 2000 to August 2001. Spatial variation of solute concentration was defined by the standard deviation and coefficient of variation of the seasonal observed concentrations. Autocorrelation analysis was performed to define temporal variation of solute concentration. The results showed that spatial variation of water chemistry was mainly influenced by the variation of subsurface flow through the hillslope and riparian zone. Solute concentration in the deep riparian groundwater was almost three times higher than that in the hillslope segment. A prominent downward flow in deep riparian groundwater zone provided transport of solutes to the deeper layer. Time series analysis showed that in the deep riparian groundwater, Ca2+, Mg2+, SO42- and HCO3- concentrations underwent a random process, Na+ concentration of a random process superimposed by a trend process, and SiO2 of a random process superimposed by a periodic process. Near the riparian surface, SO42- concentration was composed of a random process superimposed by a periodic process, whereas other solutes were mainly in a random process. In the hillslope soil water, there was no trend observed for the Na+ concentration, but there were for Ca2+ and Mg2+. The magnitude and direction of subsurface flow across hillslope and riparian zone created transport and deposition processes that changed solute concentration spatially and temporally.

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