Ziegler, C., Dusenge, M. E., Nyirambangutse, B., Zibera, E., Wallin, G., & Uddling, J. (2020). Contrasting Dependencies of Photosynthetic Capacity on Leaf Nitrogen in Early- and Late-Successional Tropical Montane Tree Species. Front. Plant Sci., 11, 500479.
Abstract: Differences in photosynthetic capacity among tree species and tree functional types are currently assumed to be largely driven by variation in leaf nutrient content, particularly nitrogen (N). However, recent studies indicate that leaf N content is often a poor predictor of variation in photosynthetic capacity in tropical trees. In this study, we explored the relative importance of area-based total leaf N content (Ntot) and within-leaf N allocation to photosynthetic capacity versus light-harvesting in controlling the variation in photosynthetic capacity (i.e. Vcmax, Jmax) among mature trees of 12 species belonging to either early (ES) or late successional (LS) groups growing in a tropical montane rainforest in Rwanda, Central Africa. Photosynthetic capacity at a common leaf temperature of 25˚C (i.e. maximum rates of Rubisco carboxylation, Vcmax25 and of electron transport, Jmax25) was higher in ES than in LS species (+ 58% and 68% for Vcmax25 and Jmax25, respectively). While Ntot did not significantly differ between successional groups, the photosynthetic dependency on Ntot was markedly different. In ES species, Vcmax25 was strongly and positively related to Ntot but this was not the case in LS species. However, there was no significant trade-off between relative leaf N investments in compounds maximizing photosynthetic capacity versus compounds maximizing light harvesting. Both leaf dark respiration at 25˚C (+ 33%) and, more surprisingly, apparent photosynthetic quantum yield (+ 35%) was higher in ES than in LS species. Moreover, Rd25 was positively related to Ntot for both ES and LS species. Our results imply that efforts to quantify carbon fluxes of tropical montane rainforests would be improved if they considered contrasting within-leaf N allocation and photosynthetic Ntot dependencies between species with different successional strategies. © Copyright © 2020 Ziegler, Dusenge, Nyirambangutse, Zibera, Wallin and Uddling.
Keywords: allocation; early successional; late successional; nitrogen; photosynthesis; tropical montane forests
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Dejean, A., Moreau, C. S., Uzac, P., Le Breton, J., & Kenne, M. (2007). The predatory behavior of Pheidole megacephala. C. R. Biol., 330(9), 701–709.
Abstract: We studied the foraging and predatory behaviors of the invasive African myrmicine ant, Pheidole megacephala (F.) in its native range. Workers can singly capture a wide range of insects, including relatively large prey items. For still larger prey, they recruit at short range those nestmates situated within reach of an alarm pheromone and together spread-eagle the insect. These behaviors are complimented by a long-range recruitment (of nestmates remaining in the nest) based on prey size. P. megacephala scouts also use long-range recruitment when they detect the landmarks of termites and competing ant species, thus permitting them to avoid confronting these termites and ants solitarily.
Keywords: Invasive ants; Landmarks; Pheidole megacephala; Predatory behavior; Recruitment; pheromone; ant; behavioral ecology; foraging behavior; invasive species; nest predation; pheromone; predator-prey interaction; animal experiment; ant; article; competitor species; controlled study; foraging behavior; host range; Isoptera; nest predation; nonhuman; predation; predator prey interaction; prey selection; species invasion; worker (insect); Animals; Ants; Feeding Behavior; Female; Isoptera; Predatory Behavior; Social Behavior; Formicidae; Hexapoda; Isoptera; Pheidole megacephala
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Dejean, A., Petitclerc, F., Roux, O., Orivel, J., & Leroy, C. (2012). Does exogenic food benefit both partners in an ant-plant mutualism? the case of Cecropia obtusa and its guest Azteca plant-ants. C. R. Biol., 335(3), 214–219.
Abstract: In the mutualisms involving the myrmecophyte Cecropia obtusa and Azteca ovaticeps or A. alfari, both predatory, the ants defend their host trees from enemies and provide them with nutrients (myrmecotrophy). A. ovaticeps provisioned with prey and then 15N-enriched food produced more individuals than did control colonies (not artificially provisioned). This was not true for A. alfari colonies, possibly due to differences in the degree of maturity of the colonies for the chosen range of host tree sizes (less than 3 m in height). Myrmecotrophy was demonstrated for both Azteca species as provisioning the ants with 15N-enriched food translated into higher δ 15N values in host plant tissues, indicating that nitrogen passed from the food to the plant. Thus, the predatory activity of their guest ants benefits the Cecropia trees not only because the ants protect them from defoliators since most prey are phytophagous insects but also because the plant absorbs nutrients. © 2012 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Keywords: Ant-plant mutualisms; Azteca; Cecropia obtusa; Myrmecotrophy; Stable isotopes
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Mony, R., Dejean, A., Bilong, C. F. B., Kenne, M., & Rouland-Lefèvre, C. (2013). Melissotarsus ants are likely able to digest plant polysaccharides. C. R. Biol., 336(10), 500–504.
Abstract: Melissotarsus ants have an extremely specialized set of behaviours. Both workers and gynes tunnel galleries in their host tree bark. Workers walk with their mesothoracic legs pointing upwards and tend Diaspididae hemiptera for their flesh. The ants use their forelegs to plug the galleries with silk that they secrete themselves. We hypothesised that the ants' energetic needs for nearly constant gallery digging could be satisfied through the absorption of host tree tissues; so, using basic techniques, we examined the digestive capacities of workers from two species. We show that workers are able to degrade oligosaccharides and heterosides as well as, to a lesser degree, polysaccharides. This is one of the rare reports on ants able to digest plant polysaccharides other than starch. © 2013 Académie des sciences.
Keywords: Ant-plant interactions; Degradation of plant material; Enzymatic activity; Melissotarsus ants
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Dejean, A., & Corbara, B. (2014). Reactions by army ant workers to nestmates having had contact with sympatric ant species. C. R. Biol., 337(11), 642–645.
Abstract: It was recently shown that Pheidole megacephala colonies (an invasive species originating from Africa) counterattack when raided by the army ant, Eciton burchellii. The subsequent contact permits Pheidole cuticular compounds (that constitute the “colony odour”) to be transferred onto the raiding Eciton, which are then not recognised by their colony-mates and killed. Using a simple method for transferring cuticular compounds, we tested if this phenomenon occurs for Neotropical ants. Eciton workers rubbed with ants from four sympatric species were released among their colony-mates. Individuals rubbed with Solenopsis saevissima or Camponotus blandus workers were attacked, but not those rubbed with Atta sexdens, Pheidole fallax or with colony-mates (control lot). So, the chemicals of certain sympatric ant species, but not others, trigger intra-colonial aggressiveness in Eciton. We conclude that prey-ant chemicals might have played a role in the evolution of army ant predatory behaviour, likely influencing prey specialization in certain cases.
Keywords: Army ants Antipredation Colony-mate recognition Eciton Transferring cuticular compounds; Eciton; Formicidae
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Dejean, A., Carpenter, J. M., Gibernau, M., Leponce, M., & Corbara, B. (2010). Nest relocation and high mortality rate in a Neotropical social wasp: Impact of an exceptionally rainy La Nina year. C. R. Biol., 333(1), 35–40.
Abstract: After noting the forecast of a La Nina episode, associated with heavy rainfall in French Guiana, we monitored the fate of wasp nests before and during the 2006 short rainy season. The population of the most abundant epiponine wasp species, Polybia bistriata, decreased dramatically during the short rainy season (60.6% of the nests disappeared) then remained low for at least 18 months. Colonies that survived moved from the shelter of large, low leaves (a situation well adapted to the previous dry season) of the most frequent substrate tree, Clusia grandiflora (Clusiaceae), to upper leaves, better ventilated and whose orientation provides good protection from the rain. Therefore, the possibility of moving the nest higher during the first rains following the dry season seems very adaptive as colonies that do not do so are eliminated during the La Nina years, whose frequency will increase with global climate change. (C) 2009 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Keywords: Vespidae; Population size variation; Microevolution; La Nina; French Guiana
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Delabie, J. H. C., Cereghino, R., Groc, S., Dejean, A., Gibernau, M., Corbara, B., et al. (2009). Ants as biological indicators of Wayana Amerindian land use in French Guiana. C. R. Biol., 332(7), 673–684.
Abstract: We examined the ecological impact of traditional land use by Wayana Amerindians in French Guiana using ants as bio-indicators. Ants were sampled through a rapid assessment method and the core results analyzed using Kohonen's self-organizing maps (SOM). Our sample sites included: (1) a Wayana village; (2) a cassava plantation; (3) an abandoned cassava plantation; (4) a forest fragment near the village; (5) a riparian forest; and (6) a primary terra firma forest. The ant diversity decreases according to the decree to which the habitat is disturbed. The SOM allowed us to compare the ecological succession between the six habitats. The protocol used is robust since the same conclusions were drawn using partial data. To cite this article: J.H.C Delabie et al., C R. Biologies 332 (2009). (C) 2009 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Keywords: Landscape ecology; Traditional land use; Formicidae; Rapid assessment; Pit-fall traps; Self-Organizing Maps
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Corbara, B., Carpenter, J. M., Cereghino, R., Leponce, M., Gibernau, M., & Dejean, A. (2009). Diversity and nest site selection of social wasps along Guianese forest edges: assessing the influence of arboreal ants. C. R. Biol., 332(5), 470–479.
Abstract: monitored), and estimate that we recorded up to 73% of the local social wasp fauna. This baseline study was complemented by a long-term survey of the same area and the examination of isolated trees (permitting us to record two additional species, resulting in a total of 63 wasp species). Our results form a continuum from species avoiding nesting on any plant (6.5% of the wasp species) to species nesting on plants but avoiding those sheltering ant nests (82%), to, finally, wasps nesting in association with arboreal ants known to divert army ant raids (11.5%). Consequently, this study documents that most wasp species select plants possibly repulsive to arboreal ants, while associations with arboreal ants, although confirmed here, have been overrepresented in the literature. To cite this article: B. Corbara et al., C. R. Biologies 332 (2009). (C) 2009 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Keywords: Polistinae; Diversity; Nest site selection; Ant-wasp-plant interactions; French Guiana
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McClure, M., Chouteau, M., & Dejean, A. (2008). Territorial aggressiveness on the arboreal ant Azteca alfari by Camponotus blandus in French Guiana due to behavioural constraints. C. R. Biol., 331(9), 663–667.
Abstract: This study reports new information on interactions between two sympatric ant species, the plant-ant Azteca alfari (Dolichoderinae) living in association with the myrmecophyte Cecropia obtusa (Cecropiaceae) and Camponotus blandus (Formicinae), a ground-nesting, arboreal-foraging species. Workers of A. alfari forage only on the foliage and the tipper parts of the trunk of their host Cecropia, while C. blandus nests in the ground but frequently forages and patrols pioneer tree foliage, including Cecropia. The activity pattern of A. alfari and the number of C. blandus on Cecropia obtusa was monitored hourly during a two-day period in a disturbed area in French Guiana. The maximum activity of C. blandus occurred between 8:30 and 12:30, at which time A. alfari had retreated within the domatia and were least present on the trunks. Even though aggressive confrontations were observed, C. blandus workers often initiate confrontations but do not prey on A. alfari nor exploit food bodies produced by Cecropia, the principal food source of A. alfari. Hence hostility appears to be the result of territoriality. Differences in their foraging rhythms are proposed as promoting resource and territory partitioning in this ant assemblage.
Keywords: Azteca alfari (Dolichoderinae); Camponotus blandus (Formicinae); foraging; rhythm of activity; territorial aggressiveness
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Dejean, A., Moreau, C. S., Kenne, M., & Leponce, M. (2008). The raiding success of Pheidole megacephala on other ants in both its native and introduced ranges. C. R. Biol., 331(8), 631–635.
Abstract: We studied the behaviour of the invasive African myrmicine ant, Pheidole megacephala, when confronted with colonies of other common ant species in Cameroon, a part of its native range, and in Mexico, where it has been introduced. P. megacephala raided the nests of the other ants in both cases. Eleven species out of 12 put up a rather strong resistance to raiding P. megacephala workers in Cameroon compared to only three species out of 11 in Mexico, where only colonies of Solenopsis geminata, Dorymyrmex pyramicus and Dolichoderus bispinosus resisted these raids. We conclude that P. megacephala's heightened ability to successfully raid colonies of competing ants may help explain its success and the decline of native ants in areas where it has been introduced.
Keywords: invasive ants; predation; raiding other ants; recruitment
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