The curious case of the camelthorn: competition, coexistence and nest-site limitation in a multispecies mutualism

Myrmecophyte plants house ants in domatia in exchange for protection from herbivores. Ant-myrmecophyte mutualisms exhibit two general patterns due to competition between ants for plant occupancy: i) domatia nest-sites are a limiting resource and ii) each individual plant hosts one ant species at a time. However, individual camelthorn trees (Vachellia erioloba) typically host two to four ant species simultaneously, often coexisting in adjacent domatia on the same branch. Such fine-grain spatial coexistence brings into question the conventional wisdom on ant-myrmecophyte mutualisms. Camelthorn ants appear not to be nest-site limited, despite low abundance of suitable domatia, and have random distributions of nest-sites within and across trees. These patterns suggest a lack of competition between ants for domatia and contrast strongly with other ant-myrmecophyte systems. Comparison of this unusual case with others suggests that spatial scale is crucial to coexistence or competitive exclusion involving multiple ant species. Furthermore, coexistence may be facilitated when co-occurring ant species diverge strongly on at least one niche axis. Our conclusions provide recommendations for future ant-myrmecophyte research, particularly in utilising multispecies systems to further our understanding of mutualism biology.

Comparative study in stingless bees (Meliponini) demonstrates that nest entrance size predicts traffic and defensivity

Stingless bees (Meliponini) construct their own species-specific nest entrance. The size of this entrance is under conflicting selective pressures. Smaller entrances are easier to defend; however, a larger entrance accommodates heavier forager traffic. Using a comparative approach with 26 species of stingless bees, we show that species with greater foraging traffic have significantly larger entrances. Such a strong correlation between relative entrance area and traffic across the different species strongly suggests a trade-off between traffic and security. Additionally, we report on a significant trend for higher forager traffic to be associated with more guards and for those guards to be more aggressive. Finally, we discuss the nest entrance of Partamona, known in Brazil as boca de sapo, or toad mouth, which has a wide outer entrance but a narrow inner entrance. This extraordinary design allows these bees to finesse the defensivity/traffic trade-off.

Conservation Land and Human Presence Surrounding Roseate Tern, Lest Tern and Piping Plover Nest Sites in Maine

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Effects of leaves of Ipomoea batatas (Convolvulaceae) on nest development and on respiratory metabolism of leaf-cutting ants Atta sexdens L. (Hym., Formicidae)

Laboratory colonies of the leaf-cutting ants Atta sexdens feed daily with leaves of Ipomoea batatas showed ant mortality and a significant decrease in the size of the fungal garden after the second week, with complete depletion of nests after 5 weeks of treatment. The mean oxygen consumption rate of these ants was higher than the control (ants collected from nests feed with leaves of Eucalyptus alba), suggesting a physiological action of the leaves of I. batatas on the ants in addition to the effect of inhibiting the growth of the fungal garden.

The larval morphology and nest habits of Trypoxylon (Trypargilum) rogenhoferi Kohl 1884 (Insecta: Hymenoptera: Crabronidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The nest architecture of the ant, Pheidole oxyops Forel, 1908 (Hymenoptera : Formicidae)

Pheidole oxyops builds subterranean nests, with an external architecture that is distinctive and easily recognizable by its wide and specific entrance hole, measuring up to 12.2 cm in diameter, denoting a pitfall-trap. In order to study the nests'internal architecture, seven nests were excavated; four were identified with neutral talc, while the others were cast in cement and then excavated. Measurements were made in order to gain a better understanding of their structures, and a photographic documentation was obtained as well. The excavations revealed that the nests are perpendicular relative to the ground, beginning with a cylindrical channel with a mean length of 13.5 cm, containing irregular formations, and whose diameter becomes progressively narrower until the first chamber is formed. As the channel continues, dish-like chambers appear, interconnected by channels that become progressively narrower and longer, while the chambers are arranged at greater distances from each other as nest depth increases. Both channels and chambers are located on the vertical projection of the entrance hole. Nests may reach a depth of up to 5.09 m, with a number of chambers ranging between 4 and 14.

Yeasts isolated from a fungus-growing ant nest, including the description of Trichosporon chiarellii sp nov., an anamorphic basidiomycetous yeast

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Digging effort in leaf-cutting ant queens (Atta sexdens rubropilosa) and its effects on survival and colony growth during the claustral phase

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Nest Digging by Leaf-Cutting Ants: Effect of Group Size and Functional Structures.

Leaf-cutting ant workers dig underground chambers, for housing their symbiotic fungus, interconnected by a vast quantity of tunnels whose function is to permit the entrance of food (leaves), gaseous exchanges, andmovement of workers, offspring, and the queen. Digging is a task executed by a group of workers, but little is known about the group effect and group-constructed functional structures. Thus, we analyzed the structures formed by worker groups (5, 10, 20, and 40 individuals) of the leaf-cutting ant, Atta sexdens rubropilosa, for 2 days of excavation. The digging arena was the same for the 4 groups, with each group corresponding to a different density. Our results verified a pattern of tunneling by the workers, but no chamber was constructed. The group effect is well known, since the 40-worker group dug significantly more than the groups of 5, 10, and 20. These groups did not differ statistically from each other. Analysis of load/worker verified that workers of the smallest group carried the greatest load. Our paper demonstrates the group effect on the digging of nests, namely, that excavation is proportional to group size, but without emergence of a functional structure such as a chamber.

Nest and fledglings of the Red-ruffed Fruitcrow (Pyroderus scutatus)

Information on the breeding behavior of the Red-ruffed Fruitcrow (Pyroderus scutatus) is scarce and restricted to the subspecies P. s. granadensis and P. s. orenocensis. We found the first nest of the nominate subspecies (P. s. scutatus) in an Atlantic Forest area in southeastern Brazil on 28 November 2004. The nest contained two nestlings and was built on a horizontal fork, 16.7 m above ground. It was cup-shaped with a substantial base composed of twigs: outside diameter 38 cm, cup diameter 16.5 cm, outside height 11.3 cm, and inside height 5 cm. The nestlings were thickly covered with brownish down. Only one unknown gender adult visited the nest. Although locally endangered, the breeding cycle of this species remains poorly known.

On the morphology of the worker immatures of the leafcutter ant Atta sexdens linnaeus (Hymenoptera: Formicidae)

Leafcutter ants of the genus Atta Fabricius are serious agricultural pests. Morphological studies of immature stages within this group are few, and the data provided for species of considerable importance are usually incomplete. In this study, the immatures of Atta sexdens Linnaeus are described and compared using light and scanning electron microscopy. Only specimens from founding stage colonies (i.e., lacking adult workers) were used. The existence of four larval instars was estimated by a frequency plot of maximum head widths, and the larvae of different instars differed from each other mainly by their bodily dimensions. Worker larvae belonged to two distinct morphological castes: (1) gardeners and nurses and (2) within-nest generalists. The worker larvae described in this study differed from a previous description of the same species by the following traits: the existence of a genal lobe, the number of clypeal hairs, the presence of two hairs on the ninth abdominal somite, the presence of hairs on the anterior surface of the labrum, and the shape of the maxillary palpus. This study provides a comparative analysis of immature stages of A. sexdens that may be relevant to future morphological and biological studies of the Attini. Microsc. Res. Tech. 75:10591065, 2012. (c) 2012 Wiley Periodicals, Inc.

Density of the tegu lizard (Tupinambis merianae) and its role as nest predator at Anchieta Island, Brazil

Mammals has been pointed out to be the main nest predators in islands, but recent studies has shown that tree snakes are also important nest predator in tropical forests. Here we present information on the density tegu lizards Tupinambis merianae and its role as nest predator at Anchieta Island, Ubatuba, in southeastern Brazil. The mean density of tegu lizards wets estimated to be 83 individuals/km2, which is 1.83 times lower than other well-known population (Fernando de Noronha Archipelago). In the dense rainforest, the density was estimated in 20 individuas/ km2, and in the open rainforest, 109 ind/km2. The high density of this lizard may have serious implications for nest predation. We found that 36% of artificial plasticine eggs were "preyed upon" by tegu lizards. Therefore, it is paramount to manage the tegu population on Anchieta Island to assure the survival of ground nesting birds in islands and possibly in forest fragments.

Conservation puzzle: Endangered hyacinth macaw depends on its nest predator for reproduction

In the Pantanal wetlands of Central Brazil, the endangered hyacinth macaw (Anodorhynchus hyacinthinus), the largest psitacid in the world, makes its nest almost exclusively in natural hollows found in the manduvi tree (Sterculia apetala). The recruitment of manduvis greatly depends on the seed dispersal services provided by the toco toucan (Ramphastos toco), responsible for 83.3% of the seed dispersal. The toco toucan, however, is responsible for about 53% of the preyed eggs, resulting in a case of conflicting ecological pressures in which the reproduction of the hyacinth macaw is indirectly dependent on the seed dispersal services of its nest predator. The case illustrates the intricacies of biotic interactions in species-rich environments where species may be tied by indirect, subtle ecological links which conservationists should be aware of. (c) 2008 Elsevier Ltd. All rights reserved.