Publications

the cellulose-utilizing capability of the fungus cultured by the attine ant atta colombica tonsipes.		1969	5374175
the alkanes of the ant, atta colombica.		1970	5417589
infidelity of leafcutting ants to host plants: resource heterogeneity or defense induction?	leafcutting ants have strong among- and within-plant preferences, and generally abandon plants long before they are completely defoliated. two tropical deciduous forest tree species preferred by the leafcutting ant atta colombica were studied to determine how variation in resource quality affects ant selectivity and partial defoliation of plants. significant differences in palatability and leaf characteristics of spondias mombin and bursera simaruba were found among trees and among leaf types wi ...	1990	28312716
weeding and grooming of pathogens in agriculture by ants.	the ancient mutualism between fungus-growing ants and the fungi they cultivate for food is a textbook example of symbiosis. fungus-growing ants' ability to cultivate fungi depends on protection of the garden from the aggressive microbes associated with the substrate added to the garden as well as from the specialized virulent garden parasite escovopsis. we examined ants' ability to remove alien microbes physically by infecting atta colombica gardens with the generalist pathogen trichoderma virid ...	2001	11375087
a colony-level response to disease control in a leaf-cutting ant.	parasites and pathogens often impose significant costs on their hosts. this is particularly true for social organisms, where the genetic structure of groups and the accumulation of contaminated waste facilitate disease transmission. in response, hosts have evolved many mechanisms of defence against parasites. here we present evidence that atta colombica, a leaf-cutting ant, may combat escovopsis, a dangerous parasite of atta's garden fungus, through a colony-level behavioural response. in a. col ...	2002	12146794
fungal enzymes transferred by leaf-cutting ants in their fungus gardens.	leaf-cutting ants finely fragment the leaf material that they bring to the nest and place faecal droplets on this substrate before incorporating it in the upper part of the fungus-garden. the faecal droplets contain enzymes of which some have been shown to be of fungal origin. here we explicitly address the enzymatic activity of faecal droplets in the leaf-cutting ants acromyrmex echinatior and atta colombica. we used isoelectric focusing and specific staining to show that faecal droplets of bot ...	2004	15035511
sperm storage induces an immunity cost in ants.	ant queens are among the most long-lived insects known. they mate early in adult life and maintain millions of viable sperm in their sperm storage organ until they die many years later. because they never re-mate, the reproductive success of queens is ultimately sperm-limited, but it is not known what selective forces determine the upper limit to sperm storage. here we show that sperm storage carries a significant cost of reduced immunity during colony founding. newly mated queens of the leaf-cu ...	2006	16778889
mating biology of the leaf-cutting ants atta colombica and a. cephalotes.	copulation behavior has often been shaped by sexually selected sperm competition or cryptic female choice. however, manipulation of previously deposited ejaculates is unknown in the social hymenoptera and the degree to which sperm competes after insemination or is actively selected by females has remained ambiguous. we studied the mating process in the leaf-cutting ants atta colombica and a. cephalotes, which belong to one of the few derived social insect lineages where obligate multiple mating ...	2006	16817214
mortality rates and division of labor in the leaf-cutting ant, atta colombica.	division of labor in social groups is affected by the relative costs and benefits of conducting different tasks. however, most studies have examined the dynamics of division of labor, rather than the costs and benefits that presumably underlie the evolution of such systems. in social insects, division of labor may be simplistically described as a source-sink system, with external tasks, such as foraging, acting as sinks for the work force. the implications of two distinct sinks - foraging and wa ...	2006	19537995
plants use macronutrients accumulated in leaf-cutting ant nests.	leaf-cutting ants (atta spp.) are known for their extensive defoliation in neo-tropical forests and savannahs. debate about the costs and benefits of their activities has been largely dominated by their detrimental effects on agriculture and agroforestry. however, the large accumulation of nutrients and changes in soil properties near their nests might benefit plants growing near them. here, we test whether trees use nutrients that accumulate in debris piles near, or refuse chambers within, leaf ...	2007	17164194
specificity in chemical profiles of workers, brood and mutualistic fungi in atta, acromyrmex, and sericomyrmex fungus-growing ants.	neotropical attine ants live in obligatory symbiosis with a fungus that they grow for food on a substrate of primarily plant material harvested by workers. nestmate recognition is likely based on chemical cues as in most other social insects, but recent studies have indicated that both the ants and their mutualistic fungi may contribute to the recognition templates. to investigate the within-colony variation in chemical profiles, we extracted and identified compounds from the cuticle of workers, ...	2007	18040743
optimality in a partitioned task performed by social insects.	biologists have long been aware that adaptations should not be analysed in isolation from the function of the whole organism. here, we address the equivalent issue at the scale of a social insect colony: the optimality of component behaviours in a partitioned sequence of tasks. in colonies of atta colombica, a leaf-cutting ant, harvested leaf tissue is passed from foragers to nest workers that distribute, clean, shred and implant the tissue in fungal gardens. in four laboratory colonies of a. co ...	2008	18782732
individual and collective problem-solving in a foraging context in the leaf-cutting ant atta colombica.	in this paper we investigate the flexibility of foraging behavior in the leaf-cutting ant atta colombica, both at the individual and collective levels, following a change in the physical properties of their environment. we studied in laboratory conditions the changes occurring in foraging behavior when a height constraint was placed 1 cm above part of the trail linking the nest to the foraging area. we found that the size and shape of the fragments of foraging material brought back to the nest w ...	2009	18560906
prudent sperm use by leaf-cutter ant queens.	in many species, females store sperm between copulation and egg fertilization, but the consequences of sperm storage and patterns of sperm use for female life history and reproductive success have not been investigated in great detail. in hymenopteran insect societies (ants, bees, wasps), reproduction is usually monopolized by one or relatively few queens, who mate only during a brief period early in life and store sperm for later use. the queens of some ants are particularly long-lived and have ...	2009	19710057
priority rules govern the organization of traffic on foraging trails under crowding conditions in the leaf-cutting ant atta colombica.	foraging in leaf-cutting ants is generally organized along well-defined recruitment trails supporting a bi-directional flow of outbound and nestbound individuals. this study attempts to reveal the priority rules governing the organization of traffic on these trails. ants were forced to move on a narrow trail, allowing the passage of only two individuals at a time. in this condition, a desynchronization of inbound and outbound traffic was observed, involving the formation of alternating clusters ...	2009	19181897
endophytic fungi reduce leaf-cutting ant damage to seedlings.	our study examines how the mutualism between atta colombica leaf-cutting ants and their cultivated fungus is influenced by the presence of diverse foliar endophytic fungi (endophytes) at high densities in tropical leaf tissues. we conducted laboratory choice trials in which ant colonies chose between cordia alliodora seedlings with high (e(high)) or low (e(low)) densities of endophytes. the e(high) seedlings contained 5.5 times higher endophyte content and a greater diversity of fungal morphospe ...	2011	20610420
effectiveness of seed dispersal by ants in a neotropical tree.	seed dispersal and subsequent recruitment is the template on which forest regeneration takes place. hence, considering the scale over which ecological processes occur is key for understanding the overall impact of various dispersal agents. to explore leafcutter ant (atta colombica) dispersal effectiveness in space and time, seed movement and subsequent recruitment of a large-seeded predominately vertebrate-dispersed tree, simarouba amara (aubl. simaroubaceae), was investigated on barro colorado ...	2011	21910841
do leaf cutting ants cut undetected? testing the effect of ant-induced plant defences on foraging decisions in atta colombica.	leaf-cutting ants (lcas) are polyphagous, yet highly selective herbivores. the factors that govern their selection of food plants, however, remain poorly understood. we hypothesized that the induction of anti-herbivore defences by attacked food plants, which are toxic to either ants or their mutualistic fungus, should significantly affect the ants' foraging behaviour. to test this "induced defence hypothesis," we used lima bean (phaseolus lunatus), a plant that emits many volatile organic compou ...	2011	21799831
random sperm use and genetic effects on worker caste fate in atta colombica leaf-cutting ants.	sperm competition can produce fascinating adaptations with far-reaching evolutionary consequences. social taxa make particularly interesting models, because the outcome of sexual selection determines the genetic composition of groups, with attendant sociobiological consequences. here, we use molecular tools to uncover some of the mechanisms and consequences of sperm competition in the leaf-cutting ant atta colombica, a species with extreme worker size polymorphism. competitive pcr allowed quanti ...	2011	22053996
the allometry of brain miniaturization in ants.	extensive studies of vertebrates have shown that brain size scales to body size following power law functions. most animals are substantially smaller than vertebrates, and extremely small animals face significant challenges relating to nervous system design and function, yet little is known about their brain allometry. within a well-defined monophyletic taxon, formicidae (ants), we analyzed how brain size scales to body size. an analysis of brain allometry for individuals of a highly polymorphic ...	2011	21252471
genetic caste polymorphism and the evolution of polyandry in atta leaf-cutting ants.	multiple mating by females with different males (polyandry) is difficult to explain in many taxa because it carries significant costs to females, yet benefits are often hard to identify. polyandry is a derived trait in social insects, the evolutionary origins of which remain unclear. one of several leading hypotheses for its evolution is that it improves division of labour by increasing intra-colonial genetic diversity. division of labour is a key player in the ecological success of social insec ...	2011	21656003
allometric scaling of foraging rate with trail dimensions in leaf-cutting ants.	leaf-cutting ants (atta spp.) create physical pathways to support the transport of resources on which colony growth and reproduction depend. we determined the scaling relationship between the rate of resource acquisition and the size of the trail system and foraging workforce for 18 colonies of atta colombica and atta cephalotes. we examined conventional power-law scaling patterns, but did so in a multivariate analysis that reveals the simultaneous effects of forager number, trail length and tra ...	2012	22337696
complete genome of serratia sp. strain fgi 94, a strain associated with leaf-cutter ant fungus gardens.	serratia sp. strain fgi 94 was isolated from a fungus garden of the leaf-cutter ant atta colombica. analysis of its 4.86-mbp chromosome will help advance our knowledge of symbiotic interactions and plant biomass degradation in this ancient ant-fungus mutualism.	2013	23516234
complete genome of enterobacteriaceae bacterium strain fgi 57, a strain associated with leaf-cutter ant fungus gardens.	the enterobacteriaceae bacterium strain fgi 57 was isolated from a fungus garden of the leaf-cutter ant atta colombica. analysis of its single 4.76-mbp chromosome will shed light on community dynamics and plant biomass degradation in ant fungus gardens.	2013	23469353
the ejaculatory biology of leafcutter ants.	the eusocial ants are unique in that females (queens) acquire and store sperm on a single mating flight early in adult life. this event largely determines the size (possibly millions of workers), longevity (possibly decades) and genetic variation of the colonies that queens found, but our understanding of the fundamental biology of ejaculate production, transfer and physiological function remains extremely limited. we studied the ejaculation process in the leafcutter ant atta colombica and found ...	2015	25702828
somatic incompatibility and genetic structure of fungal crops in sympatric atta colombica and acromyrmex echinatior leaf-cutting ants.	obligate mutualistic symbioses rely on mechanisms that secure host-symbiont commitments to maximize host benefits and prevent symbiont cheating. previous studies showed that somatic incompatibilities correlate with neutral-marker-based genetic distances between fungal symbionts of panamanian acromyrmex leaf-cutting ants, but the extent to which this relationship applies more generally remained unclear. here we showed that genetic distances accurately predicted somatic incompatibility for acromyr ...	2015	26865859
cellulose-enriched microbial communities from leaf-cutter ant (atta colombica) refuse dumps vary in taxonomic composition and degradation ability.	deconstruction of the cellulose in plant cell walls is critical for carbon flow through ecosystems and for the production of sustainable cellulosic biofuels. our understanding of cellulose deconstruction is largely limited to the study of microbes in isolation, but in nature, this process is driven by microbes within complex communities. in neotropical forests, microbes in leaf-cutter ant refuse dumps are important for carbon turnover. these dumps consist of decaying plant material and a diverse ...	2016	26999749
leaf processing behaviour in atta leafcutter ants: 90% of leaf cutting takes place inside the nest, and ants select pieces that require less cutting.	leafcutter ants cut trimmings from plants, carry them to their underground nests and cut them into smaller pieces before inoculating them with a fungus that serves as a primary food source for the colony. cutting is energetically costly, so the amount of cutting is important in understanding foraging energetics. estimates of the cutting density, metres of cutting per square metre of leaf, were made from samples of transported leaf cuttings and of fungal substrate from field colonies of atta ceph ...	2016	26909161
chemical disguise of myrmecophilous cockroaches and its implications for understanding nestmate recognition mechanisms in leaf-cutting ants.	cockroaches of the genus attaphila regularly occur in leaf-cutting ant colonies. the ants farm a fungus that the cockroaches also appear to feed on. cockroaches disperse between colonies horizontally (via foraging trails) and vertically (attached to queens on their mating flights). we analysed the chemical strategies used by the cockroaches to integrate into colonies of atta colombica and acromyrmex octospinosus. analysing cockroaches from nests of two host species further allowed us to test the ...	2016	27495227
the effects of disturbance threat on leaf-cutting ant colonies: a laboratory study.	the flexibility of organisms to respond plastically to their environment is fundamental to their fitness and evolutionary success. social insects provide some of the most impressive examples of plasticity, with individuals exhibiting behavioral and sometimes morphological adaptations for their specific roles in the colony, such as large soldiers for nest defense. however, with the exception of the honey bee model organism, there has been little investigation of the nature and effects of environm ...	2017	28255181
thermal constraints on foraging of tropical canopy ants.	small cursorial ectotherms risk overheating when foraging in the tropical forest canopy, where the surfaces of unshaded tree branches commonly exceed 50 °c. we quantified the heating and subsequent cooling rates of 11 common canopy ant species from panama and tested the hypothesis that ant workers stop foraging at temperatures consistent with the prevention of overheating. we created hot experimental "sunflecks" on existing foraging trails of four ant species from different clades and spanning a ...	2017	28132105