Foraging and nesting behavior of leafcutter ants (Atta cephalotes) in a tropical secondary forest


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Foraging and nesting behavior of leafcutter ants (Atta cephalotes) in a tropical secondary forest

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Foraging and nesting behavior of leafcutter ants (Atta cephalotes) in a tropical secondary forest
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Asentamiento de colonias y comportamiento de forrajeo de hormigas cortadoras de hojas (Atta cephalotes) en un bosque tropical secundario
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Carson, John Wade
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La Calandria Forest is a coffee plantation-turned-reforestation project located in Los Llanos, Monteverde, Costa Rica. One of the species that seems to be successful in this forest is Atta cephalotes leaf cutter ants (Hymenoptera: Formicidae). I studied A. cephalotes foraging and nesting behavior to better understand their ecological relationships within a tropical forest ecosystem. I recorded the location of A. cephalotes nests and foraging sites with a GPS, and then identified plant species that these leaf cutter ants foraged from. After collecting data for two weeks: I created a map of A. cephalotes nests and their corresponding foraging sites, calculated foraging distances for each nest, calculated the nest density of an 11-hectacre segment of La Calandria, and analyzed the foraged plant species composition. I concluded that: 1) Most A. cephalotes nests resided either in clearings or along the forest edge. 2) Different ant colonies never crossed paths, and avoided foraging in each other’s territory. 3) La Calandria had an A. cephalotes nest density of 1.55 nests/ha. This is higher than values commonly found for tropical primary forest, but lower than the nest densities of forests adjacent to agriculture. 4) A. cephalotes foraged from a variety of plant species, but Inga punctata comprised 26.4% of the targeted forage sites. 5) On average, larger nests (33m) traveled farther than smaller nests (18m) to forage from plants. ( , )
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El bosque de La Calandria es un proyecto de reforestación de una antigua plantación de café ubicada en Los Llanos, Monteverde, Costa Rica. Una de las especies que parece tener éxito en este bosque son las hormigas cortadoras de hojas Atta cephalotes (Hymenoptera: Formicidae). Estudié el comportamiento de forrajeo y asentamiento de colonias de A. cephalotes para comprender mejor sus relaciones ecológicas dentro de un ecosistema de bosque tropical. Con un GPS, registré la ubicación de los nidos de A. cephalotes y la ubicación de las plantas de donde forrajean e identifiqué las especies de plantas de las cuales forrajean. Después de recopilar datos durante dos semanas, creé un mapa de nidos de A. cephalotes y sus sitios de forrajeo correspondientes, calculé las distancias totales de forrajeo para cada nido, calculé la densidad de nidos de un segmento de 11 hectáreas de La Calandria y analicé la composición de las especies de plantas que las hormigas forrajean. Llegué a la conclusión de que: 1) La mayoría de los nidos de A. cephalotes se ubican en claros o a lo largo del borde del bosque. 2) Las diferentes colonias de hormigas nunca se cruzaron, y evitaron buscar alimento en el territorio de cada una. 3) La Calandria tenía una densidad de nidos de A. cephalotes de 1.55 nidos / ha. Esto es más alto que los valores comúnmente encontrados para los bosques primarios tropicales, pero más bajos que las densidades de nidos de bosques adyacentes terrenos de agricultura. 4) A. cephalotes se alimentaron de una gran variedad de especies de plantas, pero Inga punctata comprendió el 26,4% del total de plantas forrajeadas. 5) En promedio, los nidos más grandes viajaron más lejos (33 m) que los nidos más pequeños (18 m) para forrajear de las plantas.
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Student affiliation : Department of Biological Sciences, University of California, San Diego
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1 Foraging and Nesting Behavior of Leafcutter Ants ( Atta cephalotes ) in a Tropical Secondary Forest John Wade Carson Department of Biological Sciences , University of California, San Diego U C EAP Tropical Biology and Conservation Spring 2019 7 June 2019 A BSTRACT La Calandria Forest is a coffee plantation turned reforestation project located in Los Llanos, Monteverde, Costa Rica. One of the species that seems to be successful in this forest is Atta cephalotes leaf cutter ants (Hymenoptera: Formicidae). I studied A. cephalotes foraging and nesting behavior to better understand their ecological relationships within a tropical forest ecosystem. I recorded the location of A. cephalotes nests and foraging sites with a GPS , and then identified plant species that these leaf cutter ants foraged from. After collecting data for two weeks: I created a map of A. cephalotes nests and their corresponding foraging sites, calculated foraging distances for each nest, calcul ated the nest density of an 11hectacre segment of La Calandria, and analyzed the foraged pla nt species composition. I concluded that: 1) Most A. cephalotes nests resided either in clearings or along the forest edge. 2) Different ant colonies never crossed paths, and avoided foraging in each other’s territory. 3) La Calandria had an A. cephalotes nest density of 1.55 nests/ha. This is higher than values commonly found for tropical primary forest, but lower than the nest densities of forests adjacent to agriculture. 4) A. cephalotes foraged from a variety of plant species, but Inga punctata comprise d 26.4% of the targeted forage sites. 5) On average, larger nests (33m) traveled farther than smaller nests (18m) to forage from plants. Asentamiento de colonias y comportamiento de forrajeo de hormigas cortadoras de hojas ( Atta cephalotes ) en un bosque tropical secundario RESUMEN El bosque de La Calandria es un proyecto de reforestacin de una antigua plantacin de caf ubicada en Los Llanos, Monteverde, Costa Rica. Una de las especies que parece tener xito en este bosque son las hormigas cortadoras de hojas Atta cephalotes (Hymenoptera: Formicidae). Estudi el comportamiento de forrajeo y asentamiento de colonias de A. cephalotes para comprender mejor sus relaciones ecolgicas dentro de un ecosistema de bosque tropical. Con un GPS, registr la ubicacin de los nidos de A. cephalotes y la ubicacin de las plantas de donde forrajean e identifiqu las especies de plantas de las cuales forrajean. Despus de recopilar datos durante dos semanas, cre un mapa de nidos de A. cephalotes y sus sitios de forrajeo correspondientes, calcul las distancias totales de forrajeo para cada nido, calcul la densidad de nidos de un segmento de 11 hectareas de La Calandria y analic la composicin de las especies de plantas que las hormigas forrajean. Llegu a la conclusin de que: 1) La mayora de los nidos de A. cephalotes se ubican en claros o a lo largo del borde del bosque. 2) Las diferentes colonias de hormigas nunca se cruzaron, y evitaron buscar alimento en el territorio de cada una. 3) La Calandria tena una densidad de nidos de A. cephalotes de 1.55 nidos / ha. Esto es ms alto que los valores comnmente encontrados para los bosques primarios tropicales, pero ms bajos que las densidades de nidos de bosques adyacentes terrenos de agricultura. 4) A. cephal otes se

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Foraging and Nesting Behavior of Atta cephalotes Carson 2 alimentaron de una gran variedad de especies de plantas, pero Inga punctata comprendi el 26,4% del total de plantas forrajeadas. 5) En promedio, los nidos ms grandes viajaron ms lejos (33 m) que los nidos ms pequeos (18 m) para forrajear de l as plantas. Leafcutter ants are the dominant herbivore of the Neotropics, consuming over 12 percent of the tropic’s leaf production every year. Instead of eating the leaves, however, leafcutter ants use the leaves as a substrate to grow fungus within their nest. One leafcutter ant of particular interest to the Monteverde region is Atta cephalotes. This leafcutter ant has the widest distribution of all the leafcutter ants , located all the way from Brazil and Ecuador to the s outhern portion of Mexico. A. cephalotes feed from a wide variety of crops throughout the region, making them a worrisome pest to farmers throu ghout South and Central America ( H lldobler & Wilson, 1990). Due to their foraging behavior, A. c ephalotes possess a strong ecological relationship with the plants in their ecosystem. Active nests lead to a lower biodiversity and a reduced abundance of understory plants near their n est ( Garrettson et al. 1998). Additionally, A. cephalotes prefer to forage from the high canopies and from newer leaves. (Cherret 1968,T. Lewis et al 1974, and Nichols Orians and Schultz 1989) They also prefer to forage from leaves high in Nitrogen and Phosphor us, but low in Magnesium and Aluminum , ( B erish 1986). Multiple researchers have noted that A. cephalotes forage from a wide variety of plant species within their ecosystems ( Blanton and Ewel 1985, and Cherrett 1968). These l eaf cutter ants prefer to forage from plants close to their nest, but a large proportion of their foraging effort actually occurs between 31.3m and 46.8m away from their nests (Cherrett 1968). Nest density, measured in nests per hectare, is a common metric to quantitatively evaluate the prevalence of leafcutter ants in a forested area, and may be a good indicator of forest health. Vasconcelos ( 1995) observed a negative correlation between the ma turity of a forest and its leafcutter nest density. In the Brazilian Amazon, he observed that p rimary forests had the smallest nest density, followed by older secondary forest, while young secondary forest showed the greatest nest density. The nest density of leafcutter ants is extremely high in agricultural areas (Leston 1978 and Jaffe 1986), likely due to the fact that leafcutter ants tend to form nests in open clearings ( Jaffe 1989) . It appears that many leafcutter ant species, such as A. cephalotes , can be considered gap specialists (H lldobler & Wilson, 1990). Res earchers have also observed that A. Cephalotes prefer to build their nests on the edge of a forest compared to the ce nter of a forest (Wirth et al. 2007 and Meyer et al. 2009). In my study, I conducted research on the A. c ephalotes population of La Calandria Forest in Monteverde, Costa Rica. This coffee plantation turned reforestation project now has had some regeneration and reforestation plots growing for over 50 years, while some areas have been growing for less than two years. In my study I aimed to learn more about these leaf cutter ants’ foraging preferences and nesting patterns within the context of a secondary T ropical Forest e cosystem.

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Foraging and Nesting Behavior of Atta cephalotes Carson 3 I produced and analyzed the following four research questions: 1) Where in La Calandria will A. cephalotes nests be the most present? Other research suggests that a forest edge effect increases the presence of A. cephalotes colonies, so I hypothesize that I will observe more nests in open areas or on the forest edge. 2) What will be the nest density of La Calandria , and how will this compare to nest densities researchers have found for primary forest and forested areas adjacent to agriculture ? Because La Calandria is a recovering secondary forest, I hypothesize it will hold a greater nest density than primary forests, but hold a lower nest density than agricultural areas. Based on values for nest density found in other studies, I hypothesize that La Calandria will have a ne st density between 0.5 and 3 nests/ha. 3) W hich plant species will A. c ephalotes forage from at La Calandria Forest Reserve, and how will this compare to what A. cephalotes forage from in other ecosystems? Other research suggests A. Cephalotes forage from a variety of plants, but focus most of their foraging effort on a small subset of species. I hypothesize that I will find a similar trend in my study. I also anticipate that the A. cephalotes of La Calandria will forage from different set of p lants than the A. cephalotes of other e cosystems, likely due to a difference in plant composition of its env ironment. 4) Will larger A. cephalotes colonies travel a further distance to forage than smaller colonies? Other research suggests this trend ( Cherr et 1968), and I hypothesiz ed that I would find similar results in my study. MATERIALS AND METHODS I conducted my research over a 13day period from May 7, 2019 to May 19, 2019. The search for foraging sites occurred on a daily basis at various hours between 8:00AM and 11:30 PM. F irst, I walked through the trails and understory of La Ca landria Forest Reserve to locate A. c e phalotes nests in the reserve. I recorded nest locations with marking tape and a GPS receiver so that I could later calculate foraging distances for each nest , but also create a map of all forage and net sites. As I tracked colony locations I took note of their size. I def ined a large nest as having a large spoils pile around the nest, while everything else was considered as a small nest. After I finished locating the colonies, I began to follow the ant trails from their colonies to their re spective foraging locations . When explicit visual evidence of leafcutter foraging was observed, I marked the site with flagging tape and recorded its location with a GPS recei ver . Explicit visual evidence qualified as either 1) A. c ephalotes traveling dow n a plant with organic matter , 2) observing A. c ephalotes cut leaf pieces from a plant , or 3) observing A. cephalotes carry organic matter from the ground to their nest. An expert in plant taxonomy, Eladio Cruz, helped identify the foraged plant species. W ith the assistance of Randy Chinchilla, I calculated t h e distance from each nest to their r e spective foraging sites using their GPS coordinates . Randy Chinchilla also created a map of La Calandria with all observed colonies and foraging sites. The GPS had a minimum error of 3 meters. This error could cause a high percentage of error for shorter distances. To compensate, I measured foraging distances to the nearest decimeter if the foragi ng distance was less than 5 meters away or if there was no significant fo l iage between the nest and its forage site. I excluded the foraging distance data from one nest because I could not locate the nest’s precise location, and therefore its GPS marker was inaccurate.

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Foraging and Nesting Behavior of Atta cephalotes Carson 4 RESULTS Nes ting Location Within the 11hectare area of La Calandria I surveyed, I observed 17 A. cephalotes nests ( Figure 2 ) . Nine of the 17 nests resided near the forest edge or with in the clearing at the Field Station . It also appears the nests have a reduced presence within the middle of the forest , whi ch includes some of the older secondary plots ( Figure 1 ). My results support my hypothesis. Additionally, I observed that A. cephalotes avoided other A. cephalotes colonies, but they also avoided the paths and foraging sites of other A. cephalotes colonies . Nest Density I calculated a nest density of 1.55 nests/hectare within this 11 hectare segment of La Calandria (17nests/11hectares). This fragment of forest holds a greater nest density than undisturbed primary forest s ( Table 2 ) . Perfecto and coworkers (1993) found a nest density as high as 0.71 in a tropical primary rainforest in Puerto Viejo, Costa Rica. Meyer found a nest density as l ow as 2.4 nests per hectare on the forest edge near sugarcane monoculture in Coimbra, Brazil . My nests/ha value of 1.55 does not resemble nest densities found for tropical primary forest, nor does it represent the nest densities of forests near agriculture. I hypothesized I would find a nest density between 0.5 and 3 nests/ha. I conclude that m y hypothesis was supported b y my data . Foraging Behavior: Plant Species I observed 87 foraging sites, 82 of which were plants. A. cephalotes foraged from 24 species of trees within 21 different plant families . T hree plant species made up 43.6% of the foraged plants in La Calandria . Specifically, they targeted 23 Inga Punctata (26.4%), eight Conostegia xalapensis (9.2%) , and seven Zanthoxylum fagara (8.0%) ( Table 1 ) . A. c ephalotes from La Calandria displayed both differences and similarities to the foraging behavior of A. cephalotes in other ecosystems. ( Table 3 ) . Blanton and Ewel (1985) found that A. cephalotes strongly preferred to forage from Manihot esculenta in a tropical wet forest of Tue rialba, Costa Rica. Cherret ( 1968 ) observed that A. cephalotes preferred to forage from Terminalia amazonica and Eschweilera corrugate with in a tropical W allaba forest of Bartica, Guyana. Both of these other studies also observed that A. cephalotes foraged from a variety of plant species, but focused a large proportion of their effort on a sm all subset of plant species. Blanton and Ewel (1985) obse rved A. cephalotes foraging Trema micrantha, Cecropia obtusifolia, and Croton spp., three species that A. cephalotes also foraged in La Calandria. N o mutual foraged plant species occur r ed between my study and Cherret’s (1968) study. I conclude that my data supports my hypothesis. Foraging Behavior: Foraging Distance In large colonies, A. cephalotes traveled 33 meters on average to their foraging sites. Smaller colonies traveled 18 meters on average to their foraging sites ( Figure 3 ) . This difference was statistically significant (T =2.83, p=.006) . I conclude that this data supports my hypothesis.

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Foraging and Nesting Behavior of Atta cephalotes Carson 5 Fig. 1 : Map of the 11 hectare study site. The grey boxes (middle left) represent the field station. Black dashes represent hiking trails.

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Foraging and Nesting Behavior of Atta cephalotes Carson 6 Fig. 2 : Map of surveyed area with nest locations and foraged trees. Each dot represents an A. cephalotes nest. Each tree icon represents a foraging site. Nests are color coded to correspond with their respective foraging sites and to differentiate themselves from other nests. This image does not include the 19 foraging sites that had their distances measured by hand. White nest have no foraging sites recorded with GPS. I excluded the orange nest (top left) from the forage distance calculations.

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Foraging and Nesting Behavior of Atta cephalotes Carson 7 Fig. 3 : A. cephalotes nest size vs the average distance traveled in meters for observed foraging sites. This difference was statistically significant (T=2. 83, p=.006).

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Foraging and Nesting Behavior of Atta cephalotes Carson 8 Table 1: List of foraged plant species with corresponding plant family. Also included is the number of individual foraged plants in each species by raw count and by percentage. *A. cephalotes foraged items from the ground at five foraging sites. These items includ ed white flower petals, dead leaves, twigs, and tree bark. Plant Species Plant Family Number of Individual Plants Foraged Proportion of Individual Plants Foraged Asteraceae 1 Asteraceae 3 3.4% Asteraceae 2 Asteraceae 2 2.3% Cana india Cannaceae 1 1.1% Cecropia obtusifolia Urticaceae 3 3.4% Citrus Limon Rutaceae 1 1.1% Conostegia xalapensi s Melastomataceae 8 9.2% Croton niveus Euphorbiaceae 4 4.6% Danopsis Americanus Timeliaceae 1 1.2% Dyphysa Americana Fabaceae 2 2.3% Ficus costarricana Moraceae 2 2.3% Hamelia Patens Rubiaceae 3 3.6% Inga punctata Fabaceae 23 26.4% Malvaviscus arboreus Malvaceae 1 1.1% Mangifera indica Anacardiaceae 1 1.1% Matayba opositifolia Sapindaceae 2 2.3% Meliosma spp. Sabiaceae 2 2.3% Monstera deliciousa Araceae 1 1.1% Myrciantes spp. "black" Myrtaceae 1 1.1% Myrsine coriaceae Myrsinaceae 3 3.4% Stenotaphrum secundatum Poaceae 1 1.1% Syzygium jambos Myrtaceae 2 2.3% Tecoma stans Bignoniaceae 2 2.3% Trema micrantha Cannabaceae 6 6.9% Zanthoxylum Fagara Rutaceae 7 8.0% Other* Ground Items* 5 5.7% Total 87 100%

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Foraging and Nesting Behavior of Atta cephalotes Carson 9 Table 2: Ecosystems, locations, and nest densities of six studies, including my own. Carson, 2019 Meyer, et al. 2009 Vas concelos et al. 1995 Jaffe, Vilela, 1989 Wirth et al. 2007 Perfecto et al. 1993 Location La Calandria Forest, Costa Rica Coimbra, Brazil Fazendas Dimona, Brazil Orinoco Amazon Basin Coimbra, Brazil Puerto Viejo, Costa Rica Ecosystem Secondary Tropical Rainforest Atlantic Lower Montane Rain Forest Primary Tropical Evergreen Forest Primary Tropical Rainforest Atlantic Lower Montane Rain Forest Primary Tropical Rain Forest, Caribbean Lowlands Nest Density in Nests/ha 1.55 2.43.6 near mono culture 0.20.34 in primary forest 0.03 0.045 0.33 in primary forest, 2.79 near monoculture 0.50.71

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Foraging and Nesting Behavior of Atta cephalotes Carson 10 Table 3: Location, ecosystem, proportion of plant species foraged, mutual foraged plants, and preferred plant species for three forage behavior studies, including my own. Carson, 2019 Blanton and Ewel, 1985 Cherret, 1968 Location La Calandria Forest, Costa Rica Tue rialba, Costa Rica Bartica, Guyana Ecosystem Secondary Tropical Rainforest Tropical Premontane Wet Forest Wallaba Forest, Tropical Rain Forest Number of Foraged Plant Species/Total Plant Species A vailable 23/NA 17/332 36/72 Mutual Foraged P lants with Carson, 2019 NA T. micrantha, C. obtusifolia, and Croton spp. N one Preferred Plant Species Foraged Inga Punctata Manihot esculenta Terminalia amazonica and Eschweilera corrugate

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Foraging and Nesting Behavior of Atta cephalotes Carson 11 D ISCUSSION Nest Location There are a few possible explanations why A. cephalotes prefer to build nests in open areas and forest edges. One le ading theory is that A. cephalotes build more nests in these areas due to a greater abundance of pioneer plant species (Silva et al. 2013). A. cephalotes find pioneer plant species more desirable to forage because they tend to lack chemical defenses and have favorable nutri tional content ( Coley, 1983). It’s also possible there are more nests on forest edges and clearings because A. ceph alotes queens attempt to build nests in open areas more often than covered forest. A. cephalotes queens are clumsy flyer s (Jack Longi no, pers. comm.). It is possible they avoid flying through dense canopies, and as a result, are more likely to land in an open clearing to build their nest. Colonies avoided the foraging sites and paths of other leafcutter colonies, which could be a byproduct of their territorial behavior (Salzemann and Jaffe, 1990). A. cephalotes contain a territorial phe r omone that is colonyspecific (Jaffe et al ., 1979), and w hen different ant colonies infringe on each other’s territo ry they can react violently (Carlin and Hlldobler 1986, and Salzemann et al. . 1992 ) . A. cephalotes may be avoiding the pheromone trails from different A. cephalotes colonies , hence the lack of overlapping trails and lack of shared forage sites between the different colonies. Nest Density The plots of young secondary forest, clearing near the field station, and prominent forest edge near the field station likely contribute to t he high nest density of La Calandria . La Calandria holds a nest density greater than values commonly found for primary tropical rainforest, suggesting La Calandria may need more time to recover unti l its nest density resembles that of a healthy primary forest. However, it is encouraging to se e that this forest segment holds a lower nest density than the nest densities found in agriculture areas, suggesting the reforestation project at La Calandria has made reasonable progress. It’s important to consider the ecological consequences an increased presence of A. cephalotes could have on a tropical forest ecosystem. Maybe an increased population of leaf cutter ants leads to an increase in its predator populations, such as Nomamyrex esenbeckli , an army ant (Swartz 1998). T he biodiversity and abundance of understory plants decreases near A. cephalotes nests ( Garrettson et al. 1998) . Additionally, these leafcutter ants can reduce nutrient availability for plants by removing leaf litter near their nest (Meyer et al., 2013) . A. cephalotes also forage heavily from seedlings that are close to their nest (Meyer et al . 2010). Some or all of these ecological effects could become more prominent in secondary forest s with elevated nest densities, such as La Calandria. Foraging Behavior: Plant Species The foraged plant species composition at La Calandria differs significantly than the fora ged plant species composition of other ecosystems, highlighting these creatures ’ ability to

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Foraging and Nesting Behavior of Atta cephalotes Carson 12 f orage from a variety of plant species. Blanton and Ewel (1985) studied foraging behavior of A. cephalotes on the C aribbean slope of Costa Rica at a lower elevation than La Calandria, which likely explains why the ir foraged plant composit ion differed significantly to my study. The capability for A. cephalotes to forage from a variety of plant species may allow them to easily adapt to changing plant distribution s and biodiversity due to climate change (Randin et al. 2009) . There are a few possible explanations for why I. punctata, C .a xalapensis, and Z .fagara comprised nearly half of the observed foraged plants in La Ca landria. One possible theory is these plant species existed in greater abundance than other plant species of La Calandria. I did not record biodiversity data, so I cannot confirm nor deny this notion. It’s also possible A. cephalotes preferred to forage from these three plants because they lacked plant defenses. I. punctata produces nectar from its extrafloral nectaries to attract ants to itself, which then defend the plant from potential herbivores. However, this mutualism is less eff ective at higher elevations, likely due to a reduced abundance of these mutualistic ants at higher elevations ( Koptur, 1985). Researchers observed that Azteca instabilis, an Azteca ant, defended C. xalapensis against flea beetles ( Gonthier et al. 2010). La Calandria rests at 1250m, while A. instabilis do not typically reside above elevations of 500m Longino, 2007), so they could not have been present at La Calandria. Marr and Tang (1992) observed that other plants of the Zanthoxylum genus contained pesticid al chemicals in their leaves. However, it’s unclear if this is also holds true specifically for Z. fagara. Foraging Behavior: Foraging distance On average, l arger A. cephalotes nests traveled 15m farther than smaller nests to forage from plants. One possible explanation for this result is that smaller n ests do not have enough ants to ma intain a pheromone trail over long distance s . The pheromone s that leafcutter ants leave e vaporate rather quickly (Riley et al. 1974) . At longer distances, it’s possible that smaller colonies may not have enough ants to generate pheromone trails faster than their rate of evaporation. Another possible theory is that smaller ant colonies don’t have enough ants to clear trails over longer distances. Worker ants have a variety of tasks, and some of them are dedicated to clearing debris from foraging trails ( Howard 2001) . Smaller ant colonies may not have enough workers to simultaneously a ) maintain and clear a long foraging trail and b) travel long distances to forage from plants. Conclusion The nest density of La Calandria suggests that this reforestation project has made progress, but needs more time until its nest density resembles that of a primary forest . The nesting patterns of A. cephalotes confirmed that these leafcutter ants tend to build nests on clearings and the forest edge , but also provided further evidence of their territorial behavior . Additionally, A. cephalotes exhibit an extensive pa l let when foraging from plants , wh ich may allow them to adapt well to altering plant biodiversity and distributions.

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Foraging and Nesting Behavior of Atta cephalotes Carson 13 A CKNOWLEDGEMENTS The first person I would like to thank for their help would be my advisor and mentor Emilia Triana. Her experience and knowledge of leafcutter ants proved incredibly useful as I designed and carried out my experiment. I would also like to thank Randy Chinchilla from the Monteverde Institute, who created the nest map and calculated foraging distances using the GPS data that I recorded. Last but not lea st I would like to thank Eladio Cruz, who identified the plants that the leaf cutter ants foraged . These three people are a huge reason why my research project was as successful as it was. LITERATURE CITED Berish, Cory W. “Leaf Cutting Ants (Atta Cephalot es) Select Nitrogen Rich Forage.” American Midland Naturalist , vol. 115, no. 2, 1986, p. 268., Blanton, Chantal M., and John J. Ewel. “Leaf Cutting Ant Herbivory in Successional and Agricultural Tropical Ecosystems.” Ecology , vol. 66, no. 3, 1985, pp. 861–869., \ Carlin, Norman F., and Bert Hlldobler. "The kin recognition system of carpenter ants (Camponotus spp.)." Behavioral Ecology and Sociobiology 19.2 (1986): 123134. Cherrett, J. M. “The Foraging Behavior of Atta Cephalotes L. (Hymenoptera, Formicidae).”The Journal of Animal Ecology , vol. 37, no. 2, 1968, p. 387., Coley, Phyllis D. "Herbivory and defensive characteristics of tree species in a lowland tropical forest." Ecological monographs 53.2 (1983): 209 234. Dennis Leston, A Neotropical Ant Mosaic, Annals of the Entomological Society of America , Volume 71, Issue 4, 17 July 1978, Pages 649–653, Garrettson, Mariana, et al. “Diversity and Abundance of Understory Plants on Active and Abandoned Nests of Leaf Cut ting Ants (Atta Cephalotes) in a Costa Rican Rain Forest.” Journal of Tropical Ecology , vol. 14, no. 01, 1998, pp. 17–26., \ Hlldobler, Bert, and Edward O. Wilson. The Ants . Springer Vlg, 1990. Howard, Jerome J. "Costs of trail construction and maintenance in the leaf cutting ant Atta columbica." Behavioral Ecology and Sociobiology 49.5 (2001): 348356. Jaffe, K. "Control of Atta and Acromyrmex spp. in pine tree plantations in the Venezuelan llanos." (1986). Jaffe, K., M. Bazire Benazet, and P. E. Howse. "An integumentary pheromone secreting gland in Atta sp: Territorial marking with a colonyspecific pheromone in Atta cephalotes." Journal of Insect Physiology 25.10 (1979): 833839. Jaffe, Klaus, and Evaldo Vilela. “On Nest Densities of the Leaf Cutting Ant Atta Cephalotes in Tropical Primary Forest.” Biotropica , vol. 21, no. 3, 1989, pp. 234–236. JSTOR , Koptur, Suzanne. "Alternative defenses against herbivores in Inga (Fabaceae: M imosoideae) over an elevational gradient." Ecology 66.5 (1985): 16391650. Lewis, T., et al. “Rhythmic Foraging in the Leaf Cutting Ant Atta Cephalotes (L.) (Formicidae: Attini).” The Journal of Animal Ecology , vol. 43, no. 1, 1974, p. 129., Longino, John Thomas. A taxonomic review of the genus Azteca (Hymenoptera: Formicidae) in Costa Rica and a global revision of the aurita group. Longwood, FL: Magnolia Press, 2007. Marr, K. L., and C. S. Tang. "Volatile insecticidal compounds and chemical variabil ity of Hawaiian Zanthoxylum (Rutaceae) species." Biochemical systematics and ecology 20.3 (1992): 209 217.

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Foraging and Nesting Behavior of Atta cephalotes Carson 14 Meyer, Sebastian T., et al. “Ecosystem Engineering by Leaf Cutting Ants: Nests of Atta Cephalotes Drastically Alter Forest Structure and Microclimate.” Ecological Entomology , John Wiley & Sons, Ltd (10.1111), 15 Nov. 2010, Meyer, Sebastian T., et al. “Persisting Hyper Abundance of Leaf Cutting Ants (Attaspp.) at the Edge of an Old Atlanti c Forest Fragment.” Biotropica, vol. 41, no. 6, 2009, pp. 711–716., Meyer, Sebastian T., et al. "Performance and fate of tree seedlings on and around nests of the leaf cutting ant Atta cephalotes: Ecological filters in a fragmented forest." Austral ecology 36.7 (2011): 779 790. Meyer, Sebastian T., et al. "Leaf cutting ants as ecosystem engineers: topsoil and litter perturbations around Atta cephalotes nests reduce nutrient availability." Ecological Entomology 38.5 (2013): 497504. Nichols Orians, Colin M., and Jack C. Schultz. "Leaf toughness affects leaf harvesting by the leaf cutter ant, Atta cephalotes ( L.) ( Hymenoptera: Formicidae)." Biotropica (1989): 8083. Perfecto, Ivette, and John Vandermeer. "Distribution and turnover ra te of a population of Atta cephalotes in a tropical rain forest in Costa Rica." Biotropica (1993): 316321. Randin, Christophe F., et al. "Climate change and plant distribution: local models predict highelevation persistence." Global Change Biology 15.6 (2009): 15571569. Riley, R. G., et al. "Methyl 4methylpyrrole 2carboxylate: a volatile trail pheromone from the leaf cutting ant, Atta cephalotes." Journal of insect physiology 20.4 (1974): 651654. Salzemann, A., and K. Jaffe. "On the territorial behavior of field colonies of the leaf cutting ant Atta laevigata (Hymenoptera: Myrmicinae)." Journal of Insect Physiology 36.2 (1990): 133138. Salzemann, A., et al. "Leaf cutting ant Atta laevigata (Formicidae: Attini) marks its territory with colonyspecific Dufour gland secretion." Journal of chemical ecology 18.2 (1992): 183 196. Silva, Paulo Svio Damsio, et al. "Foraging in highly dynamic environments: leaf cutting ants adjust foraging trail networks to pioneer plant availability." Entomologia Experimentalis et Applicata 147.2 (2013): 110119. Swartz, Monica B. "Predation on an Atta cephalotes colony by an army ant Nomamyrmex esenbecki." Biotropica 30.4 (1998): 682684. Vasconcelos, Heraldo L., and J. Malcolm Cherrett. "Changes in leaf cutting ant populations (Formicidae: Attini) after the clearing of mature forest in Brazilian Amazonia." Studies on Neotropical Fauna and Environment 30.2 (1995): 107113. Wirth, Rainer, et al. “Increasing Densities of Leaf Cutting Ants (Atta Spp.) with Proximity to the Edge in a Brazilian Atlantic Forest.” Journal of Tropical Ecology , vol. 23, no. 4, 2007, pp. 501–505.,


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