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Made available in DSpace on 2022-04-29T08:35:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-12-01 Claustral foundation of nests by Atta sexdens Forel (Hymenoptera: Formicidae) involves great effort by its queens, solely responsible for the cultivation of the fungus and care for her offspring at this stage. The minimum workers, after 4 months, open access to the external environment to foraging plants to cultivate the symbiotic fungus, which decomposes the plant fragments and produces gongilidea nodules as food for the individuals in the colony. Colony gas exchange and decomposition of organic matter in underground ant nests generate carbon dioxide (CO2) emitted into the atmosphere. We described the carbon dioxide concentration in colonies in the field. The objective was to evaluate the carbon dioxide concentration in initial A. sexdens colonies, in the field, and their development. The CO2 level was also measured in 4-month-old colonies in the field, using an open respirometric system fitted with an atmospheric air inlet. The CO2 level of the respirometric container was read by introducing a tube into the nest inlet hole and the air sucked by a peristaltic pump into the CO2 meter box. The CO2 concentration in the initial colony was also measured after 4 months of age, when the offspring production (number of eggs, larvae, pupae and adult workers) stabilized. Ten perforations (15 cm deep) was carried out in the adjacent soil, without a nest of ants nearby, to determine the concentration of CO2. The composition of the nests in the field was evaluated after excavating them using a gardening shovel and they were stored in 250 ml pots with 1 cm of moistened plaster at the bottom. The CO2 concentration was higher in field nest than in adjacent soil. The concentration of carbon dioxide in A. sexdens nests in the field is higher than in those in the soil, due to the production of CO2 by the fungus garden and colony. Departamento de Proteção Vegetal Universidade Estadual Paulista (UNESP) Faculdade de Ciências Agronômicas Campus Experimental de Itapeva Universidade Estadual Paulista Departamento de Entomologia/BIOAGRO Universidade Federal de Viçosa Laboratório de Fitossanidade (FitLab) Instituto Federal de Mato Grosso Departamento de Proteção Vegetal Universidade Estadual Paulista (UNESP) Faculdade de Ciências Agronômicas Campus Experimental de Itapeva Universidade Estadual Paulista

Made available in DSpace on 2021-06-25T12:30:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-12-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Leaf-cutting ants are widely distributed in Brazil, particularly species of the genus Atta. We therefore described the occurrence of leaf-cutting and grass-cutting ant species of the genus Atta. Five routes comprising some of the main highways in the South, Southeast, Midwest, and North of Brazil were sampled, in addition to ants received from other 82 municipalities, composing 300 municipalities sampled. This is the first comprehensive study of Atta in Brazil. The following species and subespecies were found: A. laevigata, A. capiguara, A. sexdens rubropilosa, A. sexdens piriventris, A. sexdens sexdens, and A. cephalotes. Atta laevigata and A. capiguara were the species present in the largest number of the Brazilian municipalities sampled. Atta sexdens piriventris was only recorded in the southern region of Brazil. Atta bisphaerica presented lower expansion than A. capiguara. Atta cephalotes and Atta opaciceps are species of very restricted occurrence. Southeastern region was characterized by the occurrence of A. capiguara and A. laevigata. Atta laevigata exhibited a generalized pattern of occurrence in the Midwest and North. Our study contributes to a better understanding of the so far unknown occurrence of leaf-cutting and grass-cutting ants within Brazil. State Univ Sao Paulo, Sch Agr Sci, Vegetal Protect Dept, Lab Social Insects Pests, Botucatu, SP, Brazil State Univ Northern Parana, Vegetal Prod Dept, Campus Luiz Meneghel, Bandeirantes, Brazil State Univ Southwestern Bahia, Dept Crop Sci & Anim Sci, Vitoria Da Conquista, Brazil State Univ Sao Paulo, Sch Agr Sci, Vegetal Protect Dept, Lab Social Insects Pests, Botucatu, SP, Brazil CNPq: 301718/2013-0

Made available in DSpace on 2020-12-10T17:33:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-05-22 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Colonies of leaf-cutting ants of the genus Atta need to collect large quantities of vegetal substrate in their environment to ensure their growth. They do so by building and extending over time a foraging network that consists of several underground tunnels extending above ground by physical trails. This paper presents a longitudinal study of the foraging network of two mature colonies of the grass-cutting ant Atta capiguara (Goncalves) located in a pasture in central Brazil. Specifically, we investigated whether the extension of the foraging area of the colonies required to reach new resources occurs by building new and longer underground tunnels or by building new and longer physical trails. Each nest was surveyed at intervals of approximately 15 days during 1 year. At each survey we mapped the position of the tunnel entrances and foraging trails at which activity was observed. In addition, we assessed the excavation effort of the colonies since the last survey by the number and distance to the nest of new tunnel entrances, and the physical trail construction effort by the number and length of newly built physical trails. Our study reveals that in A. capiguara the collection of new resources around the nest required to ensure the continuous growth of the colonies is achieved mainly through the excavation of new underground tunnels, opening at greater distance from the nest, not through the building of longer aboveground physical trails. Univ Estadual Paulista, Sao Paulo, Brazil Univ Fed Juiz de Fora, Juiz De Fora, Brazil Univ Toulouse, CNRS, Toulouse, France Univ Estadual Paulista, Sao Paulo, Brazil FAPESP: 2011/003699 CAPES: 633/08

Made available in DSpace on 2018-12-11T17:34:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Atta bisphaerica is a species of grass-cutting ants commonly found in the Cerrado biome. The Brazilian Cerrado (savanna) biome covers 2 million km representing 23% of the area of the country. It is an ancient biome with rich biodiversity, estimated at 160,000 species of plants, fungi and animals. However, little is known about their nest architecture development. This study investigated the architecture of fourteen A. bisphaerica nests from Botucatu, São Paulo, Brazil. Molds were made of the nests by filling them with cement to allow better visualization of internal structures such as chambers and tunnels. After excavation, the depth and dimensions (length, width, and height) of the chambers were measured. As expected, there was a lateral development in the nests and increase in the number of chambers over time. Results showed that in nests with an estimated age of 14 months, the average depth was 1.6 ± 0.4 m; for those with 18 months it was 2.2 ± 0.7 m and at 28 months it was 2.5 ± 0.7 m. The number of chambers varied from 4 to 7 in 28-month nests, 2 to 4 in 18-month nests, and from 2 to 3 in 14-month nests. With respect to the dimensions of the internal tunnels, there were variations in their average width, increasing with time. The fungus chambers were located beneath the largest mound of loose soil. This study contributes to a better understanding of the so far unknown nest architecture development of A. bisphaerica grass-cutting ants. Universidade Estadual Paulista (UNESP) Faculdade de Ciências Agronômicas Universidade Estadual do Sudoeste da Bahia (UESB) Departamento de Fitotecnia e Zootecnia Laboratório s de Entomologia Universidade Estadual Paulista (UNESP) Faculdade de Ciências Agronômicas CNPq: 301718/2013-0

Made available in DSpace on 2021-06-25T12:20:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01. Added 1 bitstream(s) on 2021-07-15T14:36:13Z : No. of bitstreams: 1 S0085-56262020000300206.pdf: 1039700 bytes, checksum: b072abef0afea0c5f47e704564172bcc (MD5) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Atta capiguara grass-cutting ants are commonly found in the Cerrado biome, in open fields. Although grass-cutting ants build giant nests, little has been elucidated about this building pattern and when chambers and tunnels emerge. The present study describes the nest architecture development of A. capiguara grass-cutting ants from data on 31 cement-molded nests. A. capiguara nests grow with increases in the number of fungus chambers and emergence and increase of waste chambers and foraging tunnels. The structural growth of A. capiguara nests in the first year and a half of age (18 months) is vertical, with the building of the first chambers in the soil profile. After 18 months, the nests grow sideways with the addition of chambers and tunnels, and the first waste chambers appear. Between 18 and 54 months, the number of fungus chambers increases from 1-3 to 21-32, and the chambers are concentrated at the soil surface, although they can be found more than 3 in deep. In addition, the total volume of the waste chambers increases with the increment in the fungus chambers volume. Thus, this study contributes to understanding the nest architecture development of A. capiguara grass-cutting ants and demonstrates that the total volume of waste chambers is proportional to the total volume of fungus chambers suitable for the colony. Univ Estadual Paulista, Fac Ciencias Agronom, Dept Protecao Vegetal, Botucatu, SP, Brazil Univ Estadual Paulista, Fac Ciencias Agronom, Dept Protecao Vegetal, Botucatu, SP, Brazil CAPES: 001 CNPq: 301-938/2017-2

Made available in DSpace on 2019-10-06T16:30:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-04-03 The success of incipient colonies of leaf-cutter ants depends on multiple factors such as temperature, humidity, soil type, the queen’s fertility and vigor, frequency of harmful microfungi, among others. Based on this observation, three factors related to Atta sexdens were characterized: (1) initial nest morphology (depth and volume); (2) queen oviposition rate; and (3) prevalence of Escovopsis (parasitic fungus) and other fungi in incipient colonies. Our observation showed a variation in chamber dimensions and volume, indicating differences in colony development rates. The oviposition rate of queens from nests of the same age showed a difference among queens. About microfungi prevalence, it was found that many are potentially deleterious. In particular, the parasite Escovopsis was present in 16.7% of the colonies. Our study shows positive correlations between queen condition and nest size/fungus garden size. These correlations collectively suggest that ecological factors such as plant availability can generate substantial variation between nests and thus shape the success of incipient colonies. Laboratory of Entomology Department of Phytotechny and Zootechny State University of Southwestern Bahia [Universidade Estadual do Sudoeste da Bahia] (UESB) Laboratory of Social Insects-Pests Department of Vegetal Protection School of Agricultural Sciences São Paulo State University [Universidade Estadual Paulista] (UNESP), Postal Code 237 Laboratory of Agricultural Entomology Agronomy Department College of Agricultural Sciences University of Western São Paulo [Universidade do Oeste Paulista] (UNOESTE) Laboratory of Social Insects-Pests Department of Vegetal Protection School of Agricultural Sciences São Paulo State University [Universidade Estadual Paulista] (UNESP), Postal Code 237

Made available in DSpace on 2020-12-10T19:50:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-02-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Toxic baits are the most efficient method to control leaf-cutter ants in eucalyptus forests for paper and cellulose production. For the proper use of these baits, insecticide compounds must reach workers and contaminate them. Thus, understanding how these baits are processed inside the nests is vital for a successful control, especially when it comes to genus Acromyrmex. Lack of information on toxic baits and on contamination of Acromyrmex workers raises the question: do workers from subspecies Acromyrmex subterraneus (Forel) prepare leaves and toxic baits in similar ways for their fungus garden? To answer it, this study described and analyzed the behavioral repertoire executed by A. subterraneus workers during the preparation of leaf disks and baits and their incorporation into the fungus garden. Results show that the act of licking the substrate was the most frequently executed behavior, regardless of subspecies or size categories. Moreover, additional behaviors have been observed when workers processed the baits, such as licking and scraping their jaws on the surface of the bait pellet, as well as licking and biting fragments of bait pellets, moistening them. Thus, it is concluded that the preparation of baits is different from that of leaves; baits are more processed and can therefore contribute to contaminating workers via insecticides. Sao Paulo State Univ, Sch Agr Sciences,Vegetal Protect Dept, Lab Social Insects,Pests, Botucatu, SP, Brazil Sao Paulo State Univ, Expt Campus Itapeva, Sao Paulo, SP, Brazil Univ w Sao Paulo, Coll Agr Sciences, Agron Dept, Lab Agr Entomol, Presidente Prudente, SP, Brazil Sao Paulo State Univ, Sch Agr Sciences,Vegetal Protect Dept, Lab Social Insects,Pests, Botucatu, SP, Brazil Sao Paulo State Univ, Expt Campus Itapeva, Sao Paulo, SP, Brazil CNPq: . 301167/2003-6 CAPES: Finance Code 001

Made available in DSpace on 2020-12-10T19:40:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-11-07 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Leaf-cutter ants perform a series of specialized behaviors in preparing plant substrates for their symbiotic fungus. This process may be related to contamination of workers by substances such as insecticides, leading us to hypothesize that substances are spread among workers through behaviors they perform to grow the fungus. To test this hypothesis, we analyzed the behavioral acts of workers during the processing of the pellets by using a fat-soluble tracing dye, since the active ingredient that composes toxic baits, used for control of leaf-cutter ants, is fat-soluble. The frequencies of performed behaviors were recorded and the number of dyed workers was assessed after fungus cultivation. The most frequent behavior is allogrooming and corresponds to 45.87% of the contamination process in workers, followed by holding, licking, and cutting pellets, which account for 40.22% of the process. After pellet processing, the workers had their external and internal morphological structures marked by the tracing dye-93.75% and 79.25%, respectively. These results confirm that behaviors performed during fungus cultivation contribute to dispersing substances such as insecticides, causing the contamination of workers. Univ Estadual Paulista, Fac Ciencias Agron, Dept Protecao Vegetal, Botucatu, SP, Brazil Univ Fed Piaui, Campus Univ Ministro Petronio Portella, Teresina, PI, Brazil Univ Estadual Paulista, Fac Ciencias Agron, Dept Protecao Vegetal, Botucatu, SP, Brazil CAPES: 001 CNPq: 301-938/2017-2

Made available in DSpace on 2019-10-06T16:16:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-12-25 Research related to the comparative biology of phylogenetically close ant species has received little attention, although it is the basis for understanding the systematics of some sibling groups. The objective was to study the polygyny, oviposition, life cycle and longevity of the three subspecies of leaf-cutting ants. For that, we studied: oviposition rate – queens from three colonies were individually placed in plastic containers, and at 24-hour intervals, the laid eggs were quantified over a period of 96 hours; the workers’ life cycle – the development of immature ants was observed every 24 hours and, as a result, the duration of each stage of development was determined; the workers’ longevity – newly emerged adults were tagged and returned to the fungus chamber of their respective nests, and daily observations were made in each of the nest’s chamber. Laying rates were variable in the three queens studied, with a mean of total eggs laid of 271 for Acromyrmex subterraneus brunneus, 113 for Acromyrmex subterraneus subterraneus and 119 for Acromyrmex subterraneus molestans.The incubation period was 21.2 days in A. s. brunneus, 22.8 days in A. s. subterraneus and 20.4 days in A. s. molestans. The larval phase and pupal phase lasted on average 22.5 and 21.2 days in A. s. brunneus, 22.8 and 15.8 days in A. s. subterraneus and 17.2 and 14.2 days in A. s. molestans, respectively. Life cycle was different in the studied taxa, from 62 to 77 days in A. s. brunneus, from 59–68 days in A. s. subterraneus and from 51 to 55 days in A. s. molestans. The workers’ longevity varied between subspecies A. s. brunneus, A. s. subterraneus and A. s. molestans. Laboratory of Social Insects-Pests Vegetal Protection Department College of Agricultural Sciences São Paulo State University (Universidade Estadual Paulista) UNESP Laboratory of Agricultural Entomology Agronomy Department College of Agricultural Sciences University of Western São Paulo (Universidade do Oeste Paulista) (UNOESTE) College of Biological Sciences Student Federal University of Piauí Laboratory of Social Insects-Pests Vegetal Protection Department College of Agricultural Sciences São Paulo State University (Universidade Estadual Paulista) UNESP

Cyphoderus innominatus Mills, 1938 (Collembola: Paronellidae) was first observed in early colonies of Atta sexdens leaf-cutting ants (Hymenoptera: Formicidae). The colonies were collected on February 6, 2019, from a transition area between the Atlantic Forest and the Cerrado, located in the municipality of Botucatu, São Paulo, Brazil. A total of four colonies collected had an average population density of 227 ± 212 C. innominatus individuals, and most of the latter were found in peripheral areas inside the fungus-garden-growing chamber of the colony. In addition, we observed a possible defensive behavior on the part of workers when C. innominatus individuals were present in the fungus garden chamber. Thus, this is the first record of C. innominatus living in association with early colonies of A. sexdens. Cyphoderus innominatus Mills, 1938 (Collembola: Paronellidae) foi observado pela primeira vez nas primeiras colônias de formigas cortadeiras Atta sexdens rubropilosa , Forel, 1908 (Hymenoptera: Formicidae). Essas colônias foram coletadas em 6 de fevereiro de 2019, em uma área de transição entre a Mata Atlântica e o Cerrado, localizada no município de Botucatu, São Paulo, Brasil. Um total de quatro colônias coletadas teve uma densidade populacional média de 227, de C. innominatus , ea maioria dos últimos foram encontrados em áreas periféricas dentro da câmara de cultivo do jardim de fungo da colônia. Além disso, observamos um possível comportamento defensivo por parte dos trabalhadores quandoC. innominatus estava presente presentes na câmara do jardim de fungos. Assim, este é o primeiro registro de C. innominatus vivendo em associação com colônias iniciais de A. sexdens rubropilosa .

Made available in DSpace on 2018-12-11T17:00:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-01-01 Dynamics of the restoration of physical trails in the grass-cutting ant Atta capiguara. Leaf-cutting ants of the genus Atta build long physical trails by cutting the vegetation growing on the soil surface and removing the small objects they find across their path. Little is known on the dynamics of trail construction in these ants. How much time do they need to build a trail? To answer this question we selected six trails belonging to two different nests of A. capiguara and removed on each trail a block of soil of 20 cm × 15 cm that included a portion of the physical trail. This block was then replaced by a new block of the same size that was removed in the pasture near the trail and that was uniformly covered by the same type of vegetation as that found on the block of soil that was removed. The time required to restore the trail was then evaluated by the length of the grass blades found along the former location of the trail. The results show that ants rapidly restore the portion of the physical trail that was interrupted, which suggests that they could also do the same after their trails have been recolonized by the vegetation. Laboratório de Insetos Sociais-Praga Departamento de Produção Vegetal Faculdade de Ciências Agronômicas Universidade Estadual Paulista (UNESP) MirmecoLab Programa de Pós-graduação em Ciências Biológicas Comportamento e Biologia Animal Universidade Federal de Juiz de Fora Université Fédérale de Toulouse Midi-Pyrénées UPS Centre de Recherches sur la Cognition Animale CNRS Centre de Recherches sur la Cognition Animale Laboratório de Insetos Sociais-Praga Departamento de Produção Vegetal Faculdade de Ciências Agronômicas Universidade Estadual Paulista (UNESP)

Made available in DSpace on 2021-06-25T21:08:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-11-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Simple Summary Atta bisphaerica grass-cutting ants build giant nests with hundreds or thousands of large chambers. Here, we assessed whether the total volume of fungus chambers and other nest parameters grow at close or similar proportions to worker numbers in the A. bisphaerica colony. The fungus garden biomass, external area, and total fungus chamber volume increased at rates similar to that of worker numbers. The total volume of chambers, and external area increased at a similar proportion to that of the number of workers, probably due to the fungus garden allocation needs of the colony. On the other hand, the number of fungus chambers, number of entrance holes, and nest depth increased more slowly than the number of workers. Thus, this study demonstrates that A. bisphaerica nest development regarding the total volume of chambers is similar to the increase in the number of colony workers. Atta grass-cutting ants (Formicidae: Myrmicinae: Attini) are found in the Cerrado biome and build giant nests with hundreds or thousands of large chambers. We assessed for Atta bisphaerica grass-cutting ants whether the total volume of fungus chambers and other nest parameters grow at close or similar proportions to worker numbers in the colony. Data on fungus garden biomass, population, external area, number of entrance holes, number of fungus chambers, total fungus chambers volume, and nest depth were obtained during colony growth/nest development. Our results reveal that the fungus garden biomass, external area, and total fungus chamber volume increased at rates similar to the increase in the number of workers. The total volume of chambers, and external area increased at a similar proportion to the increase in number of workers, probably due to the fungus garden allocation needs of the colony. The number of fungus chambers, number of entrance holes, and nest depth increased less than 4-fold for every 10-fold increase in the worker number. In addition, the height of the fungus chambers increased as the width increased, a pattern not observed for tunnel height and length, and the chamber volume increased according to worker number. Thus, this study demonstrates for A. bisphaerica that nest development in terms of chamber volume is similar to the increase in number of colony workers, and this contributes to a better understanding of Atta nest architecture. Sao Paulo State Univ, Sch Agron Sci, Dept Vegetal Protect, BR-18603970 Botucatu, SP, Brazil Sao Paulo State Univ, Sch Agron Sci, Dept Vegetal Protect, BR-18603970 Botucatu, SP, Brazil CAPES: 001 CNPq: 301718/2013-0

Our study seeks to discover contamination routes of leaf-cutting worker ants during chemical control by formicide baits. To do so, toxic baits containing fat-soluble tracer dye were provided to colonies of three subspecies of Acromyrmex under laboratory conditions, in order to assess the proportion of dyed workers by size category, as well as dyed internal morphological structures. Results showed that nearly 50% of the workers come into contact with the active ingredient, since the internal structures of their bodies are dyed by the fat-soluble tracer dye within the first 24 h from contact with the toxic bait. In addition, the three subspecies of leaf-cutting ants present a similarity as to the contamination of their workers, probably due to their specialized behavior performed during the growth of the fungus garden with the baits. We conclude that the workers’ pattern of behavior during fungus garden growth was the main means for dispersion of a fat-soluble substance among approximately half of the nest mates in our experiments, serving as a model for further studies on contamination of worker ants with insecticides.

Made available in DSpace on 2018-12-11T17:11:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-06-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Atta capiguara is a grass-cutting ant species frequently found in Cerrado biome. However, little is known about the giant nest architecture of this ant. In this study, we investigated the architecture of three A. capiguara nests from a fragment of Cerrado in Botucatu, São Paulo, Brazil. Casts were made of the nests by filling them with cement to permit better visualization of internal structures such as chambers and tunnels. After excavation, the depth and dimensions (length, width, and height) of the chambers were measured. The results showed the shape of Atta capiguara nests consisting of mounds of loose soil with unique features resembling a conic section. The fungus chambers were found distant from the mound of loose soil and were spaced apart and distributed laterally at the soil profile. The waste chambers were located beneath the largest mound of loose soil. Both the fungus and waste chambers were separated and distant. Our study contributes to a better understanding of the so far unknown nest architecture of the grass-cutting ant A. capiguara. Laboratório de Insetos Sociais-Praga Departamento de Produção Vegetal Faculdade de Ciências Agronômicas/UNESP, Caixa Postal 237 Laboratório de Entomologia Departamento de Fitotecnia e Zootecnia Universidade Estadual do Sudoeste da Bahia (UESB), Caixa Postal 95 Laboratório de Insetos Sociais-Praga Departamento de Produção Vegetal Faculdade de Ciências Agronômicas/UNESP, Caixa Postal 237 FAPESP: 03/00082-5 FAPESP: 03/06935-0 CNPq: 301718/2013-0

Atta capiguara is a grass-cutting ant species frequently found in Cerrado biome. However, little is known about the giant nest architecture of this ant. In this study, we investigated the architecture of three A. capiguara nests from the fragment of cerrado in Botucatu, São Paulo, Brazil. Casts were made of the nests by filling them with cement to permit better visualization of internal structures such as chambers and tunnels. After excavation, the depth and dimensions (length, width, and height) of the chambers were measured. The results showed the typical shape of Atta capiguara nests consisting of mounds of loose soil with unique features resembling a conic section. The fungus chambers were found outside the apparent main part of the nest and were spaced apart and distributed laterally at ground level. The waste chambers were located beneath the largest mound of loose soil. Both the fungus and waste chambers exhibited a sectoral distribution. Our study contributes to a better understanding of the so far unknown nest architecture of the grass-cutting ant A. capiguara.

Made available in DSpace on 2018-11-26T16:48:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-08-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) French Ministry of Education The objective of this study was to investigate the seasonal change in the pattern of foraging activity in the leaf-cutting ant Atta capiguara and to provide an estimate of the annual herbivory rate of its colonies. We surveyed at least once a month during 12 months, the foraging activity of two colonies located in a pasture of central Brazil. Each survey consisted in counting the number of ants exiting and returning (laden or unladen) to their nests during 10 min every hour during 24 h. The air temperature and relative humidity were noted at the beginning of each survey. Independent of the season, the colonies presented two peaks of foraging activity, one small peak at the beginning of the day and another peak at the end of the day. During the dry season, the diurnal activity ceased almost completely between 10:00 and 16:00. The proportion of ants returning to the nest laden with a leaf fragment was also lower than during the humid season. Activity rhythm depended significantly on both air temperature and humidity: foraging activity peaked when the temperature was around 25 A degrees C and relative humidity around 66 %. Based on the statistical model used to describe the activity rhythm, we estimated that over a period of 1 year, the total dry biomass of vegetation collected by the two colonies studied was, respectively, 25.16 kg for the bigger nest, and 11.69 kg for the smaller one, or an equivalent of 104.83-kg and 48.71-kg fresh biomass, respectively. Univ Estadual Paulista, Fac Ciencias Agron, Dept Protecao Vegetal, POB 237, BR-18610307 Botucatu, SP, Brazil Univ Fed Juiz de Fora, Inst Ciencias Biol, Campus Univ Martelos, BR-36036330 Juiz De Fora, MG, Brazil Univ Toulouse, CNRS, UPS, Ctr Rech Cognit Anim,Ctr Biol Integrat, 118 Route Narbonne, F-31062 Toulouse 9, France Univ Estadual Paulista, Fac Ciencias Agron, Dept Protecao Vegetal, POB 237, BR-18610307 Botucatu, SP, Brazil FAPESP: 2011/003699 CAPES: 633/08

Made available in DSpace on 2018-12-11T17:02:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-07-10 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) ABSTRACT: Acromyrmex balzani is a grass-cutting ant species frequently found in Cerrado areas. However, little is known about the architecture of the polydomous nests of this ant. Fifteen A. balzani nests located in a cerrado region in Botucatu, São Paulo, Brazil, were studied. The polydomous nests were studied in three ways. First, we investigated the architecture in nests moulded with cement and without moulding. Second, we performed an aggressiveness test among workers in different subnests and nests. Third, we excavated the nest and collected the colony to measure the population, verifying the existence or not of a queen in all nests. A cement mould was made of seven nests to permit better visualization of internal structures such as chambers and tunnels. Eight nests were excavated without moulding and white neutral talc was used to highlight the parts of the nests. After excavation, the depth and dimensions (length, width and height) of the chambers were measured. The results showed that the nests had a single entrance hole whose structure consisted of straw and other plant residues in winter. Mounds of loose soil, if present, were found 6–48 cm from the hole. The number of chambers containing fungus ranged from one to five, with the first being found a few centimetres beneath the ground surface (4 cm) and the last up to a maximum depth of 160 cm. The length of the tunnels ranged from 12 to 28 cm. These tunnels were built in a vertical or inclined position, leading to the chambers. No waste chambers were found, with the waste being deposited externally. Additionally, the polydomous nests contained one to eight subnests. In the aggressiveness test, when concolonial workers were confronted, no aggressiveness was observed. In contrast, when allocolonial workers were confronted, there was a high incidence of aggression among them. Excavation of polydomous nests showed only one queen for each polydomous nest, i.e. subnests with a single queen. Our study contributes to a better understanding of the so far unknown nest architecture of the polydomous grass-cutting ant A. balzani. Laboratório de Insetos Sociais-Praga Departamento de Produção Vegetal Faculdade de Ciências Agronômicas/UNESP Mirmecolab Instituto de Ciências Biologicas Universidade Federal de Juiz de Fora Laboratório de Insetos Sociais-Praga Departamento de Produção Vegetal Faculdade de Ciências Agronômicas/UNESP FAPESP: 07/04010-0 FAPESP: 07/07091-0

Atta laevigata and Atta capiguara are two species of leaf-cutting ants that are found in the pastures of Central Brazil and build huge underground nests linked to the outdoor environment by underground tunnels, which can reach several tens of meters and further extend through foraging trails to distant foraging grounds. The tunnels built by mature colonies of A. capiguara are usually longer and deeper than those built by mature colonies of A. laevigata. The physical trails are also shorter on average. We hypothesized that these differences could be related to differences in thermotolerance between the two species. To test this we collected ants on foraging trails and placed them individually in waterproof test tubes plunged in a thermostatic bath at 25 °C (control), 37 and 39 °C (test temperatures). The results showed that at both 37 and 39 °C, the survival time of A. laevigata was much more extended than that of A. capiguara. A possible explanation for the longer and deeper underground foraging tunnels, as well as the shorter foraging trails, built by A. capiguara may thus be their lower resistance to heat stress. The longer tunnels built by A. capiguara colonies may reduce the exposure to heat of the foraging workers that commute between their nest and the foraging grounds or act as a thermal refuge in which the workers can find temporary protection against high outdoor temperatures.

Made available in DSpace on 2018-12-11T17:04:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-06-01 The nest dug by the leaf-cutter ant queen of the genus Atta is a vertical tunnel interconnected to a small chamber which holds its offspring and the symbiotic fungus. The depth of the initial chamber of the Atta sexdens rubropilosa ranges from 10 to 30 cm below the soil surface. With this information, we asked whether the ideal initial nest depth is adapted to favorable conditions for the initial colony. We hypothesized this depth can provide a minimum temperature range with almost constant temperature, leading to the development of symbiotic fungus and brood yet to emerge. To test this hypothesis, laboratory experiments were carried out and the soil temperature was measured at different depths. The colony development at different temperatures was studied in the laboratory and the brood production (number of eggs, larvae, pupae and adults) was measured until the first workers emergency. Additionally, lipid content and the survival of queens at different temperatures were determined. Our results show a suitable temperature range (ranging from 24.82±3.14°C to 24.11±1.30°C) at a depth of 5 to 25 cm from the ground, an ideal brood development at temperatures of 24 and 28 °C, and consequently a reduction in lipid content of the queens at high temperatures, without affecting their survival in the trial period. These results indicate that the depth of the initial chamber excavated by the queen is suitable for the success of the incipient colony. Laboratório de Insetos Sociais-Praga Departamento de Produção Vegetal Faculdade de Ciências Agronômicas/UNESP, Caixa Postal 237 Campus Experimental de Itapeva/UNESP Laboratório de Insetos Sociais-Praga Departamento de Produção Vegetal Faculdade de Ciências Agronômicas/UNESP, Caixa Postal 237 Campus Experimental de Itapeva/UNESP