ABSTRACT Chemical control using toxic baits containing the active ingredient sulfluramid at 0.3% (w/w) is the main method for controlling leaf-cutting ants of the genera Atta and Acromyrmex. However, since 2009, when sulfluramid was included in Annex B of the Stockholm Convention on Persistent Organic Pollutants, there has been an intense search for new methods that are efficient in controlling these insects. Among said new methods, biological control using pathogenic fungi has shown promising results in laboratory conditions. The objective of this study, given the context presented, was to assess the potential of the fungi Beauveria bassiana and Trichoderma harzianum in controlling Atta sexdens. Colonies of A. sexdens were exposed to the fungi by means of formulated baits provided in a foraging chamber, or of suspensions sprayed on the fungus garden, and had their behavioral changes recorded for 21 days. For both formulations, concentrations of 10 and 20% (w/w) of the fungi being studied were used. The results allowed concluding that baits containing 10 and 20% (w/w) of the fungi B. bassiana and T. harzianum were not efficient in controlling colonies of A sexdens. On the other hand, spraying suspensions of 20% (w/w) of B. bassiana and 10% and 20% (w/w) of T. harzianum was efficient and resulted in 100% mortality of the colonies 11, 9 and 7 days after application, respectively. These findings indicate that the fungi B. bassiana and T. harzianum are promising as agents for the control of A. sexdens colonies, when sprayed on the fungus garden, although there are still some challenges as to their use related to the development of technologies for the application of the pathogen.
RESUMO O controle químico com iscas tóxicas contendo o ingrediente ativo sulfluramida a 0,3% (p/p) é o principal método de controle de formigas cortadeiras dos gêneros Atta e Acromyrmex. No entanto, desde 2009, quando a sulfluramida foi incluída no Anexo B da Convenção de Estocolmo sobre Poluentes Orgânicos Persistentes, há uma intensa busca por novos métodos que sejam eficientes no controle desses insetos. Dentre os novos métodos, o controle biológico por fungos patogênicos tem mostrado resultados promissores em condições de laboratório. O objetivo deste estudo, dado o contexto apresentado, foi avaliar o potencial dos fungos Beauveria bassiana e Trichoderma harzianum no controle de Atta sexdens. Colônias de A. sexdens foram expostas aos fungos por meio de iscas formuladas fornecidas em câmara de forrageamento, ou de suspensões pulverizadas no jardim de fungos, e tiveram suas alterações comportamentais registradas durante 21 dias. Para ambas as formulações, foram utilizadas concentrações de 10 e 20% (p/p) dos fungos em estudo. Os resultados permitiram concluir que iscas contendo 10 e 20% (p/p) dos fungos B. bassiana e T. harzianum não foram eficientes no controle de colônias de A. sexdens. Por outro lado, a pulverização de suspensões de 20% (p/p) de B. bassiana e 10% e 20% (p/p) de T. harzianum foi eficiente e resultou em 100% de mortalidade das colônias aos 11, 9 e 7 dias após a aplicação, respectivamente. Esses achados indicam que os fungos B. bassiana e T. harzianum são promissores como agentes de controle de colônias de A. sexdens, quando pulverizados sobre o jardim de fungos, embora ainda existam alguns desafios quanto ao seu uso relacionados ao desenvolvimento de tecnologias para a aplicação do patógeno.
ABSTRACT 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 m 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.
ABSTRACT Leaf-cutting ants are controlled with toxic baits. For the method’s greater efficiency, the baits must be distributed and processed by workers during fungus cultivation. To test hypotheses whether the mode of action of the active ingredients, which blocks the sodium channels and interrupts the production of ATP in the mitochondria, interferes with fragment distribution in nests; the dispersion of pellets fragments during fungus cultivation by workers was assessed, spatially referencing the fragment onto the fungus garden. Pellets fragments were randomly distributed, but the amount pellets fragments was influenced by the way that the active ingredient acts in the colony.
ABSTRACT Leaf-cutting ants live symbiotically with a fungus that they cultivate on the plant leaves that they cut. The innumerous studies on the plant selection mechanism used by leaf-cutting ants show the researchers’ interest in this issue. Many classical studies propose that plants are selected according to the fungus garden nutritional needs and the absence of potentially harmful substances. This hypothesis is corroborated by behavioral experiments using cycloheximide (fungicide) with citric pulp or forage plants greatly accepted by leaf-cutting ants. According to this hypothesis, under the action of a fungicide, the fungus emits an allomone that informs worker ants that some food is inadequate to its growth. Although some authors state that the cycloheximide “fungicide” used is specific and non toxic to ants, our findings are distinct. In our study, various concentrations of cycloheximide were administered orally to leaf-cutting worker ants in a citric pulp paste diet. After the ingestion period, the ants were isolated and offered the symbiotic fungus for 21 days and the mortality rate was evaluated. As expected, the treatment with 0.01% cycloheximide showed a low mortality rate (8.86%). At 0.1%, the mortality rate was mild (27.85%), and treatment with 1% cycloheximide resulted in moderate mortality (45.57%). In contrast, the positive control with 0.1% sulfluramid showed a high mortality rate (91.14%). Therefore, we concluded that the ingestion of high concentrations of cycloheximide results in a moderate mortality rate in leaf-cutting worker ants.
ABSTRACT 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.
ABSTRACT: Atta sexdens rubropilosa (leaf-cutter ants) has a symbiotic association with a fungus and has a negative interaction with other fungi due to parasitism of the fungus cultivated by ants; also, there are several other fungi with no exact known role occurring in their cultivated fungus garden. In the present study, we use the ITS region (internal transcribed spacer) to identify fungi in colonies treated with toxic baits. Experiments using two toxic baits were carried out: 0.75g of sulfluramid [0.3%] and 0.75g fipronil [0.003%]. Samples of fungi were collected and cultured in Czapek medium for seven days to allow fungal growth and subsequent identification. Total DNA was isolated from 100-150 mg of mycelium using the CTAB method and using PCR, with the universal primers (ITS4 and ITS5), to amplify the ITS region. Sequencing was performed using the Sanger method. Sequences were subjected to BLAST, allowing the identification of nine different species of the orders Agaricales, Eurotiales, Hypocreales, Pleosporales, Saccharomycetales and Tremellales showing a variation in identity of 96-100%. Using “The Automatic Barcode Gap Discovery” analysis, nine groups were identified, corresponding to species described in NCBI. The K2P distances were used to generate a tree using Neighbour-joining, demonstrating that the species were grouped according to phylogenetic groups. We concluded that leaf-cutter ant colonies exhibited a wide variety of fungi and this study suggested that there is no correlation between the species of fungi isolated with the control method used on the ant nest.
RESUMO: Atta sexdens rubropilosa (cortadeira de folha) possui associação simbiótica com fungos e interação negativa com outros fungos devido ao parasitismo do fungo cultivado pelas formigas. Quando colônias da formiga cortadeira de folhas são submetidas ao tratamento com iscas tóxicas, diversas espécies de fungos surgem dentro da colônia, podendo contribuir com a morte ou sobrevivência da colônia. Para entender os relacionamentos ecológicos em colônias de formigas, a identificação de espécie de fungos se torna muito importante e, o uso de DNA barcoding tem sido um método rápido e eficiente para identificação de espécies usando métodos moleculares. No presente trabalho, usamos a região ITS (internal transcribed spacer) para identificar fungos em colônias tratadas com iscas tóxicas. Dois experimentos com iscas tóxicas foram aplicados: 0.75g de Fipronil [0.003%] e 0.75g de Sulfluramid [0.3%]. As amostras, contendo os possíveis fungos, foram coletadas e cultivadas em meio Czaped durante sete dias para o crescimento do fungo e posterior identificação. O DNA total foi isolado de 100-150mg de micélio usando o método CTAB, usado para amplificar a região ITS por PCR empregando primers universais (ITS5 e ITS4). O sequenciamento foi realizado utilizando o método de Sanger. As sequências foram submetidas ao BLAST, permitindo identificar nove diferentes espécies das ordens Agaricales, Eurotiales, Hypocreales, Pleosporales, Saccharomycetales e Tremellales, mostrando variação 96-100% de identidade. Empregando a análise “The Automatic Barcode Gap Discovery”, identificou-se nove grupos, correspondendo as espécies descritas no NCBI. As distâncias K2P foram usadas para gerar uma árvore usando Neighbour-Joining, apresentando que as espécies foram agrupadas de acordo com as filogenias dos grupos. Conclui-se que as colônias de formigas cortadeira de folhas apresentam grande diversidade de fungos e que DNA barcoding é eficiente para identificação destes.
ABSTRACT This study investigated the stimuli that trigger digging behavior in Acromyrmex subterraneus during nest building. The hypothesis was that the presence of the fungus garden and/or brood triggers the excavation of tunnels and chambers. For the experiment, the excavation rate of individually marked workers kept in plastic cylinders filled with soil was recorded. Four treatments were applied: (1) 30 medium-sized workers, 5 g fungus garden and 30 brood items (larvae and pupae); (2) 30 medium-sized workers and 5 g fungus garden; (3) 30 medium-sized workers and 30 brood items; (4) 30 medium-sized workers without fungus and brood. After 24 h, morphological parameters of nest structure (length and width of the chambers and tunnels in cm) and the volume of excavated soil were recorded. In contrast to the expected findings, no change in morphological structure, rate of excavation by workers, or volume of excavated soil was observed between treatments, except for tunnel width, which was greater, when no brood or fungus garden was present. Thus, the results do not support the hypothesis that the fungus garden and/or brood are local stimuli for nest excavation or that they mold the internal architecture of the nest. Although this hypothesis was confirmed for Acromyrmex lundii and Atta sexdens rubropilosa, the same does not apply to A. subterraneus. The digging behavior of workers is probably the result of adaptation during nest building in different habitats.
ABSTRACT 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.
Protein content of leaf-cutting ant queens before the nuptial flight and during the post-claustral phase. This study evaluated the crude protein content of queens of Atta sexdens before the nuptial flight and after the claustral phase in laboratory and field colonies. The hypothesis was that protein is used for survival of the queen and for early colony growth during the claustral phase. Additionally, the nest morphology, live biomass and adult population of field colonies were evaluated. Crude protein was determined by digestion of the organic material with sulfuric acid at high temperatures. The mean crude protein content was 123.23 ± 11.20 mg for females before the nuptial flight and 70.44 ± 12.21 mg for laboratory-reared queens after the claustral phase. The post-claustral crude protein content of field-collected queen was 55.90 ± 9.18 mg. With respect to the loss of crude protein as a function of duration of the claustral phase, laboratory-reared queens lost 52.79 mg and field-collected queens lost 67.33 mg compared to females before the nuptial flight. A positive linear correlation was observed between the weight of field-collected queens (256.4 ± 36.3 mg) and colony biomass (13.02 ± 9.12 g), but there was no correlation between biomass and nest depth (13.11 ± 3.82 cm). As expected, the present results support the hypothesis that protein is used for survival of the queen and for early colony growth, as demonstrated by the reduction in crude protein content as a function of duration of the claustral phase. To our knowledge, this is the first study to provide data of the dynamics of protein reserves in leaf-cutting ant queens during the claustral phase.
The aim of this work was study the selectivity of insecticides in favor of natural enemies in cotton (Gossypium hirsutum latifolium Hurtch Lr), DeltaOpal cultivar, in the city of Malhada (BA), and to know the associated beneficial fauna. The study was conducted at the agricultural year of 2010/2011. The design was conducted in randomized blocks with six treatments and four replications. The treatments were: (1) Fipronil 200 SC (0.38 L.ha-1); (2) Alphacypermethrin 100 SC (0.30 L.ha-1), (3) Lufenuron 50 EC (0.30 L.ha-1), (4) Imidacloprid 200 SC (0.30 L.ha-1), (5) Methyl parathion 600 EC (1.00 L.ha-1), and (6) control (water). The product was applied 80 days after emergence, and the evaluations were performed one day before application and 1, 7 and 14 days after application (DAA). The samples were taken using the sampling method beating cloth and Moericke traps. Natural enemies were brought to the laboratory for sorting, counting and identification by family. The toxicity of the products ranged according to the group of natural enemies. Imidacloprid is selective to the spiders and insecticides are moderately toxic (Methyl Parathion and Alphacypermethrin: 1 and 14th DAA; Lufenuron: 14th DAA) or toxic (Fipronil and Alphacypermethrin: 7thDAA). Fipronil (1 DAA), Alphacypermethrin (7th DAA) and Methyl Parathion (14th DAA) are moderately toxic to adult ladybirds. The analyzed insecticides are toxic to the larvae of ladybirds, with more impact until seven days after the application, with the exception of Methyl Parathion classified, as innocuous until this period. The occurrence of 13 families of spiders and 18 families of parasitic Hymenoptera is registered in cotton agroecosystems in the region of Malhada, in the state of Bahia.
O objetivo foi estudar a seletividade de inseticidas aos inimigos naturais na cultura do algodão (Gossypium hirsutum L.r. latifoliumHurtch), cultivar DeltaOpal, no município de Malhada (BA) e conhecer a fauna benéfica associada. O trabalho foi conduzido na safra 2010/2011, com delineamento experimental em blocos ao acaso, com seis tratamentos e quatro repetições, sendo os tratamentos: (1) Fipronil 200 SC (0,38 L.ha-1); (2) Alfacipermetrina 100 SC (0,30 L.ha-1); (3) Lufenuron 50 CE (0,30 L.ha-1); (4) Imidacloprid 200 SC (0,30 L.ha-1); (5) Paration Metil 600 CE (1,00 L.ha-1); e (6) Testemunha (água). A aplicação dos produtos foi feita 80 dias após a emergência, com avaliações um dia antes da aplicação e 1, 7 e 14 dias após a aplicação (DAA) por meio do pano de batida e armadilha Moericke. Em laboratório, os insetos foram triados, contados e identificados em famílias. A toxicidade dos produtos varia em função do grupo do inimigo natural. A Imidacloprida é seletiva às aranhas, sendo os demais inseticidas medianamente tóxicos (Alfacipermetrina e Paration Metil: 1º e 14º DAA; Lufenuron: 14º DAA) ou tóxicos (Fipronil e Alfacipermetrina: 7º DAA). Fipronil (1º DAA), Alfacipermetrina (7º DAA) e Paration Metil (14º DAA) são medianamente tóxicos aos adultos de joaninhas. Os inseticidas estudados são tóxicos às larvas de joaninhas, com mais impacto até os sete dias após a aplicação, com exceção do Paration Metil, classificado como inócuo até esse período. Registra-se a ocorrência de 13 famílias de aranhas e 18 famílias de hymenópteros parasitoides em agroecossistema de algodão na região de Malhada (BA).
Energetic cost of digging behavior in workers of the leaf-cutting ant Atta sexdens (Fabricius). During nest excavation, leaf-cutting ant workers undergo reduction in their body reserve, particularly carbohydrates. In order to estimate the energetic cost of digging, groups of 30 workers of the leaf-cutting ant Atta sexdens were sealed in a hermetic chamber for 24, 48 and 72 hours, with and without soil for digging, and had the CO2 concentration measured using respirometric chambers as well as volume of soil excavated (g). As expected, the worker groups that carried out soil excavation expelled more carbon dioxide than the groups that did not excavate. Therefore, a worker with body mass of 9.65 ± 1.50 mg dug in average 0.85 ± 0.27 g of soil for 24 hours, consuming ca. 0.58 ± 0.23 J. In this study, we calculate that the energetic cost of excavation per worker per day in the experimental set-up was ca. 0.58 J.
The knowledge of the workers energy content is essential to measure the energy availability for maintenance and performance of activities essences for the colony growth. But little is known about the workers energy content, and how much will be available to carry out activities, for example, the excavation of the nest. The present study determined the lipid content and energy content of the worker ants inactive before and after excavation activity. Through the lipids determination, it can be calculated the energy content of workers resting (standing) with those which excavated. The lipid content and energy content of the workers were on average 9.1±0.8% and energy content of the workers was on average 111.31±54.71J, respectively, however, the experimental series did not differ significantly. Additionally, catabolic flux rate based in workers body mass was 14.76±10.11µW. It was concluded that the energy resource for the excavation of the nest is not coming from reserve lipid body, and thus the energy content of the workers did not change before and after excavation activity.
O conhecimento do conteúdo energético das operárias é essencial para mensurar a disponibilidade energética, responsável pela manutenção e execução de atividades essenciais para o crescimento da colônia de formigas. Mas pouco se conhece sobre o conteúdo energético das operárias e quanto estará disponível para realizar atividades de, por exemplo, escavar do ninho. O presente estudo determinou o teor de lipídeo e o conteúdo energético das operárias de formigas cortadeiras inativas, antes e pós atividade de escavação. Por meio da determinação do teor de lipídeos, pode-se calcular o conteúdo energético das operárias em repouso (paradas) e compará-las com as que escavaram. O teor de lipídeo e conteúdo energético das operárias foram em média 9,1±0,8% e 111,31±54,71J, respectivamente, entretanto, as séries experimentais não diferiram significativamente. Adicionalmente, a taxa do fluxo catabólico, embasado na massa corporal das operárias foi de 14,76±10,11µW. Conclui-se que o recurso energético para a escavação do ninho não é proveniente de reserva de lipídeos corporal e, dessa forma, o conteúdo energético das operárias não alterou antes e pós-atividade de escavação.
Does the social life entail greater individual activity, and consequently, higher energy expenditure? To answer this question, we hypothesized that there is higher CO2 production, when we increase the size of the group of workers, and hence a higher energy cost to the individual when they are in groups. Thus, groups of 10, 20, 30, 40 and 50 workers were sealed in a hermetic chamber for 24 hours. Subsequently, we performed the measurements of the CO2 concentration in the containers respirometric. Unlike the expected CO2 production, and consequently the individual energy expenditure did not differ when we increase the size of the group of workers. Thus, we refuted the hypothesis that the group size leads to a higher cost individual energy, since the greater interaction between individuals. In conclusion, our study with Atta sexdens rubropilosa workers determined that the size of the group does not lead to higher energy costs individual and CO2 production, and therefore energy expenditure similar individual, independent of the group size.
Será que a vida em grupo acarreta uma maior atividade individual, e consequentemente, um maior gasto energético? Para responder a essa questão, hipotetizou-se que exista uma maior produção de CO2, quando se aumenta o tamanho do grupo de formigas operárias e, consequentemente, um maior custo energético ao indivíduo quando está em grupo. Assim, grupos de 10, 20, 30, 40 e 50 operárias foram fechados em uma câmara hermética, durante 24 horas. Posteriormente, efetuou-se a medição das concentrações de CO2 nos recipientes respirométricos. Ao contrário do esperado, a produção de CO2, e consequentemente, o gasto energético individual, não diferiram estatisticamente quando se aumentou o tamanho do grupo de operárias. Dessa forma, refuta-se a hipótese de que o tamanho do grupo conduz a um maior custo energético individual, haja vista a maior interação entre os indivíduos. O estudo com operárias de Atta sexdens rubropilosa evidenciou que o tamanho do grupo não conduz a um maior custo energético individual, sendo a produção de CO2 e, consequentemente, o gasto energético individual similar, independente do tamanho do grupo.
Nest digging spends a lot of energy existing a question about how much energy is required to dig the tunnel and initial chamber. It was hypothesized that the lipid content is used during nest digging. This hypothesis was tested by comparing the consequences of increasing digging effort in queens that were experimentally stimulated to excavate a complete founding nest either once, twice or three times consecutively, compared to control queens that didn't dig. Weight and lipid content of queens were quantified. Results showed that, in contrast with the initial expectations, weight and lipid content were not affected by the increased digging effort in the experimentally-induced successive excavations. It was conclude that the excavation by the queens did not affect the percentages of lipids and consequently the energy content, in their bodies. Probably, energy resources for the excavation wasn't originated from lipid reserves, but from other energy sources, perhaps carbohydrates.
As formigas cortadeiras, importantes pragas agrícolas, anualmente realizam a fundação de novas colônias. Para o início de novas colônias, é preciso a escavação de túneis e de câmaras no solo, sendo que, para isso, as rainhas recém fecundadas gastam muita energia, no entanto a quantificação dessa energia gasta é desconhecida. Nossa hipótese é que a reserva lipídica, armazenada no corpo da rainha, seja utilizada durante a escavação do ninho. Testamos essa hipótese comparando o aumento do esforço de escavação das rainhas, as quais foram experimentalmente estimuladas a escavar uma, duas ou três vezes consecutivas, em relação ao controle, ou seja, em relação às rainhas que não escavaram. Foram quantificados a massa corporal e o teor de lipídios das rainhas. Os resultados mostraram que, ao contrário de nossas expectativas iniciais, massa e teor de lípideos não foram afetadas pelo aumento do esforço de escavação do ninho. Conclui-se que a escavação pelas rainhas não afetou os percentuais de lipídios em seu corpo, consequentemente, o conteúdo de energia. Provavelmente, os recursos energéticos para a escavação não se originam de fontes lipídicas, mas de outros, provavelmente carboidratos.
Annually, mature colonies of Atta ants produce winged males and females, where leave the colony in which they were produced to form new colonies and thus continue the species perpetuation. The foundation of Atta spp. colonies always involves high queen effort, solely responsible for growing the fungus and the care with itself and its offspring. During the foundation there is consumption of body reserves. This study investigated how the environment influences the development of newly founded colonies of leaf cutting ant, Atta sexdens rubropilosa. Therefore, it was compared field colonies collected five months after the nuptial flight and colonies maintained in the laboratory since the nuptial flight. It was analyzed the weight and size of the population (number of workers, larvae, pupae and eggs), the workers size, the volume and weight of the fungus garden and queen effort for the nest foundation (lipid content and weight of queens). In comparison to the field colonies, the laboratory colonies showed higher values in the weight and size of population, the volume and weight of the fungus garden. Measures of workers by class size did not vary between colonies from field and laboratory. The queen effort for nest foundation was higher in field colonies, which showed a lower percentage of fat and lower weight compared to laboratory colonies. These results show that the environment has a strong influence on the colonies development during the foundation, as well as on the physiological status of the queens, and therefore the survival, development and success of the colony, it is a reflection of the queen efforts and of the environment conditions.
Anualmente, as colônias maduras de Atta spp. produzem formigas aladas, machos e fêmeas, que abandonam a colônia na qual foram produzidas para formarem novas colônias e, dessa forma, continuarem a perpetuação da espécie. A fundação de colônias de Atta spp. sempre envolve grande esforço da rainha, única responsável pelo cultivo do fungo e pelos cuidados consigo mesma e com sua prole. Nesse período de fundação ocorre o consumo de grande parte de suas reservas. O presente estudo investigou como o ambiente influencia o desenvolvimento das colônias recém-fundadas de Atta sexdens rubropilosa. Para tanto, foram comparadas colônias de campo coletadas cinco meses após a revoada e colônias mantidas em laboratório desde o voo nupcial. Foram analisados o peso e o tamanho da população (número de operárias, de larvas, de pupas e de ovos), o tamanho das operárias, o volume e peso do jardim de fungo e o esforço para a fundação dos ninhos (teor de lipídeos e peso das rainhas). Comparadas às colônias de campo, as colônias de laboratório apresentaram maiores valores no tamanho e no peso da população, no volume e no peso do jardim de fungo. As medidas das operárias, por classe de tamanho, não variaram entre as colônias de campo e de laboratório. O esforço da fundação dos ninhos foi maior nas colônias de campo, cujas rainhas apresentaram menor porcentagem de lipídeos e menor peso em relação às colônias de laboratório. Esses resultados demonstram que o ambiente exerce forte influência no desenvolvimento das colônias durante a fase de fundação, bem como sobre o status fisiológico das rainhas, sendo, portanto, a sobrevivência, o desenvolvimento e o sucesso da colônia reflexos das condições do ambiente e do esforço da rainha.