Crescimento das colônias e desenvolvimento dos ninhos de Atta bisphaerica e Atta capiguara (Hymenoptera: Formicidae)
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Data
2021-09-13
Autores
Farias, Adriano Pimentel [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
As formigas cortadeiras de gramíneas, Atta bisphaerica e Atta capiguara (Formicidae: Myrmicinae: Attini: Attina), são encontradas no bioma Cerrado, frequentemente, como pragas de pastagem, cana-de-açúcar, arroz e milho. Embora as formigas construam ninhos elaborados, pouco foi elucidado sobre o padrão de construção para A. capiguara, bem como o desenvolvimento dos ninhos das duas espécies em função do crescimento da colônia. Desse modo, o objetivo foi estudar o desenvolvimento da arquitetura dos ninhos de A. capiguara; avaliar se os parâmetros dos ninhos (ex.: área externa, câmaras) crescem em proporções semelhantes ao número de operárias de A. bisphaerica; fazer uma análise comparativa entre as espécies sobre parâmetros dos ninhos, bem como avaliar se a área externa dos ninhos de A. capiguara é um parâmetro representativo do crescimento da colônia. O primeiro estudo sobre a arquitetura dos ninhos de A. capiguara foi realizado em ninhos moldados com cimento, enquanto os estudos dos ninhos em função da colônia foram realizados por meio de escavações e coleta da biomassa. Os resultados revelaram que ocrescimento dos ninhos de A. capiguara no primeiro ano e meio de idade é em profundidade. Em seguida, os ninhos cresceram lateralmente pela adição de câmaras e túneis e surgimento das primeiras câmaras de resíduos. Além disso, o volume total das câmaras de resíduos aumenta com o incremento no volume das câmaras de fungo. Para A. bisphaerica, o volume total das câmaras e a área externa do ninho aumentaram em proporções semelhantes ao aumento do número de operárias. O número de câmaras de fungo, número de orifícios de entrada e a profundidade aumentaram em menor proporção. A análise comparativa entre as espécies revelou que as taxas de aumento da área externa, número de câmaras de fungo e profundidade dos ninhos em função do número de operárias não diferiu. Por outro lado, a taxa de aumento do número de orifícios para A. bisphaerica foi maior do que para A. capiguara, enquanto a taxa do volume total das câmaras foi maior para A. capiguara. Portanto, o presente estudo demonstra que o volume total das câmaras de resíduos é proporcional ao volume total das câmaras de fungo de A. capiguara. Para A. bisphaerica, o desenvolvimento do ninho em termos de volume das câmaras é semelhante ao aumento do número de operárias. A análise comparativa entre as espécies revelou que a área externa do ninho é o parâmetro que melhor representa a população da colônia, tanto para a espécie que investe precoce em câmaras de resíduos, como a que investe posteriormente nessa estrutura. Assim, este estudo contribui para o melhor entendimento do crescimento das colônias e desenvolvimento dos ninhos das formigas cortadeiras de gramíneas do gênero Atta.
Grass-cutting ants Atta bisphaerica and Atta capiguara (Formicidae: Myrmicinae: Attini: Attina) are found in the Cerrado biome, frequently as pests of pasture, sugarcane, rice, and corn. Although ants build elaborate nests, little was elucidated about the pattern of A. capiguara nests, as well the nest development of two species as a function of colony growth. Thus, the objective of this study was to evaluate the nest architecture development of A. capiguara; to evaluate if nest parameters (ex.: external area, chambers) grow in similar proportions to worker number of A. bisphaerica; to perform a comparative analysis between species against nest parameters, as well as to assess if external area of A. capiguara nests is a representative parameter of colony growth. The first study of the A. capiguara nest architecture was performed in nests molded with cement, while the studies of nests as a colony function were performed through excavations and biomass collection. The results revealed that the development of A. capiguara nests in the first year and a half of age is in depth. Then, the nests grew laterally by adding chambers and tunnels and the emergence of the first waste chamber. Furthermore, the total volume of waste chambers increases with the increment in the fungus chambers volume. For A. bisphaerica, the total chambers volume and external area of the nest increased in a similar proportion to the increase in the worker number. The number of fungus chambers, number of entrance holes, and depth increased to a lesser proportion. Comparative analysis between colony growth and nest development revealed that the increase rates in the external area, number of fungus chambers and nest depth as a function of the number of workers did not differ between species. On the other hand, the increase rate in number of entrances holes for A. bisphaerica was greater than for A. capiguara, while the rate of total volume of chambers was greater for A. capiguara. Therefore, the present study demonstrates that the total volume of the waste chambers is proportional to the total volume of the fungus chambers of A. capiguara. The development of the A. bisphaerica nests in terms of chamber volume is similar to the increase in the worker number of colonies. The comparative analysis between species revealed that the external area is the parameter that best represents the colony population, both for the specie that invest early in waste chamber and that invests latterly in this structure. Thus, this study contributes to a better understanding of colony growth and nest development of Atta grass-cutting ants.
Grass-cutting ants Atta bisphaerica and Atta capiguara (Formicidae: Myrmicinae: Attini: Attina) are found in the Cerrado biome, frequently as pests of pasture, sugarcane, rice, and corn. Although ants build elaborate nests, little was elucidated about the pattern of A. capiguara nests, as well the nest development of two species as a function of colony growth. Thus, the objective of this study was to evaluate the nest architecture development of A. capiguara; to evaluate if nest parameters (ex.: external area, chambers) grow in similar proportions to worker number of A. bisphaerica; to perform a comparative analysis between species against nest parameters, as well as to assess if external area of A. capiguara nests is a representative parameter of colony growth. The first study of the A. capiguara nest architecture was performed in nests molded with cement, while the studies of nests as a colony function were performed through excavations and biomass collection. The results revealed that the development of A. capiguara nests in the first year and a half of age is in depth. Then, the nests grew laterally by adding chambers and tunnels and the emergence of the first waste chamber. Furthermore, the total volume of waste chambers increases with the increment in the fungus chambers volume. For A. bisphaerica, the total chambers volume and external area of the nest increased in a similar proportion to the increase in the worker number. The number of fungus chambers, number of entrance holes, and depth increased to a lesser proportion. Comparative analysis between colony growth and nest development revealed that the increase rates in the external area, number of fungus chambers and nest depth as a function of the number of workers did not differ between species. On the other hand, the increase rate in number of entrances holes for A. bisphaerica was greater than for A. capiguara, while the rate of total volume of chambers was greater for A. capiguara. Therefore, the present study demonstrates that the total volume of the waste chambers is proportional to the total volume of the fungus chambers of A. capiguara. The development of the A. bisphaerica nests in terms of chamber volume is similar to the increase in the worker number of colonies. The comparative analysis between species revealed that the external area is the parameter that best represents the colony population, both for the specie that invest early in waste chamber and that invests latterly in this structure. Thus, this study contributes to a better understanding of colony growth and nest development of Atta grass-cutting ants.
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Palavras-chave
Insetos sociais, Formigas cortadeiras, Operárias de Atta, Fungicultura, Arquitetura dos ninhos, Social insects, Leaf-cutting ants, Atta workers, Fungiculture, Nest architecture