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Master's Dissertation
DOI
https://doi.org/10.11606/D.11.2020.tde-07052020-094738
Document
Author
Full name
Isabella Bueno
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2020
Supervisor
Committee
Godoy, Wesley Augusto Conde (President)
Sujimoto, Fernando Ribeiro
Bento, Jose Mauricio Simoes
Moral, Rafael de Andrade
Title in Portuguese
Dinâmica do crescimento do fungo simbionte e estruturação de castas em formigas-cortadeiras (Hymenoptera: Formicidae: Atta)
Keywords in Portuguese
Atta sexdens
Dinâmica de crescimento
Fungo simbionte
Proporções de castas
Abstract in Portuguese
As formigas-cortadeiras promovem o corte e o carregamento de folhas para dentro dos seus ninhos a fim de cultivar o fungo simbionte obrigatório que é utilizado como principal fonte alimentar e abrigo para a prole. Atta é um dos dois gêneros existentes e ocorre em quase todo território brasileiro, causando impactos ecológicos positivos, mas também econômicos negativos em diversas culturas, principalmente florestais. O cultivo do fungo simbionte através da vegetação fresca depende de uma divisão de trabalho específica entre as castas polimórficas, que vão desde o preparo do substrato e o cuidado com a prole, até o corte e carregamento das folhas, além da defesa da colônia. Esse estudo teve como objetivo compreender a dinâmica de crescimento da colônia, essencialmente baseando-se na relação entre o crescimento do fungo simbionte e as proporções de indivíduos da subcasta generalista. A dinâmica de crescimento do fungo foi estudada com diferentes proporções de generalistas, ou seja 100%, 50% e 10%. Além disso, o comportamento de corte e transporte de folhas pelos indivíduos remanescentes da colônia foi avaliado. Em relação ao efeito da interação entre o tratamento e a tendência temporal, o crescimento dos fungos nos três tratamentos apresentaram flutuações temporais, no entanto o crescimento final do volume dos jardins de fungo foi semelhante nos três tratamentos, indicando que possivelmente algum mecanismo homeostático atua na colônia em resposta a perda de operárias. Encontramos também variações em variáveis comportamentais e mudanças no grau de agregação dos indivíduos remanescentes em resposta a perda de operárias.
Title in English
Growth dynamics of symbiote fungus and caste structure in leaf-cutting ants (Hymenoptera: Formicidae: Atta)
Keywords in English
Atta sexdens
Caste ratio
Growth dynamics
Symbiont fungus
Abstract in English
Leaf-cutting ants promote the cutting and loading of leaves into their nests in order to grow the obligatory symbiotic fungus which is used as the main food source and shelter for the offspring. Atta is one of the two existing genera and occurs in almost all Brazilian territory, causing positive ecological impacts, but also negative economic impacts on several crops, especially forest. Cultivation of symbiotic fungus through fresh vegetation depends on a specific division of labor among polymorphic castes, ranging from substrate preparation and care of the offspring, to leaf cutting and loading, as well as the defense of the colony. This study aimed to understand the growth dynamics of the colony, essentially based on the relationship between the growth of the symbiote fungus and the ratios of generalist subcaste individuals. The fungus growth dynamics were studied with different ratios of generalists, i.e. 100%, 50% and 10%. In addition, leaf cutting and transport behavior by the remaining individuals of the colony were evaluated. Regarding the effect of the interaction between the treatment and the temporal tendency, the fungal growth in the three treatments showed temporal fluctuations. However, the final growth of the fungal garden volume was similar in the three treatments, likely indicating that some homeostatic mechanisms act on the colony growth in response to loss of workers. We also found variations in behavioral variables and changes in the degree of aggregation of the remaining individuals in response to worker loss.
 
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Publishing Date
2020-05-08
 
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