Resposta comportamental das operárias de Atta sexdens rubropilosa Forel, 1908 (Hymenoptera, Formicidae) a substância química inseticida e fungicida
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Data
2019-01-30
Autores
Sousa, Kátia Kaelly Andrade [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
As formigas cortadeiras Atta (saúvas) e Acromyrmex (quenquéns) são apontadas como as principais pragas de ecossistemas florestais e agrícolas, em razão dos prejuízos que causam ao cortarem as folhas das plantas para o cultivo do fungo simbionte. Esse material vegetal selecionado é transportado para a câmara de fungo, onde passa por várias fases de processamento, desde o corte, à incorporação no jardim do fungo. Tal seleção feita pelas operárias forrageiras é influenciada pelas necessidades nutricionais do jardim de fungo e/ou a ausência de substâncias potencialmente nocivas a colônia. Conhecimento este, evidenciado em estudos que observaram a rejeição de plantas palatáveis quando essas apresentaram substâncias nocivas a colônia, como a cicloheximida (CHX), substância conhecida como fungicida em estudos realizados com formigas cortadeiras. As formigas não são capazes de detectar tal fungicida, mas observa-se uma rejeição retardada, quando o fungicida é incorporado ao jardim de fungo. Esse reconhecimento retardado, hipotetizou que um semioquímico emitido pelo jardim de fungo regula a seleção de plantas por operárias, sendo interpretado como uma comunicação entre o fungo simbionte e as operárias de formigas cortadeiras. Assim, alguns questionamentos são importantes como: as operárias respondem a ação do fungicida alterando seus comportamentos dentro da colônia e quais são? Qual o efeito ocasionado pela a CHX em formigas cortadeiras? Existe uma comunicação através de um volátil semioquimico liberado pelo fungo para promover a rejeição do substrato pelas forrageiras? Visto esses questionamentos, o objetivo desse estudo foi avaliar as alterações comportamentais das operárias de formigas cortadeiras, tempo de carregamento, deposição de lixo, quando sujeitas a presença da CHX, o efeito na mortalidade de formigas cortadeiras por via oral pela ação da CHX e identificar os compostos voláteis liberados pelo jardim de fungo em resposta a CHX, bem como a resposta comportamental das operárias em relação a jardins de fungos saudáveis e não saudáveis. Como resultado o fungicida afetou negativamente e estruturalmente as colônias de formigas cortadeiras. Os comportamentos sofreram aumento nas frequências de lamber o pellet e a limpeza entre as formigas, além disso, ocorreu aumento do tempo de carregamento e mortalidade de operárias encontradas na câmera de lixo no decorrer da incorporação com CHX. Para o estudo da mortalidade observou-se que a CHX em altas concentrações promove a mortalidade de operárias de formigas cortadeiras por ingestão. No entanto, a CHX não pode ser considerado um potencial formicida, devido a sua baixa mortalidade em alta concentração (menor 50%), modo de ação desconhecido para esses insetos, não apresentar ação retardada como a sulfluramida, e ser tóxica ao ser humano e a outros organismos. Além disso, nenhum semicoquímico volátil foi emitido pelo jardim de fungo sob a ação de substâncias deletérias. Portanto, o presente estudo concluiu que os comportamentos realizados durantes a incorporação, sofrem alterações quando presente uma substância nociva a colônia, e a não presença de um semioquímico volátil presente para a comunicação fungo-formigas, além do mais, fato importante é a CHX ocasionar mortalidade em formigas cortadeiras.
Leaf-cutting ants Atta (saúvas) and Acromyrmex (quenquéns) are indicated as the main pests of forest and agricultural ecosystems, due to the damage they cause when cutting the leaves of the plants for the cultivation of the symbiotic fungus. This selected plant material is transported to the fungus chamber, where it goes through various stages of processing, from the cutting, incorporation into the fungus garden. Such selection made by forage workers is influenced by the nutritional needs of the fungus garden and / or the absence of substances potentially harmful to the colony. This knowledge, evidenced in studies that observed the rejection of palatable plants when they presented substances harmful to the colony, such as cycloheximide (CHX), a substance known as fungicide in studies with leaf cutting ants. Ants are not able to detect such fungicide, but a delayed rejection is observed when the fungicide is incorporated into the fungus garden. This delayed recognition hypothesized that a semiochemical emitted by the fungus garden regulates the selection of plants by fodder, being interpreted as a communication between the symbiotic fungus and the workers of cutter ants. Thus, some questions are important as: the workers respond to the action of the fungicide by changing their behavior within the colony and what are? What effect does CHX have on leaf cutting ants? Is there a communication through a volatile semiochemical released by the fungus to promote substrate rejection by forages? Considering these questions, the objective of this study is to evaluate the behavioral alterations of cutter ant workers, loading time, garbage deposition, when subjected to the presence of CHX, the effect on mortality of leaf cutting ants by the action of CHX and to identify the volatile compounds released by the fungal garden in response to CHX, as well as the behavioral response of workers to healthy and unhealthy fungal gardens. As a result, the fungicide adversely and structurally affected the cutting ant colonies. The behaviors were affected by changes in the frequency of pellet licking and cleaning among the ants. In addition, there was an increase in the loading time and mortality of workers found in the trash chamber during the incorporation with CHX. For the study of mortality it was observed that CHX in high concentrations promotes the moderate mortality of cutter ant workers through ingestion. However, CHX can not be considered a potential formicide, due to its low mortality in high concentration (lower 50%), unknown mode of action for insects, no delayed action such as sulfluramide, and being toxic to humans and other bodies. In addition, no volatile semiochemical was emitted by the fungus garden under the action of deleterious substances. Therefore, the present study concludes that the behaviors realized during the incorporation, undergo alterations when a substance harmful to the colony present, and the presence of a volatile semioquímico present for the communication fungus-ants, in addition, important fact is the CHX to cause mortality in leaf cutting ants.
Leaf-cutting ants Atta (saúvas) and Acromyrmex (quenquéns) are indicated as the main pests of forest and agricultural ecosystems, due to the damage they cause when cutting the leaves of the plants for the cultivation of the symbiotic fungus. This selected plant material is transported to the fungus chamber, where it goes through various stages of processing, from the cutting, incorporation into the fungus garden. Such selection made by forage workers is influenced by the nutritional needs of the fungus garden and / or the absence of substances potentially harmful to the colony. This knowledge, evidenced in studies that observed the rejection of palatable plants when they presented substances harmful to the colony, such as cycloheximide (CHX), a substance known as fungicide in studies with leaf cutting ants. Ants are not able to detect such fungicide, but a delayed rejection is observed when the fungicide is incorporated into the fungus garden. This delayed recognition hypothesized that a semiochemical emitted by the fungus garden regulates the selection of plants by fodder, being interpreted as a communication between the symbiotic fungus and the workers of cutter ants. Thus, some questions are important as: the workers respond to the action of the fungicide by changing their behavior within the colony and what are? What effect does CHX have on leaf cutting ants? Is there a communication through a volatile semiochemical released by the fungus to promote substrate rejection by forages? Considering these questions, the objective of this study is to evaluate the behavioral alterations of cutter ant workers, loading time, garbage deposition, when subjected to the presence of CHX, the effect on mortality of leaf cutting ants by the action of CHX and to identify the volatile compounds released by the fungal garden in response to CHX, as well as the behavioral response of workers to healthy and unhealthy fungal gardens. As a result, the fungicide adversely and structurally affected the cutting ant colonies. The behaviors were affected by changes in the frequency of pellet licking and cleaning among the ants. In addition, there was an increase in the loading time and mortality of workers found in the trash chamber during the incorporation with CHX. For the study of mortality it was observed that CHX in high concentrations promotes the moderate mortality of cutter ant workers through ingestion. However, CHX can not be considered a potential formicide, due to its low mortality in high concentration (lower 50%), unknown mode of action for insects, no delayed action such as sulfluramide, and being toxic to humans and other bodies. In addition, no volatile semiochemical was emitted by the fungus garden under the action of deleterious substances. Therefore, the present study concludes that the behaviors realized during the incorporation, undergo alterations when a substance harmful to the colony present, and the presence of a volatile semioquímico present for the communication fungus-ants, in addition, important fact is the CHX to cause mortality in leaf cutting ants.
Descrição
Palavras-chave
Formigas cortadeiras, Comportamentos, Comunicação, Leaf-cutting ants, Behaviors, Communication