Efeito da predação por Acanthoscelides macrophthalmus (Coleoptera: Chrysomelidae: Bruchinae) na sincronização da germinação e na aptidão de Leucaena leucocephala (Fabaceae: Mimosoideae)
Data
2024-09-05
Autores
Santana, Bárbara Alves 
Orientadores
Rossi, Marcelo Nogueira
Tipo
Trabalho de conclusão de curso
Título da Revista
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Resumo
Interações ecológicas como do tipo predador-presa são muito importantes e muito estudadas em ecologia, pois contribuem para um melhor entendimento das dinâmicas populacionais e da estrutura das comunidades. Porém, as implicações ecológicas de interações predador-presa em sistemas inseto-planta ainda são pouco conhecidas. O objeto do presente estudo foi investigar a emergência e o desempenho de plântulas de Leucaena leucocephala, considerada planta invasora em vários países, quando as sementes são predadas pelo bruquíneo Acanthoscelides macrophthalmus, comparando-se com plântulas de sementes intactas e escarificadas. Foram testadas as hipóteses de que as sementes predadas exibem maior velocidade e sincronia de emergência das plântulas, quando comparadas com sementes intactas, bem como que o tamanho e a sobrevivência das plântulas provenientes de sementes predadas são menores em relação às provenientes de sementes intactas e escarificadas. Frutos foram coletados em três localidades e levados para o laboratório, onde as sementes foram removidas. Cem sementes foram escarificadas, 100 permaneceram intactas e 100 sementes com um orifício característico de emergência do bruquíneo adulto foram separadas. As sementes foram semeadas em tubetes, definindo os três tratamentos experimentais. A velocidade de emergência, o tamanho e a sobrevivência das plântulas foram registradas durante 122 dias. Foi constatado que as plântulas de sementes predadas emergem mais rapidamente que plântulas de sementes intactas, porém, estas plântulas cresceram menos e sobreviveram por menos tempo. As plântulas de sementes escarificadas atingiram tamanhos maiores, emergiram mais rápido e sobreviveram por um tempo maior. Assim, apesar de A. macrophthalmus ser considerado um agente de escarificação natural das sementes de L. leucocephala, sua ação afeta a sobrevivência e o desenvolvimento das plântulas, podendo ser considerado um predador das sementes desta planta.
Ecological interactions such as predator-prey are very important and widely studied in ecology helping the understanding of population dynamics and functioning of community structures. However, the ecological implications of predator-prey interactions in insect-plant systems are poorly known. The aim of this study was to investigate the emergence and fitness of Leucaena leucocephala seedlings, an important invasive plant worldwide, when their seeds are predated by the bruchine Acanthoscelides macrophthalmus, comparing with seedlings from intact and scarified seeds. The following hypotheses were tested: 1) that the predated seeds exhibit greater speed and synchrony on seedling emergence when compared to seedlings from intact seeds, and 2) that seedling size and survival from predated seeds are smaller than those seedlings from intact and scarified seeds. Fruits were collected from three localities and taken to the laboratory where seeds were removed, and 100 seeds were scarified, 100 seeds were left intact and other 100 seeds were classified as predated because they presented the typical bruchine’s emergence hole. All seeds were sown in tubes used for the growing of forest plants, which defined the three experimental groups. The speed of seedling emergence, its size and survival were recorded for 122 days. It was observed that those seedlings from predated seeds emerged faster than those seedlings from intact seeds; however, these seedlings were smaller and presented lower survival. The seedlings from scarified seeds were bigger , emerged faster and presented greater survival than the seedlings from the other experimental groups. Therefore, although A. macrophthalmus causes natural scarification on L. leucocephala seeds, this beetle compromises the survival and the development of L. leucocephala seedlings, acting as a seed predator.
Ecological interactions such as predator-prey are very important and widely studied in ecology helping the understanding of population dynamics and functioning of community structures. However, the ecological implications of predator-prey interactions in insect-plant systems are poorly known. The aim of this study was to investigate the emergence and fitness of Leucaena leucocephala seedlings, an important invasive plant worldwide, when their seeds are predated by the bruchine Acanthoscelides macrophthalmus, comparing with seedlings from intact and scarified seeds. The following hypotheses were tested: 1) that the predated seeds exhibit greater speed and synchrony on seedling emergence when compared to seedlings from intact seeds, and 2) that seedling size and survival from predated seeds are smaller than those seedlings from intact and scarified seeds. Fruits were collected from three localities and taken to the laboratory where seeds were removed, and 100 seeds were scarified, 100 seeds were left intact and other 100 seeds were classified as predated because they presented the typical bruchine’s emergence hole. All seeds were sown in tubes used for the growing of forest plants, which defined the three experimental groups. The speed of seedling emergence, its size and survival were recorded for 122 days. It was observed that those seedlings from predated seeds emerged faster than those seedlings from intact seeds; however, these seedlings were smaller and presented lower survival. The seedlings from scarified seeds were bigger , emerged faster and presented greater survival than the seedlings from the other experimental groups. Therefore, although A. macrophthalmus causes natural scarification on L. leucocephala seeds, this beetle compromises the survival and the development of L. leucocephala seedlings, acting as a seed predator.