ABSTRACT
Seeds of Mimosa bimucronata are heavily infested (pre-dispersal predation) by the bruchid beetle Acanthoscelides schrankiae in Brazil. In this study, firstly we set up experiments to assess seed germination under seven and six different light and temperature regimes, respectively, and then we evaluated the ability of seeds to germinate after predation. We tested the hypothesis that the non-predated seeds from infested fruits may respond differently when set for germination than those seeds of non-infested fruits. We also hypothesized that predation may increase the production of unviable seeds. Seeds under 18 hours of light presented the highest percentage of germination, and the alternating temperature 20-30 °C was considered as optimum for germination (abnormal seedlings were not considered as a successful germination). Germination of seeds from non-infested fruits was significantly higher than germination of non-predated seeds from infested fruits, and predation also caused a significant increase in the proportion of dead seeds. Our results also show a positive correlation between proportions of unviable seeds and predated seeds. These results demonstrated that seeds of M. bimucronata are strongly affected by predation because predated seeds did not germinate and non-predated seeds had their viability reduced when located in infested fruits, supporting our hypothesis.
Subject(s)
Animals , Coleoptera/physiology , Germination/physiology , Mimosa/parasitology , Predatory Behavior , Seeds/parasitology , Light , Seeds/growth & development , TemperatureABSTRACT
Com o objetivo de conhecer os insetos associados às sementes de uma espécie de leguminosa nativa do Brasil, Lonchocarpus muehlbergianus Hassl., frutos foram coletados de árvores isoladas no Município de Três Barras, Paraná, Brasil. Uma amostra de 500 g de frutos com 2353 sementes foi avaliada em laboratório. Foram registradas 77,4% de sementes não danificadas por insetos, 12,4% de sementes danificadas e 10,2% de sementes chochas. A espécie de Bruchidae Ctenocolum crotonae (Fåhraeus) foi detectada pela primeira vez nessa planta. Esta espécie já havia sido registrada no estado do Mato Grosso, Brasil, e neste trabalho, sua distribuição geográfica é ampliada para o estado do Paraná. Horismenus missouriensis Ashmead (Hymenoptera: Eulophidae) também foi observada naamostra e provavelmente é um parasitóide da larva ou pupa do bruquídeo. Do total de 2353 sementes,4,9% foram danificadas por C. crotonae e 4,6% apresentavam orifícios de emergência de H. missouriensis. Larvas de Tenebrionidae e Curculionidae foram detectadas predando as sementes erepresentaram um dano de 2,8% do número total de sementes.
To find the insects associated with seeds of a Brazilian native leguminous plant,Lonchocarpus muehlbergianus Hassl., fruits were collected from isolated trees in Tres Barras, Parana, Brazil. A sample of 500 g of fruits with 2353 seeds was evaluated in the laboratory. It was found that 77.4% of the seeds were not damaged by insects, 12.4% of the seeds were damaged and 10.2% of the seeds were empty. The bruchid species Ctenocolum crotonae (Fåhraeus) was detected for the first time in this plant. This species was recorded in Mato Grosso, Brazil and, in this paper, the geographical distribution is amplified to include Parana State. Horismenus missouriensis Ashmead (Hymenoptera:Eulophidae) was also observed in the sample and it is probably a parasitoid of the bruchid larva or pupa. Of the 2353 seeds, 4.9% were damaged by C. crotonae and 4.6% had emergence holes of H. missouriensis. Larvae of Tenebrionidae and Curculionidae were also detected feeding on the seeds, representing 2.8% of the total number of the seeds.