Aspectos biológicos e reprodutivos de Selitrichodes neseri (Hymenoptera: Eulophidae) Kelly & La Salle e estabelecimento do parasitoide em plantios florestais de eucalipto no Brasil
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2017-07-07
Autores
Puretz, Barbara de Oliveira [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Árvores do gênero Eucalyptus apresentam alto potencial econômico no setor florestal brasileiro, estão adaptadas às condições edafoclimáticas no Brasil proporcionando crescimento rápido, madeira de qualidade e usos múltiplos. No entanto, esta produção é comprometida por alguns fatores, destacando-se os insetos-praga. Uma das principais pragas exóticas do eucalipto no Brasil é Leptocybe invasa (Hymenoptera: Eulophidae). A fêmea realiza sua oviposição nas nervuras centrais das folhas, pecíolos e ramos, formando galhas, causando redução no crescimento, desfolha e morte da planta. Uma das principais medidas de controle deste inseto é o controle biológico, com o parasitoide exótico Selitrichodes neseri (Hymenoptera: Eulophidae). Neste trabalho foram avaliados a longevidade de adultos de S. neseri em diferentes concentrações de mel e diferentes temperaturas em laboratório, bem como foi realizado a descrição de ovários e sistema reprodutor masculino, e a recuperação de S. neseri em campo. Estes estudos básicos são importantes para analisar o potencial de S. neseri para controle de L. invasa em laboratório e em campo. Para a avaliação da longevidade de S. neseri, fêmeas e machos foram individualizados em tubos de vidro, esses insetos foram coletados recém emergidos, sexados, identificados e colocados nos tubos. Nesse experimento foram oferecidas as seguintes concentrações de mel: mel puro (100%), soluções de mel a 50% e 10% e testemunha (sem alimento). As temperaturas testadas foram 18°C, 22°C, 25°C, 30°C e 34°C. Todos os tratamentos foram conduzidos em câmaras climatizadas com UR de 60 ± 10% e fotoperíodo de 12 h, e avaliados do primeiro dia de emergência até a morte de cada parasitoide. Foi utilizado o teste de Tukey-Kramer ajustado por Sidak. Para descrição dos ovários e sistema reprodutor masculino foram analisadas três amostras, fêmeas acasaladas e virgens de S. neseri e machos de S. neseri, essas amostras foram emblocadas em historesina e submetidas a cortes histológicos de 2 μm. Esses cortes foram observados em miscroscópio de luz e fotografados. Para avaliação da recuperação de S. neseri em campo, os insetos foram liberados em oito estados brasileiros, em empresas florestais, em plantios de eucalipto infestados por L. invasa. Após, aproximadamente, 40 dias as empresas florestais enviaram ramos dos locais de liberação dos parasitoides para avaliação em laboartório, onde foi realizada a identificação e contagem dos insetos que emergiram dos ramos. Na longevidade de adultos de S. neseri a maior sobrevivência foi na temperatura de 22 °C, sendo a temperatura de 34 °C limitante para a longevidade desse inseto. Selitrichodes neseri necessita de uma fonte de carboidrato para aumento na sua longevidade. S. neseri é uma espécie sinovigênica e possui um ovário meroístico politrófico e os testículos dos machos se degeneram na fase adulta. S. neseri foi recuperado em três desses estados brasileiros. Os estudos de longevidade de S. neseri em diferentes condições são importantes para a liberação e estabelecimento desse parasitoide em campo.
Trees of the genus Eucalyptus are economically important to the Brazilian forestry, they have a good adaptation to the edaphoclimatic conditions in Brazil, providing fast growth, quality wood and multiple uses. However, this production is compromised by some factors, especially insect pests. One of the main exotic pest of eucalyptus in Brazil is Leptocybe invasa (Hymenoptera: Eulophidae). The female postures the eggs in the central ridge of the leaves, petioles and branches forming galls, causing growth reduction, defoliation and even plant death. One of the main control measures of this pest is the biological control, with the exotic parasitoid Selitrichodes neseri (Hymenoptera: Eulophidae). In this work the longevity of S. neseri adults in different concentrations of honey and different temperatures in the laboratory, description of ovaries and male reproductive system, and the recovery of S. neseri in the field were evaluated. These basic studies are important to analyze the potential of S. neseri for control of L. invasa in the laboratory and in the field. For the evaluation of the longevity of S. neseri, females and males were individualized in glass tubes, these insects were collected freshly emerged, sexed and identified to this experiment the following concentrations were used: pure honey (100%), 50% honey and 10% honey and control (without food). The temperatures tested were 18, 22, 25, 30 and 34 °C. All treatments were carried out in conditioned chambers with RH 60 ± 10% and of photoperiod 12 h, and evaluated from the first day of emergence until the death of each parasitoid. The Tukey-Kramer test adjusted by Sidak was used. For the description of the ovaries and the male reproductive system, three samples were analyzed, females of S. neseri mates, females of S. neseri virgins and males of S. neseri, these samples were placed in historesin and submitted to 2 μm histological cuts, these cuts were observed in light microscope. To evaluate the recovery of S. neseri in the field, the insects were released in eight Brazilian states, in eucaliptus plantations infested with L. invasa. After approximately forty days the branches samples were sent of the parasitoid release sites for evaluation in the laboratory, where the insects that emerged from the branches were identified and counted. The longevity of S. neseri populations was better was at 22 ° C, the temperature of 34 ° C was limiting for the longevity of this insect. Selitrichodes neseri needs a source of carbohydrate to a increase its longevity. S. neseri is a sinovigenic species and has a meroistic polytrophic ovary and the testicle of males degenerate into adul life. S. neseri were their field establishment in three of these states. The longevity studies of S. neseri in different conditions are important for the release and establishment of this parasitoid in the field.
Trees of the genus Eucalyptus are economically important to the Brazilian forestry, they have a good adaptation to the edaphoclimatic conditions in Brazil, providing fast growth, quality wood and multiple uses. However, this production is compromised by some factors, especially insect pests. One of the main exotic pest of eucalyptus in Brazil is Leptocybe invasa (Hymenoptera: Eulophidae). The female postures the eggs in the central ridge of the leaves, petioles and branches forming galls, causing growth reduction, defoliation and even plant death. One of the main control measures of this pest is the biological control, with the exotic parasitoid Selitrichodes neseri (Hymenoptera: Eulophidae). In this work the longevity of S. neseri adults in different concentrations of honey and different temperatures in the laboratory, description of ovaries and male reproductive system, and the recovery of S. neseri in the field were evaluated. These basic studies are important to analyze the potential of S. neseri for control of L. invasa in the laboratory and in the field. For the evaluation of the longevity of S. neseri, females and males were individualized in glass tubes, these insects were collected freshly emerged, sexed and identified to this experiment the following concentrations were used: pure honey (100%), 50% honey and 10% honey and control (without food). The temperatures tested were 18, 22, 25, 30 and 34 °C. All treatments were carried out in conditioned chambers with RH 60 ± 10% and of photoperiod 12 h, and evaluated from the first day of emergence until the death of each parasitoid. The Tukey-Kramer test adjusted by Sidak was used. For the description of the ovaries and the male reproductive system, three samples were analyzed, females of S. neseri mates, females of S. neseri virgins and males of S. neseri, these samples were placed in historesin and submitted to 2 μm histological cuts, these cuts were observed in light microscope. To evaluate the recovery of S. neseri in the field, the insects were released in eight Brazilian states, in eucaliptus plantations infested with L. invasa. After approximately forty days the branches samples were sent of the parasitoid release sites for evaluation in the laboratory, where the insects that emerged from the branches were identified and counted. The longevity of S. neseri populations was better was at 22 ° C, the temperature of 34 ° C was limiting for the longevity of this insect. Selitrichodes neseri needs a source of carbohydrate to a increase its longevity. S. neseri is a sinovigenic species and has a meroistic polytrophic ovary and the testicle of males degenerate into adul life. S. neseri were their field establishment in three of these states. The longevity studies of S. neseri in different conditions are important for the release and establishment of this parasitoid in the field.
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Palavras-chave
Leptocybe invasa, Longevidade, Controle biológico clássico, Sistema reprodutor, Eucalyptus, Longevity, Classical biological control, Reproductive system