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Susceptibilidade de Cydia splendana ao fungo entomopatogénico Beauveria bassiana
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Advisor(s)
Abstract(s)
Os fungos entomopatogénicos têm-se revelado uma alternativa promissora aos produtos químicos usados na luta
contra pragas. Apesar do grande esforço empreendido na sua utilização, o seu efeito num grande número de
pragas é ainda desconhecida. O bichado da castanha, Cydia splendana L., é a principal praga do castanheiro no
norte de Portugal, causando prejuízos consideráveis. A utilização de meios de luta químicos apresenta limitações
devido, por um lado, ao número reduzido de substâncias homologadas, e por outro porque a utilização de
pesticidas de síntese não se coaduna com o modo de produção sustentável em que os soutos são conduzidos na
região. Adicionalmente os meios de luta culturais e biotécnicos têm-se revelado de difícil implementação e de
eficácia reduzida. Com o presente trabalho pretendeu-se avaliar a susceptibilidade de C. splendana ao fungo
entomopatogénico Beauveria bassiana. Testou-se o efeito de quatro isolados (A39GF09; A67GF09; LC39GF10
e PA95GF10) da colecção do IPB, obtidos de larvas do lepidóptero Prays oleae recolhidos na região de Trás-os-
Montes. Para tal em laboratório, foram inoculadas larvas de C. splendana, pelo método de superfície, com seis
concentrações de conídios (1 x 105; 1 x 106; 5 x 106; 1 x 107; 5 x 107; 1 x 108). Os quatro isolados de B. bassiana
testados demonstraram capacidade para infectar as larvas de C. splendana. A mortalidade confirmada apresentou
uma correlação linear positiva com a concentração de conídios, embora com diferenças entre isolados. O Tempo
Letal médio (LT50) e a Concentração Letal média (LD50) foram também variáveis entre isolados. A LD50 variou
entre < 1 x 105 (LC39GF10) e 2,13 x 105 (A67GF09), enquanto que LT50 variou entre < 5 e 10 dias. A acção dos
isolados de B. bassiana testados sobre C. splendana, apesar da grande variabilidade observada, abre a
possibilidade do seu uso na luta biológica contra esta praga do castanheiro.
Entomopathogenic fungi are one of the most promising alternatives to the use of chemical pesticides. Although a considerable amount of knowledge is available on this kind of fungi, their effect in a great number of pests is still unknown. The chestnut fruit moth, Cydia splendana L., is one of the major pests of chestnut in northern Portugal, able to cause severe damage. The chemical control has several limitations either due to the limited number of approved substances or because the use of chemical pesticides is not consistent with the sustainable mode of production in which the groves are conducted in the region. Additionally, both cultural and biotechnical controls have proven to be difficult to implement and to have reduced efficacy. This works intends to evaluate the susceptibility of C. splendana to the entomopathogenic fungus Beauveria bassiana. The four isolates tested (A39GF09; A67GF09; LC39GF10 and PA95GF10) were obtained from the IPB collection and were isolated from Prays oleae larvae collected in the Trás-os-Montes region. For this, C. splendana larvae were inoculated, following the surface method, with six concentrations of conidia (1 x 105; 1 x 106; 5 x 106; 1 x 107; 5 x 107; 1 x 108). Larvae of C. splendana showed to be susceptible to infection by all four B. bassiana isolates. A concentration-dependent mortality was observed, although with variation between isolates. Median lethal time (LT50) and median lethal concentration (LD50) also varied between isolates. LD50 varied from < 1 x 105 (LC39GF10) to 2.13 x 105 (A67GF09) while LT50 ranged from < 5 to 10 days These results show an expected variation between isolates of B. bassiana, and, more importantly, the susceptibility of C. splendana to this entomopathogenic fungus, which open up the possibility of its used to control this particular pest.
Entomopathogenic fungi are one of the most promising alternatives to the use of chemical pesticides. Although a considerable amount of knowledge is available on this kind of fungi, their effect in a great number of pests is still unknown. The chestnut fruit moth, Cydia splendana L., is one of the major pests of chestnut in northern Portugal, able to cause severe damage. The chemical control has several limitations either due to the limited number of approved substances or because the use of chemical pesticides is not consistent with the sustainable mode of production in which the groves are conducted in the region. Additionally, both cultural and biotechnical controls have proven to be difficult to implement and to have reduced efficacy. This works intends to evaluate the susceptibility of C. splendana to the entomopathogenic fungus Beauveria bassiana. The four isolates tested (A39GF09; A67GF09; LC39GF10 and PA95GF10) were obtained from the IPB collection and were isolated from Prays oleae larvae collected in the Trás-os-Montes region. For this, C. splendana larvae were inoculated, following the surface method, with six concentrations of conidia (1 x 105; 1 x 106; 5 x 106; 1 x 107; 5 x 107; 1 x 108). Larvae of C. splendana showed to be susceptible to infection by all four B. bassiana isolates. A concentration-dependent mortality was observed, although with variation between isolates. Median lethal time (LT50) and median lethal concentration (LD50) also varied between isolates. LD50 varied from < 1 x 105 (LC39GF10) to 2.13 x 105 (A67GF09) while LT50 ranged from < 5 to 10 days These results show an expected variation between isolates of B. bassiana, and, more importantly, the susceptibility of C. splendana to this entomopathogenic fungus, which open up the possibility of its used to control this particular pest.
Description
Keywords
Cydia splendana Beauveria bassiana Luta biológica Variabilidade
Citation
Oliveira, Ivo; Baptista, Paula; Lino-Neto, Teresa; Bento, Albino; Pereira, J.A. (2014). Susceptibilidade de Cydia splendana ao fungo entomopatogénico Beauveria baciana. VII Congreso Ibérico de Agroingeniería y Ciencias Hortícolas. Madrid. p. 1890-1895. ISBN 978-84-695-9055-3