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O castanheiro europeu Castanea sativa (Mill.) e seus frutos são uma importante fonte de
renda em Portugal na região de Trás-os-Montes. Dentre as pragas que atacam a espécie,
destacam-se a Cydia splendana (Hübner, 1799) e o Curculio elephas (Gyllenhal, 1836):
insetos que causam danos significativos nas castanhas inviabilizando o produto e gerando
perda de produção. Buscando diminuir o dano destas pragas, e o impacto negativo que
os químicos podem trazer ao meio ambiente, surgem alternativas de controlo biológico.
Entre elas, está o uso de fungos entomopatogénicos como a Beauveria bassiana, porém,
sua efetividade varia de acordo com a cepa que é utilizada, com as condições ambientais
e experimentais que está submetida e com as características dos insetos. Nesse sentido,
o objetivo do estudo foi avaliar em campo a eficácia de três estirpes de B. bassiana contra
C.splendana e C.elephas em três diferentes tempos de aplicação das larvas, no intuito de
avaliar o período da viabilidade de uma aplicação do fungo no solo. O experimento foi
conduzido em um souto localizado na freguesia de Samil, no distrito de Bragança,
Portugal. Foram avaliados quatro tratamentos, isolado LC39GF10 (TA) e isolado
A67GF09 (TB) (regionais), Controlo - água destilada (TC) e isolado ATCC74040 (TD)
(comercial) - com concentração de conídios de (1x108) em todos respetivamente. Cada
tratamento possuiu 18 vasos, cada um com dez larvas de cada uma das pragas, colocadas
na superfície dos vasos, em três diferentes tempos após a pulverização dos fungos nos
respetivos vasos e instalação em campo. (T1) colocadas após 1 dia da instalação, (T2)
após oito dias e (T3) após 15 dias. As larvas foram retiradas em duas estações, em que
após, as culturas fúngicas foram isoladas em laboratório e a confirmação da mortalidade
pelo fungo foi feita por análise molecular. Os resultados obtidos demonstraram que nas
condições testadas, os isolados regionais (TA) e (TB) tiveram um melhor desempenho
que o comercial (TD); com maior eficácia de infecção das larvas nos tempos (T1) e (T2);
com mortalidade superior para C. splendana. B. bassiana nas condições testadas,
demonstra potencial de uso na proteção integrada de pragas.
The European chestnut Castanea sativa (Mill.) and its fruits are an important source of income in Portugal, particularly in the Trás-os-Montes region. Among the pests affecting this species, Cydia splendana (Hübner, 1799) and Curculio elephas (Gyllenhal, 1836) stand out as insects causing significant damage to the chestnuts, rendering the product unviable and leading to production losses. In an effort to reduce the damage caused by these pests and the negative environmental impact of chemical treatments, biological control alternatives have emerged. One such method is the use of entomopathogenic fungi like Beauveria bassiana. However, its effectiveness varies depending on the strain used, environmental and experimental conditions, and the characteristics of the insects. In this context, the objective of the study was to evaluate, in the field, the efficacy of three B. bassiana strains against C. splendana and C. elephas across three different larval application times, aiming to assess the duration of the fungus's viability when applied to the soil. The experiment was conducted in a chestnut orchard located in the parish of Samil, in the district of Bragança, Portugal. Four treatments were evaluated: the LC39GF10 isolate (TA) and the A67GF09 isolate (TB) (regional isolates), a control with distilled water (TC), and the ATCC74040 isolate (TD) (commercial isolate), all applied at a conidial concentration of (1x10⁸). Each treatment involved 18 pots, each containing ten larvae of each pest species placed on the surface of the pots at three different times after the fungal spray application and field installation. The timings were: (T1) one day after installation, (T2) eight days after, and (T3) 15 days after. The larvae were retrieved in two stages, after which fungal cultures were isolated in the laboratory, and mortality due to the fungus was confirmed by molecular analysis. The results demonstrated that, under the tested conditions, the regional isolates (TA and TB) performed better than the commercial isolate (TD), achieving higher infection efficacy on the larvae during (T1) and (T2) timings, with greater mortality observed for C. splendana. B. bassiana, under the tested conditions, shows potential for use in integrated pest management.
The European chestnut Castanea sativa (Mill.) and its fruits are an important source of income in Portugal, particularly in the Trás-os-Montes region. Among the pests affecting this species, Cydia splendana (Hübner, 1799) and Curculio elephas (Gyllenhal, 1836) stand out as insects causing significant damage to the chestnuts, rendering the product unviable and leading to production losses. In an effort to reduce the damage caused by these pests and the negative environmental impact of chemical treatments, biological control alternatives have emerged. One such method is the use of entomopathogenic fungi like Beauveria bassiana. However, its effectiveness varies depending on the strain used, environmental and experimental conditions, and the characteristics of the insects. In this context, the objective of the study was to evaluate, in the field, the efficacy of three B. bassiana strains against C. splendana and C. elephas across three different larval application times, aiming to assess the duration of the fungus's viability when applied to the soil. The experiment was conducted in a chestnut orchard located in the parish of Samil, in the district of Bragança, Portugal. Four treatments were evaluated: the LC39GF10 isolate (TA) and the A67GF09 isolate (TB) (regional isolates), a control with distilled water (TC), and the ATCC74040 isolate (TD) (commercial isolate), all applied at a conidial concentration of (1x10⁸). Each treatment involved 18 pots, each containing ten larvae of each pest species placed on the surface of the pots at three different times after the fungal spray application and field installation. The timings were: (T1) one day after installation, (T2) eight days after, and (T3) 15 days after. The larvae were retrieved in two stages, after which fungal cultures were isolated in the laboratory, and mortality due to the fungus was confirmed by molecular analysis. The results demonstrated that, under the tested conditions, the regional isolates (TA and TB) performed better than the commercial isolate (TD), achieving higher infection efficacy on the larvae during (T1) and (T2) timings, with greater mortality observed for C. splendana. B. bassiana, under the tested conditions, shows potential for use in integrated pest management.
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Palavras-chave
Castanea sativa Cydia splendana Curculio elephas Beauveria bassiana Controlo de pragas Condições de campo