Poderá a casta de videira influir na eficácia do uso da confusão sexual contra a traça-da-uva, Lobesia botrana (Lepidoptera: Tortricidae)?
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2021-03-15
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A traça-da-uva, Lobesia botrana, é praga-chave da vinha na Região Demarcada do Douro (RDD). A importância económica desta praga, a par da necessidade de reduzir o uso de inseticidas químicos, tem vindo a despertar particular interesse para o uso da confusão sexual (CS), que está em curso na RDD desde 2000, embora com resultados nem sempre satisfatórios. Com este trabalho pretendeu-se avaliar, através da análise de dados recolhidos entre 2000 e 2019, a influência, na intensidade do ataque da praga, da casta (castas tintas e castas brancas com representatividade na RDD), ano, sub-região e geração do inseto. Por outro lado, através do trabalho realizado em 2019, pretendeu-se avaliar, em quatro castas tintas com diferentes níveis de suscetibilidade ao ataque de L. botrana (Touriga Franca, Tinta Barroca, Touriga Nacional e Sousão), características responsáveis pelas diferenças de suscetibilidade designadamente características morfológicas das inflorescências/cachos (pubescência, peso, comprimento, largura, compactação, volume e número de bagos), a textura dos bagos (resistência à perfuração, compressão e estrutura da película) e a quantificação dos extratos da película (análise química). Os resultados mostram que a intensidade do ataque de traça-da-uva variou de acordo com: (1) a casta (a T. Franca, no caso das castas tintas, e a Malvasia Fina, no caso das castas brancas, foram tendencialmente as mais atacadas); (2) o ano (o ataque variou de acordo com a condições climáticas de cada ano, embora se tenha verificado que, tendencialmente, tem vindo a diminuir ao longo dos anos); e (3) a sub-região (menor intensidade do ataque no Douro Superior, do que no Cima Corgo e Baixo Corgo). Para a mesma data de amostragem, as larvas com origem na T. Franca foram as que, em geral, estavam num instar larvar mais avançado. Dos fatores analisados, a pubescência e a precocidade das inflorescências parecem poder influenciar o ataque da primeira geração, pois as inflorescências de T. Franca eram as que se apresentavam mais desenvolvidas e com menos pubescência. No caso dos cachos, a T. Franca foi a que apresentou maior compactação, o que poderá justificar o maior ataque frequentemente observado. A T. Nacional (uma das castas menos atacadas) foi a que apresentou maior resistência à perfuração. A análise dos extratos das películas das castas T. Franca e Sousão permitiram verificar que a segunda apresentou maior percentagem de peso de extratos da película do que a primeira, o que poderá sugerir alguma relação entre este parâmetro e o ataque observado. Por outro lado, verificou-se que, em ambas as castas, os bagos atacados apresentam maior percentagem de peso de extratos do que os bagos não atacados.
The European Grape Moth (EGM), Lobesia botrana, is a key pest of the vine in the Douro Demarcated Region (DDR). The economic importance of this pest, together with the need to reduce the use of chemical insecticides has been of particular interest in the use of mating disruption (MD), which has been underway in the DDR since 2000, although with results that are not always satisfactory. In this way, through the analysis of data collected from 2000 to 2019, the influence of the grapevine cultivar, the year, the sub-region and the insect generation on EGM infestation. On the other hand, through the work carried out in 2019, four red grape cultivars with different levels of susceptibility to the attack of L. botrana (Touriga Franca, Tinta Barroca, Touriga Nacional and Sousão) were also evaluated, characteristics responsible for the differences in susceptibility, namely morphological characteristics of the inflorescences/bunches (hairiness, weight, length, width, compaction, volume and number of berries), the texture of the berries (resistance to perforation, compression and skin structure) and the quantification of the skin extracts (chemical analysis). The results show that the infestation of EGM varies according to: (1) the grapevine cultivar (T. Franca and Malvasia Fina, in the case of red and white respectively grape varieties tends to be the most infested cultivars); (2) the year (infestation is dependent on the climatic conditions of the year but, tendentially, has been decreasing over the years); and (3) the subregion (lower in the Douro Superior than in the Cima Corgo and Baixo Corgo). In the same sampling date, larvae from T. Franca were those that, in general, were in a more advanced larval instar. Of the analyzed factors, hairiness and early of the inflorescence seem to influence the first generation infestation, since the inflorescences of T. Franca showed more early and less pubescence. In the case of bunches, T. Franca presented the highest compaction index, which could justify the greater preference, frequently observed. T. Nacional (one of the least attacked grape varieties) presented the highest resistance to perforation. The analysis of the extracts of the skin of T. Franca and Sousão cultivars allowed to verify that the second had a higher percentage of extracts weight than the first cultivar, which may suggest some relation between this parameter and the observer attack. On the other hand, it was found that, in both cultivars, the infested berries have a higher percentage of weight of the extracts than noninfested ones.
The European Grape Moth (EGM), Lobesia botrana, is a key pest of the vine in the Douro Demarcated Region (DDR). The economic importance of this pest, together with the need to reduce the use of chemical insecticides has been of particular interest in the use of mating disruption (MD), which has been underway in the DDR since 2000, although with results that are not always satisfactory. In this way, through the analysis of data collected from 2000 to 2019, the influence of the grapevine cultivar, the year, the sub-region and the insect generation on EGM infestation. On the other hand, through the work carried out in 2019, four red grape cultivars with different levels of susceptibility to the attack of L. botrana (Touriga Franca, Tinta Barroca, Touriga Nacional and Sousão) were also evaluated, characteristics responsible for the differences in susceptibility, namely morphological characteristics of the inflorescences/bunches (hairiness, weight, length, width, compaction, volume and number of berries), the texture of the berries (resistance to perforation, compression and skin structure) and the quantification of the skin extracts (chemical analysis). The results show that the infestation of EGM varies according to: (1) the grapevine cultivar (T. Franca and Malvasia Fina, in the case of red and white respectively grape varieties tends to be the most infested cultivars); (2) the year (infestation is dependent on the climatic conditions of the year but, tendentially, has been decreasing over the years); and (3) the subregion (lower in the Douro Superior than in the Cima Corgo and Baixo Corgo). In the same sampling date, larvae from T. Franca were those that, in general, were in a more advanced larval instar. Of the analyzed factors, hairiness and early of the inflorescence seem to influence the first generation infestation, since the inflorescences of T. Franca showed more early and less pubescence. In the case of bunches, T. Franca presented the highest compaction index, which could justify the greater preference, frequently observed. T. Nacional (one of the least attacked grape varieties) presented the highest resistance to perforation. The analysis of the extracts of the skin of T. Franca and Sousão cultivars allowed to verify that the second had a higher percentage of extracts weight than the first cultivar, which may suggest some relation between this parameter and the observer attack. On the other hand, it was found that, in both cultivars, the infested berries have a higher percentage of weight of the extracts than noninfested ones.
Descrição
Dissertação de Mestrado em Engenharia Agronómica
Palavras-chave
castas , confusão sexual