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As cochonilhas-algodão da vinha (Hemiptera: Pseudococcidae) na região do Oeste
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Resumo(s)
Mealybugs are major pests in many grapevine-growing regions in the world, including
Mediterranean countries, South Africa and California. The damage caused by mealybugs is
linked to sap uptake, honeydew secretion and associated sooty mold development, toxin
injection and virus transmission, such as Grapevine Leaf Roll associated Virus-3.
In this study we aimed at evaluating the pest-status of mealybugs on vineyards in the Oeste
region of Portugal, identifying mealybug species and estimating their infestation level.
Therefore, a survey was carried out in 71 grapevine plots, mainly at the counties of Alenquer,
Arruda dos Vinhos and Torres Vedras. In the infested plots, samples of adult mealybug
females were collected and preserved in 4 parts of 95% alcohol + 1 part of acetic acid for
slide mounting and species identification. Information on pest history of mealybugs, possible
factors involved on mealybug pest status, as well as on the adopted management strategies
was obtained based a questionnaire answered by the farmers or technical managers. All
sampled plots were qualitatively evaluated regarding the infestation level of mealybugs,
using the following notation: 0 - No detected mealybugs; 1 – Low infestation level; 2 –
Moderate infestation level; or 3 – High infestation level. A quantitative estimation of the
infestation level was performed in eight selected grapevine plots.
Mealybugs were detected on 76% of the sampled plots. Two mealybug species were
identified: Planococcus ficus (Signoret) and Pseudococcus viburni (Signoret), in 36 and 22
plots, respectively. Both species were associated only in five plots. Planococcus ficus was
the most frequent mealybug species in Alenquer and Arruda counties. On the other hand,
Pseudococcus viburni was most frequent in Torres Vedras.
About 38% of the farmers carried out at least one insecticide treatment to control mealybugs.
Chlorpyriphos was the most used active ingredient. No apparent relationship was observed
between grapevine varieties and crop susceptibility to mealybugs. Although, mealybug
outbreaks have been more commonly associated with older vineyards, we observed several
cases of very young grapevine plots with high levels of mealybug infestation. Possible
causes are discussed.
Low, moderate and high levels of mealybug infestation were recorded in 51%, 17% e 7% of
the plots, respectively. The infestation level in the eight plots studied ranged between 2,2%
and 39,9%. The infested plants, within each vine plot, showed a clumped pattern of spatial distribution.----------------------------Este estudo teve como objectivo avaliar a importância relativa das cochonilhas-algodão (CA)
da vinha em 3 concelhos da região do Oeste, esclarecer a identidade das espécies
existentes e estimar a respectiva intensidade de ataque. Para o efeito, foi realizada uma
prospecção, em 71 parcelas, sobretudo, nos concelhos de Alenquer, Arruda dos Vinhos e
Torres Vedras. Para além da recolha de amostras, para posterior identificação específica, foi
efectuado um inquérito aos proprietários ou aos técnicos das explorações agrícolas, para
conhecer o historial dos ataques e respectiva importância, eventuais factores de nocividade,
bem como as estratégias de protecção adoptadas. A intensidade de ataque foi estimada
qualitativamente em todas as parcelas, tendo-se procedido à estimativa quantitativa em oito
parcelas. As CA foram detectadas em 76% das parcelas, tendo-se identificado as espécies
Planococcus ficus (Signoret) e Pseudococcus viburni (Signoret), em 36 e 22 parcelas,
respectivamente. Cerca de 38% dos inquiridos efectuaram, pelos, menos um tratamento
insecticida contra CA, tendo o clorpirifos sido a substância activa mais utilizada. Registaramse
ataques fracos, moderados e fortes de CA, em 51%, 17% e 7% das parcelas,
respectivamente. A intensidade de ataque nas oito parcelas variou entre 2,2% e 39,9%. As
cepas infestadas, dentro de cada parcela, apresentaram padrão de distribuição agregado.
Descrição
Mestrado em Engenharia Agronómica - Protecção de Plantas - Instituto Superior de Agronomia
Palavras-chave
Planococcus ficus Pseudococcus viburni mealybugs vineyard cochonilha-algodão vinha Região do Oeste Portugal