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A cochonilha-negra, Saissetia oleae (Olivier) (Hemiptera: Coccidae), Ă© uma praga importante da oliveira. Este fitĂłfago Ă© atacado por diferentes espĂ©cies de parasitoides cuja ação, em muitos casos, Ă© suficiente para manter as populaçÔes de cochonilha considerados tolerĂĄveis. Com o presente trabalho pretendeu-se estudar as populaçÔes de cochonilha-negra em oliveira na regiĂŁo de TrĂĄs-os-Montes em diferentes perĂodos do ano; avaliar a diversidade de parasitoides associado a esta praga e sua relação com os diferentes estados de desenvolvimento do hospedeiro e perĂodo do ano; e por Ășltimo procurar perceber a existĂȘncia da relação entre o estado de desenvolvimento do hospedeiro, seus parĂąmetros biomĂ©tricos e o parasitismo exercido.
Neste contexto, em 40 olivais da regiĂŁo de TrĂĄs-os-Montes foram feitas amostragem em quatro perĂodos distintos (julho, setembro e novembro de 2011 e maio de 2012). Em cada olival foram amostradas 10 oliveiras, colhendo-se 20 folhas infestadas de cochonilha-negra/ĂĄrvore. No laboratĂłrio, as folhas foram observadas, Ă lupa binocular, registado o nĂșmero de exemplares em cada estado desenvolvimento da praga, a distribuição na folha (pĂĄgina superior ou inferior) e colocadas em tubos de ensaio que foram selados e colocados em condiçÔes controladas (22ÂșC, 70%HR, 16L:8D) atĂ© emergĂȘncia de eventuais parasitoides. Os parasitoides emergidos foram identificados e procedeu-se Ă anĂĄlise dos parĂąmetros biomĂ©tricos do hospedeiro (comprimento, altura).
Os resultados obtidos mostraram que foi na amostragem de verĂŁo (julho) onde se observou maiores nĂșmeros de indivĂduos de cochonilha-negra, sendo na sua maioria ninfas do primeiro instar (aproximadamente 92% dos exemplares observados), que preferiam a pĂĄgina inferior da folha do hospedeiro. Foram identificadas sete espĂ©cies de parasitoides, designadamente Coccophagus lycimnia (Walker), C. semicircularis (Förster), Metaphycus flavus (Howard), M. helvolus (Compere), M. lounsburyi (Howard), Scutellista nigra (Fonscolombe), e S. caerulea (Merter) que e atuam de forma diferenciada de acordo com o estado de desenvolvimento do hospedeiro e a Ă©poca do ano. C. lycimnia foi a espĂ©cie mais abundante e a que originou maiores taxas de parasitismo, principalmente nas ninfas do terceiro instar. As taxas de parasitismo nos diferentes perĂodos de amostragem oscilaram entre 3,61 e os 23,54%. Verificou-se tambĂ©m que o tamanho do hospedeiro influencia a escolha do parasitoide, sendo que os parasitoides do gĂ©nero Coccophagus que parasitam ninfas do segundo e terceiro instar preferiam hospedeiros com tamanhos superiores aos hospedeiros atacados pelos parasitoides do gĂ©nero Metaphycus
Black scale, Saissetia oleae (Olivier) (Hemiptera: Coccidae), is an important pest of the olive tree. This pest is attacked by different species of parasitoids that in many cases, are sufficient to limit their populations. This work aims to study the black scale population in olive trees in TrĂĄs-os-Montes region in different periods of year, evaluated the parasitoids diversity associated with this pest and their relationship with the different development stages of host and period of year, and finally seek to realize the existence of the relationship between the development state of the host, their biometric parameters and parasitism exercised. In this context, in 40 olive groves in TrĂĄs-os-Montes region were made samples at four different times (July, September and November 2011 and May 2012). In each olive grove were sampled 10 olive trees and were collected 20 infested olive leaves by black scale per tree. In laboratory, leaves were observed by binocular microscope, recorded the number of individuals in each development stage of the pest, the distribution in leaf (page up or down) and placed in sealed test tubes under controlled conditions (22ÂșC, 70%HR, 16L:8D) until eventual parasitoid emergency. Parasitoids were identified and having proceeded to the analysis of the host biometric parameters (length, height). Results showed that it was in summer sample (July) where were observed the higher number of individuals of black scale, being mostly first instar nymphs (approximately 92 % of the individuals observed), that preferred the up page of the leaf. Were identified seven species of parasitoids namely Coccophagus lycimnia (Walker), C. semicircularis (Förster), Metaphycus flavus (Howard), M. helvolus (Compere), M. lounsburyi (Howard), Scutellista nigra (Fonscolombe), and S. caerulea (Merter) that act differently according the host stage development and season of the year. C. lycimnia was the most abundant species that originated the higher rates of parasitism, especially in nymphs of the third instar. Parasitism rates in different sampling periods ranged between 3.61 to 23.54%. It was also found that the size of the host influences the choice of the parasitoid, being the parasitoids of the genus Coccophagus that parasitize second and third instar nymphs preferred hosts with larger sizes than the hosts attacked by parasitoids of the genus Metaphycus.
Black scale, Saissetia oleae (Olivier) (Hemiptera: Coccidae), is an important pest of the olive tree. This pest is attacked by different species of parasitoids that in many cases, are sufficient to limit their populations. This work aims to study the black scale population in olive trees in TrĂĄs-os-Montes region in different periods of year, evaluated the parasitoids diversity associated with this pest and their relationship with the different development stages of host and period of year, and finally seek to realize the existence of the relationship between the development state of the host, their biometric parameters and parasitism exercised. In this context, in 40 olive groves in TrĂĄs-os-Montes region were made samples at four different times (July, September and November 2011 and May 2012). In each olive grove were sampled 10 olive trees and were collected 20 infested olive leaves by black scale per tree. In laboratory, leaves were observed by binocular microscope, recorded the number of individuals in each development stage of the pest, the distribution in leaf (page up or down) and placed in sealed test tubes under controlled conditions (22ÂșC, 70%HR, 16L:8D) until eventual parasitoid emergency. Parasitoids were identified and having proceeded to the analysis of the host biometric parameters (length, height). Results showed that it was in summer sample (July) where were observed the higher number of individuals of black scale, being mostly first instar nymphs (approximately 92 % of the individuals observed), that preferred the up page of the leaf. Were identified seven species of parasitoids namely Coccophagus lycimnia (Walker), C. semicircularis (Förster), Metaphycus flavus (Howard), M. helvolus (Compere), M. lounsburyi (Howard), Scutellista nigra (Fonscolombe), and S. caerulea (Merter) that act differently according the host stage development and season of the year. C. lycimnia was the most abundant species that originated the higher rates of parasitism, especially in nymphs of the third instar. Parasitism rates in different sampling periods ranged between 3.61 to 23.54%. It was also found that the size of the host influences the choice of the parasitoid, being the parasitoids of the genus Coccophagus that parasitize second and third instar nymphs preferred hosts with larger sizes than the hosts attacked by parasitoids of the genus Metaphycus.
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Keywords
Cochonilha-negra Parasitismo Coccophagus lycimnia Parùmetros biométricos