RESUMO
ABSTRACT The present study was aimed to survey and identify the parasitoids associated to dipterous leafminers occurring on spontaneous growing plants in an organic citrus orchard and to verify if these parasitoid species are the same ones reported for the citrus leafminer (Phyllocnistis citrella).The work was carried out in Montenegro, state of Rio Grande do Sul, Brazil, in a Murcott orchard. Fortnightly samplings, from May/2003 to May/2004, were carried out. On each occasion, 60 sampling units were collected. Each sampling unit consisted of all leaves with mines contained in an area delimited by a 0.28 m2 frame, thrown in and between lines aside each one of 30 randomly selected trees. In the laboratory, the leaves were kept individually in Petri dishes until the emergence of parasitoids or flies. Fifteen species of hymenopterous were registered encompassing: Eulophidae (Closterocerus coffeellae Ihering, Closterocerus sp., Chrysocharis sp. 1, Chrysocharis sp. 2, Chrysocharis tristis Hansson, Chrysocharis vonones Walker and Neochrysocharis sp.); Braconidae (Opius sp. 1, Opius sp. 2, Opius sp. 3, Opius sp. 4, Opius sp. 5, Centistidea sp. 1 and Centistidea sp. 2) and Figitidae (Agrostocynips clavatus, Díaz). According to the results, some species registered in the study, of the genera Closterocerus, Chrysocharis and Neochrysocharis, are reported parasitizing P. citrella.
RESUMO Este trabalho teve como objetivos realizar o levantamento e a identificação dos parasitóides associados aos dípteros minadores presentes na vegetação de crescimento espontâneo, em pomar orgânico de citros, e verificar se estes parasitóides são os mesmos relatados para o minador-dasfolhas-dos-citros (Phyllocnistis citrella). O trabalho foi conduzido em Montenegro, RS, em um pomar de tangoreiro Murcott. Realizaram-se amostragens quinzenais, de maio de 2003 a maio de 2004, coletando-se em cada ocasião 60 unidades de amostra. Cada unidade era constituída de todas as folhas com minas contidas na área delimitada por um aro de 0,28 m2, que era jogado na linha e na entrelinha de 30 árvores sorteadas.No laboratório as folhas foram mantidas, individualmente, em placas de Petri até a emergência dos parasitóides ou das moscas. Foram registradas 15 espécies de microimenópteros: sete de Eulophidae (Closterocerus coffeellae Ihering, Closterocerus sp., Chrysocharis tristis Hansson, Chrysocharis vonones Walker, Chrysocharis sp. 1, Chrysocharis sp. 2 e Neochrysocharis sp.), sete de Braconidae (Opius sp. 1, Opius sp. 2, Opius sp. 3, Opius sp. 4, Opius sp. 5, Centistidea sp. 1, Centistidea sp. 2) e uma de Figitidae, (Agrostocynips clavatus, Díaz). De acordo com os resultados, verificou-se que algumas espécies registradas no estudo pertencentes aos gêneros Closterocerus, Chrysocharis e Neochrysocharis são relatadas como parasitóides de P. citrella.
RESUMO
ABSTRACT This study aimed to verify the association of the "citrus leafminer", Phyllocnistis citrella Stainton, 1856 (Lepidoptera: Gracillariidae) with other host plants that exist in organiccitrus orchard, in order to explain aspects of its survival out of the Citrus spp flush season , and also to undertake a survey of leafminers present in the orchard. The work was carried out in Montenegro, RS, in an organic orchard grown with the hybrid Murcott. Samplings were taken every other week, from May 2003 to May 2004,by collecting on each occasion all themined leaves found in an area delimited by a 0.28 m2 circle thrown in and between the rows of 30 randomly chosen trees. During the study, the presence of P. citrella was notreportedon spontaneous growing plants in the orchard, and clearly shows its preference for Citrus species. However, 15 species of Diptera leafminers and 15 species of host plants belonging to three botanical families were recorded.
RESUMO Este trabalho teve como objetivo verificar a associação do "minador-das-folhas-dos-citros", Phyllocnistis citrella Stainton, 1856 (Lepidoptera: Gracillariidae), com outras plantas hospedeiras, presentes em pomar de citros, a fim de esclarecer aspectos da sua sobrevivência fora dos fluxos de brotação de Citrus spp. e fazer um levantamento de insetos minadores que habitam o pomar. O trabalho foi conduzido em Montenegro, RS, em um pomar orgânico de tangoreiro Murcott. Realizaram-se amostragens quinzenais, de maio de 2003 a maio de 2004, coletando-se em cada ocasião, todas as folhas com minas, contidas na área delimitada por um aro de 0,28 m2, que era jogado nas linhas e nas entrelinhas de 30 árvores sorteadas. Durante o estudo, não foi registrada a presença de P. citrella nas plantas espontâneas do pomar, comprovando-se a sua preferência por espécies de Citrus. Entretanto, registraram-se 15 espécies de dípteros minadores e 15 espécies de plantas hospedeiras, distribuídas em três famílias.
RESUMO
This study aimed to identify and characterize the pathogens associated with symptoms similar to Phaeosphaeria leaf spot (PLS) of maize in different environmental conditions in Brazil. During the last decade, PLS became an important disease of maize in Brazil. However, doubt persists about the causal agent. Maize leaves with PLS-like lesions were collected from two locations (Cristalina, Goiás State [GO] and Vila Maria, Rio Grande do Sul State [RS]) in two growing seasons. Fungi associated with leaf lesions were isolated and cultured for taxonomic identification. Pathogenicity tests were carried out and the results indicated that three fungi (a Phyllosticta sp., Phoma sorghina, and a Sporormiella sp.) caused leaf spot similar to PLS on maize. The composition of pathogenic fungi in PLS-like lesions varied depending on locations and growing seasons. The fungi P. sorghina and a Phoma sp. (Plenodomus section) occurred in all environments, but the Sporormiella and Phyllosticta spp. were restricted to GO and RS, respectively. The results support the hypothesis that various pathogens are involved in PLS-like symptoms of maize and environmental conditions may influence the predominance of a specific agent.