Citrus Sudden Death Is Transmitted by Graft-Inoculation and Natural Transmission Is Prevented by Individual Insect-Proof Cages.

Citrus sudden death (CSD) transmission was studied by graft-inoculation and under natural conditions. Young sweet orange trees on Rangpur rootstock were used as indicator plants. They were examined regularly for one or two characteristic markers of CSD: (i) presence of a yellow-stained layer of thickened bark on the Rangpur rootstock, and (ii) infection with the CSD-associated marafivirus. Based on these two markers, transmission of CSD was obtained, not only when budwood for graft-inoculation was taken from symptomatic, sweet orange trees on Rangpur, but also when the budwood sources were asymptomatic sweet orange trees on Cleopatra mandarin, indicating that the latter trees are symptomless carriers of the CSD agent. For natural transmission, 80 young indicator plants were planted within a citrus plot severely affected by CSD. Individual insect-proof cages were built around 40 indicator plants, and the other 40 indicator plants remained uncaged. Only two of the 40 caged indicator plants were affected by CSD, whereas 17 uncaged indicator plants showed CSD symptoms and were infected with the marafivirus. An additional 12 uncaged indicator plants became severely affected with citrus variegated chlorosis and were removed. These results strongly suggest that under natural conditions, CSD is transmitted by an aerial vector, such as an insect, and that the cages protected the trees against infection by the vector.

Faunistic analysis of sharpshooters (Hemiptera: Auchenorrhyncha, Cicadellidae) in a 'Westin' sweet orange orchard.

The purpose of this study was to analyze sharpshooter fauna in a five-year-old 'Westin' sweet orange orchard. Yellow sticky traps were placed on the edge of a forest, and on the periphery and inside the citrus stand. The traps were evaluated fortnightly, for three years. The most frequent species were Acrogonia citrina Marucci & Cavichioli, Bucephalogonia xanthophis (Berg), and Oncometopia facialis (Signoret). B. xanthophis occurred more in the forest edge, especially on spring and winter. A. citrina occurred most frequently in the forest edge, especially on spring. The highest incidence of O. facialis was inside the citrus stand, on spring and summer. Other cicadellids occurred more often in the forest edge, especially on summer. A. citrina, B. xanthophis, Dilobopterus costalimai Young, and O. facialis were predominant in all places studied. A. citrina, B. xanthophis and O. facialis were super dominant, super abundant, super frequent, and constant, except inside the stand, where B. xanthophis was dominant, very abundant, very frequent, and constant. D. costalimai and Homalodisca ignorata Melichar were dominant, very abundant, and very frequent in the forest edge and in the periphery of the stand, and D. costalimai was also predominant inside the stand. Scopogonalia subolivacea (Stål) was predominant in the forest edge and inside the stand, while Plesiommata corniculata Young was predominant in the periphery (both were dominant, very abundant, very frequent, and accessory).

Faunistic analysis of sharpshooters (Hemiptera: Auchenorrhyncha, Cicadellidae) in a 'Westin' sweet orange orchard / Análise faunística de cicadelíneos (Hemiptera: Auchenorrhyncha, Cicadellidae) em pomar de laranjeira 'Westin'

The purpose of this study was to analyze sharpshooter fauna in a five-year-old 'Westin' sweet orange orchard. Yellow sticky traps were placed on the edge of a forest, and on the periphery and inside the citrus stand. The traps were evaluated fortnightly, for three years. The most frequent species were Acrogonia citrina Marucci & Cavichioli, Bucephalogonia xanthophis (Berg), and Oncometopia facialis (Signoret). B. xanthophis occurred more in the forest edge, especially on spring and winter. A. citrina occurred most frequently in the forest edge, especially on spring. The highest incidence of O. facialis was inside the citrus stand, on spring and summer. Other cicadellids occurred more often in the forest edge, especially on summer. A. citrina, B. xanthophis, Dilobopterus costalimai Young, and O. facialis were predominant in all places studied. A. citrina, B. xanthophis and O. facialis were super dominant, super abundant, super frequent, and constant, except inside the stand, where B. xanthophis was dominant, very abundant, very frequent, and constant. D. costalimai and Homalodisca ignorata Melichar were dominant, very abundant, and very frequent in the forest edge and in the periphery of the stand, and D. costalimai was also predominant inside the stand. Scopogonalia subolivacea (Stål) was predominant in the forest edge and inside the stand, while Plesiommata corniculata Young was predominant in the periphery (both were dominant, very abundant, very frequent, and accessory).

O objetivo deste trabalho foi analisar a fauna de cigarrinhas em pomar de laranjeira 'Westin' enxertada sobre limoeiro 'Cravo', em plantas com cinco anos de idade. Foram instaladas armadilhas adesivas amarelas na borda da mata, na periferia do talhão e no interior do talhão, sendo avaliadas quinzenalmente, por três anos. As cigarrinhas que ocorreram com maior freqüência foram Acrogonia citrina Marucci & Cavichioli, Bucephalogonia xanthophis (Berg) e Oncometopia facialis (Signoret). B. xanthophis ocorreu mais na borda da mata, principalmente na primavera e inverno. A. citrina ocorreu mais na borda da mata, principalmente na primavera. A a maior incidência de O. facialis foi no interior do talhão, e maior na primavera e verão. A ocorrência de outros cicadelíneos foi maior na borda da mata, principalmente no verão. Segundo a análise faunística, A. citrina, B. xanthophis, Dilobopterus costalimai Young e O. facialis foram predominantes em todos os locais estudados; A. citrina, B. xanthophis e O. facialis foram super dominantes, super abundantes, super freqüentes e constantes, exceto no interior do talhão, onde B. xanthophis foi dominante, muito abundante, muito freqüente e constante. D. costalimai e Homalodisca ignorata Melichar foram dominantes, muito abundantes e muito freqüentes na borda da mata e periferia do talhão, sendo que D. costalimai também foi predominante no interior do talhão. Scopogonalia subolivacea (Stål) foi predominante na borda da mata e interior do talhão e Plesiommata corniculata Young, na periferia do talhão (ambas foram dominantes, muito abundantes, muito freqüentes e acessórias).