1992). Host specicity and seed dispersal of Psittacanthus robustus (Loranthaceae) in south-east Brazil.ABSTRACT. Psillacanlhus robuslus (Loranthaceae) is a Neotropical mistletoe which grows mainly on species of Vochysiaceae in Brazilian 'cerrado' regions. Its parasitizing pattern involves: (a) the height and the aspect of the crown of the host-plants; (b) the presence of sticky substance in the fruits of the parasite; and (c) the feeding behaviour and habitat selection of the dispersal agent, the swallowtanager Tersina viridis viridis. The feeding behaviour of this bird on fruits of P. robustus facilitates seed release and seedling establishment; its foraging habit and habitat selection account for high concentrations of the parasites on their preferred host-plants. RESUMO. Psittacanthus robustus (Loranthaceae) e uma erva-de-passarinho neotropical que parasita principalmente especics de Vochysiaceae em cerrados brasileiros. O padrao de parasitismo tem relacao com: (a) a altura e o aspecto da copa das plantas hospedeiras; (b) a presence de substancia viscosa no fruto da parasita; e (t) o comportamento alimentar e a selec,ao de habitat do agente dispersor, o sai-andorinha Tersina viridis viridis. Seu comportamento alimentar facilita a liberac.ao da semente e o estabelccimcnto da plantula; seu habito de forrageamento e selec.ao de habitat ocasionam alta concentrac.ao de parasitas nas suas plantas hospedeiras principais.

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The yeast communities from necrotic tissues, decaying flowers and fruits, and from larval feeding sites of the moth Sigelgaita sp. in the cactus Pilosocereus arrabidae were surveyed in three restinga ecosystems in Southeastern Brazil. Insects associated with these substrates were sampled to verify the vectoring of yeasts. The cactus Pilosocereus arrabidae was shown to have four different yeast communities associated with it. Necrotic stems had a diverse yeast community with the prevalent species Pichia barkeri, Candida sonorensis, Pichia cactophila, Geotrichum sp., Myxozyma mucilagina and Sporopachydermia sp. A, representing about 80% of the total isolates. Pichia sp. A and a Candida domercqii-like species represented more than 90% of the yeast isolates from decaying flowers. Fruits had a heterogeneous yeast community with typical fruit yeasts of the genus Kloeckera, basidiomicetous anamorphs of the genus Cryptococcus, the black yeast Aureobasidium pullulans, Pichia sp. A, a Candida domercqii-like species, and some cactophilic yeasts, especially Clavispora opuntiae. The feeding site of Sigelgaita sp. larvae had Clavispora opuntiae as the prevalent species. Insect vectors are suggested as one the most important factors influencing the composition of these yeast communities.

ABSTRACT. Gall-forming species (Diptera, Cecidomyiidae) and parasitoids (Hymenoptera) associated with Guapira opposita (Vell.) Reitz. (Nyctaginaceae) at Restinga of Barra de Marid, Rio de Janeiro. Three different galls of Bruggmannia spp. (Diptera, Cecidomyiidae) on Guapira opposita (Vell.) Reitz. (Nyctaginaceae) were studied at Restinga ofBarra de Maricá, State ofRio de Janeiro. Thirty parasitoid species are associated to these galls. Most ofthem is generalist and solitary. Hyperparasitoidism is common. The trophic relations among gall makers and parasitoids are presented.