Offering floral rewards to pollinators such as nectar and pollen may not mean reproductive success. Some plant species present strategies to minimize this cost and dupe their pollinators. Begonia cucullata presents a mimicry system characterized by female rewardless flowers (mimic) that mimic male flowers (model) with a large amount of pollen. For the perfect functioning of mimetism, the proportion of mimics should not be higher than models. We tested different arrays of mimic-model flower proportions to test the efficacy of this system. We observed that bees avoided rewardless female flowers, although fruit set did not indicate pollen limitation.

In plants pollinated by different groups of animals, the most frequent visitors may not be the most effective for fitness because of their differential efficiency in pollen transfer. We addressed this question by studying a rare dioecious species of Rubiaceae in Brazil. The flowers of Randia itatiaiae are gender-heteromorphic and hypocrateriform with greenish corolla tubes ~2 cm long, and exhale a strong sweet scent during the entire period of anthesis, which starts at sunset for female flowers. Sucrose was the dominant or co-dominant nectar sugar for both genders. In spite of these typical sphingophilous-phalaenophilous traits, the flowers last for 6 days, and nectar was available in both diurnal and nocturnal assessments. Moreover, the flowering of R. itatiaiae did not overlap the phenodynamics of the Sphingidae community. Accordingly, two functional groups of Lepidoptera – Hesperiidae during the day and Sphingidae and Noctuidae at night – visited the flowers. Visits by either group resulted in equivalent fruit set and seed number per fruit, although the frequency of visits to flowers was higher during the day than at night. Diurnal and nocturnal lepidopterans may exert similar pressures on floral morphology, in addition to divergent pressures on other characters, such as the temporal dynamics of anthesis and nectar production. The pollination system of R. itatiaiae is specialised at the coarse scale, because its floral morphology precludes pollination by animals other than lepidopterans; however, its floral phenotype also represents a generalist compromise between the conflicting pressures exerted by diurnal and nocturnal groups of lepidopterans.

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RESUMO Uma nova espécie de Rubiaceae para a Floresta Atlântica do estado do Rio de Janeiro é descrita e ilustrada baseada em recentes coleções procedentes do Parque Nacional do Itatiaia.

Diverse ecological factors (top-down and bottom-up) act on the richness and abundance patterns of insect galls. Host plant density is a kind of bottom-up factor and is related to ''resource concentration hypothesis.'' In this study, we analyzed forest patches that differ in vegetational structure and host plant abundance: homogeneous forest patches (Schinus-dominated) and more complex forest patches, to determine whether there are differences in the intensity of gall infestation among individual trees. Insect galls were sampled from 15 Schinus polygamus trees along five transects in each forest (150 trees in total). Two galler species, a psyllid leaf galler and cecidomyiid shoot galler, were recorded. We found that Psyllidae gall infestation in S. polygamus presents higher values of galls per individual tree in Schinus-dominated forest patches than forest patches that are more diverse in plant species. Cecidomyiidae galls did not differ between areas and were not related to host plant abundance. We did not observe any variation in gall infestation within individual. Our study demonstrated that density-dependence effect could be more important for some galls species than others. The results suggest that biological attributes of galling insects' infestation could be associated with susceptibility to host plant density.

-(Pollen types found on hawkmoths (lepidoptera, Sphingidae) in the atlantic Rain Forest area of Southeastern Brazil: use of palinology in studies of ecological interactions). the species of the plants used by a hawkmoth community (lepidoptera, Sphingidae) were recorded through pollen types collected on the bodies of specimens in an area of the atlantic Rain Forest of Southeastern Brazil. a total of 63 pollen types of 27 families were recorded, which showed assimetrical temporal distribution during the study. Species of Rubiaceae, Bromeliaceae and Fabaceae predominated in the records. the Inga pollen type was present in almost all the recorded months and in many of the hawkmoths species. Pollen types of species that did not present sphingophilous traits were the most common in the samples, a fact that could be related with the generalist foraging pattern of this group of lepidoptera. this study demonstrates the utility of palinology on ecological studies of plant-pollinator interactions in the tropics.Key words -generalist foraging, hawkmoth community, Inga, Rubiaceae RESUMO -(Tipos polínicos encontrados em esfingídeos (Lepidoptera, Sphingidae) em área de Floresta Atlântica do Sudeste do Brasil: uso da palinologia no estudo de interações ecológicas). Foram determinadas as espécies de plantas utilizadas por uma comunidade de esfingídeos (Lepidoptera, Sphingidae) através da avaliação dos tipos polínicos que os espécimes apresentavam sobre seus corpos, em uma área de Floresta Atlântica do Sudeste do Brasil. Foram registrados 63 tipos polínicos de 27 famílias distribuídos assimetricamente ao longo do ano. Houve predomínio de espécies de Rubiaceae, Bromeliaceae e Fabaceae. Pólen do tipo Inga esteve presente em quase todos os meses amostrados e em grande número de espécies de esfingídeos. Tipos polínicos relativos a famílias que não apresentam atributos morfológicos adaptativos ao uso por Sphingidae foram responsáveis pela maior parte das amostras, o que demonstra forte aspecto generalista no comportamento de forrageamento deste grupo de lepidópteros. este estudo reforça a utilidade do uso da palinologia no entendimento de padrões de interações inseto-planta em ambientes tropicais.Palavras-chave -comportamento generalista, comunidade de mariposas, Inga, Rubiaceae . Soma-se a isso, o fato de serem agentes polinizadores de numerosas espécies em ecossistemas tropicais (Bawa 1990(Bawa , oliveira 1991, tendo importante papel na estruturação e na dinâmica de populações vegetais. Esta função poderia ser avaliada e medida, por exemplo, pelo número de espécies vegetais que dependem do serviço de polinização deste grupo de insetos. Porém, esfingídeos apresentam comportamento quase exclusivamente noturno, o que torna a observação das visitas às flores bastante restrita e, consequentemente, a avaliação de sua importância no sistema é dificultada, baseando-se quase que totalmente em taxas de sucesso reprodutivo nas espécies que apresentam atributos de polinização por esfingídeos: flores de coloração branca, antese noturn...