Abstract Cereus jamacaru is a cactus distributed in Northeastern Brazil, with high symbolic value to this region. However, the interaction, behavior and the role of pollinators remains poorly understood. Here, we investigate the reproductive biology, addressing the ecological significance of floral attributes, including details about floral signaling. The study was carried at three areas of the Caatinga, in 2015, 2017 and 2021. We analyzed the floral morphometry, volume and concentration of the nectar, and characterized the colour and scent of flowers. Additionally, we described the pollinator behavior and performed controlled pollination experiments. The ‘Mandacaru’ is self-incompatible, has nocturnal anthesis and the nectar is accumulated as droplets in a long hypanthial tube. The flowers have a reflective pattern with a dark outer surface and a white inner surface. (E)-nerolidol is the major component (87.4%) of its floral perfume. We registered the sphingid moth Cocytius antaeus visiting the flowers. The floral attributes, attractants and rewards drives to a sphingophily, and the pollination treatments showed the dependence to fruit set by C. antaeus, the pollinator registered. In this case, if the apparent lack of pollinator diversity encompasses its entire range, the loss of the hawkmoth could severely impact the reproductive success of the cactus.

ABSTRACT Male euglossine bees (Euglossine: Apidae) pollinate flowers of as many as 1,000 Neotropical plant species and there is evidence that blooming in these plants is synchronized with the seasonality of euglossine pollinators. The present study aimed to monitor for two years the phenology of Sarcoglottis acaulis (Orchidaceae - Spiranthinae subtribe) and the seasonality of its pollinators at three Atlantic Forest fragments, two of which surrounded by urban anthropized areas. Phenologies in the three areas were related to abiotic factors, suggesting that precipitation on months prior to the beginning of the flowering period influenced the fructification rates of S. acaulis. Additionally, water shortage during the driest months resulted in vegetative dormancy. Sarcoglottis acaulis sets only a low number of fruits by self-pollination, and the plant’s reproductive success depended on the frequency of its main pollinator, i.e., the male euglossine bees Eulaema atleticana. Lower rates of pollinia removal were observed in areas where this bee is less frequent and, consequently, less fruits were formed, suggesting a high dependency on this pollinator.

O Agreste é uma região de transição entre floresta tropical úmida e caatinga no nordeste brasileiro. Nessa região, grande parte da vegetação nativa foi desmatada para a implantação de pastagens. Não é sabido se áreas degradadas mantém uma apifauna e flora melitófila diversificada, ou quais são associações entre abelhas e plantas que ocorrem nessas áreas. A cobertura vegetal atual é composta por pastos, vegetação ruderal e restos da vegetação nativa. Abelhas e plantas por elas visitadas foram coletadas mensalmente entre agosto de 2001 e julho de 2002, durante dois dias consecutivos entre 5h30 e 17h30. Foram coletados 1.004 indivíduos de abelhas pertencentes a 79 espécies. Apidae foi a família mais abundante e com maior riqueza de espécies (732 indivíduos e 43 espécies), seguida por Halictidae (194 indivíduos e 20 spp.), Megachilidae (47 indivíduos e 13 spp.), Colletidae (16 indivíduos e 2 spp.) e Andrenidae (15 indivíduos e 1 sp.). Foram registradas apenas três espécies de abelhas eussocais e cinco de Euglossini, dois grupos altamente diversificados nas florestas neotropicais. A ausência de abelhas sem ferrão nativas dos gêneros Plebeia, Frieseomelitta, Partamona, Scaptotrigona e Trigonisca, assim como de outras espécies de Euglossini, deve estar relacionada à falta de sítios de nidificação e à escassez de fontes de pólen e néctar nessa área degradada. Foram registradas 87 espécies de plantas melitófilas, a maioria ervas e arbustos. Árvores nativas isoladas, assim como plantas ornamentais e frutíferas cultivadas contribuem para manter parte da diversidade da comunidade de abelhas nativas.

The Agreste is a transition region of tropical rainforest and Caatinga in northeastern Brazil. In this region, the majority of the native Atlantic Rainforest was destroyed to give place to livestock farming. It is not known whether degraded areas maintain a diversified bee-plant community or not and which kinds of bee-plant interactions occur. The vegetation at the study site comprises pastures, ruderal vegetation and minute remanents of rainforest vegetation. Both bees and associated plants were collected monthly, from August 2001 to July 2002, sampling during two consecutive days from 5:30 am to 5:30 pm. We collected a total of 1004 bees from 79 species. Apidae was the most abundant and species-rich bee family (732 individuals, 43 species) followed by Halictidae (194 individuals and 20 spp.), Megachilidae (47 individuals and 13 spp.), Colletidae (16 individuals and 2 spp.) and Andrenidae (15 individuals and 1 sp.). Only three species of eusocial bees and five of euglossine bees were recorded, even though both groups are diversified in Neotropical rainforests. The absence of native stingless bees of the genera Plebeia, Frieseomelitta, Partamona, Scaptotrigona and Trigonisca, as well as of other euglossine bee species, is probably due to the lack of nesting sites and to the paucity of pollen and nectar resources in this disturbed area. The bees visited flowers of 87 plant species, mainly of herbs and small shrubs. Isolated rainforest trees in the pasture as well as cultivated fruit crops contributed to some extent to maintain a diversified native bee community.

Abelhas Euglossini são conhecidas por serem polinizadores de longas distâncias em florestas tropicais. No entanto, existem controvérsias sobre o raio de vôo dessas abelhas entre fragmentos florestais. Em um fragmento isolado de Mata Atlântica, cercado por monoculturas de cana-de-açúcar, em Pernambuco, Nordeste brasileiro, foi examinado se os machos de Euglossini deixam a mata para coletar fragrâncias. Machos de Euglossini foram capturados simultaneamente por iscas odoríferas ao longo de um transecto em sete pontos: interior da mata, borda da mata e no canavial, a distâncias de 10 m, 50 m, 100 m, 250 m e 500 m da borda. Foram registrados 945 indivíduos de Euglossini pertencentes a 16 espécies. Os resultados mostram diferentes relações das espécies de Euglossini com a floresta fechada. Machos de 11 espécies não saíram da mata. Essas espécies, juntamente com suas plantas relacionadas, parecem ser as mais ameaçadas pela fragmentação do habitat. Apenas abelhas de cinco espécies foram encontradas em iscas odoríferas no canavial. Além do mais, o ponto de amostragem de 10 m fora da mata mostrou uma acentuada redução na riqueza de espécies, indicando que a borda da mata é uma barreira para a maioria das espécies de Euglossini.

Euglossine bees are known to be long-distance pollinators in tropical rainforests. But there is controversy concerning to the flight ranges of these bees between forest fragments. In an isolated fragment of Atlantic Rainforest in Pernambuco, NE Brazil, surrounded by sugarcane monocultures, it was examined if euglossine males leave closed rainforest to collect fragrances. In a straight-line transect leading from forest into a sugarcane plantation, euglossine males were simultaneously captured by scent baits at seven distinct points: inside the forest, forest edge, outside the forest in the sugarcane fields at distances of 10 m, 50 m, 100 m, 250 m and 500 m from the forest edge. A total of 945 euglossine bees of 16 species were recorded. The results demonstrate different relations of the Euglossini species to the closed forest. Males of 11 species did not leave the forest. Such species, together with the plants they are linked to, seem to be the most threatened by habitat fragmentation. Only bees of five species were found at the scent baits in the sugarcane fields. Already the 10 m sampling point outside the forest showed a drastic reduction in species richness, indicating that the forest edge functions as a barrier for most euglossine species.