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Abstract The present study describes the behavior of male Emphorini bees in exploiting Convolvulaceae flowers as sleeping-sheltering place. The observations occurred inadvertently during a field study in an Agroforestry System in the Caatinga region, near the banks of the São Francisco River in Petrolina, Pernambuco - NE-Brazil. Males were observed and collected in wilted flowers of Ipomoea carnea (Convolvulaceae) during the evening. The sampling revealed nine Emphorini bees, belonging to three oligolectic species specialized on Convolvulaceae. We propose that the infundibuliform morphology of Ipomoea carnea flowers and the varied timing of anthesis could influence the choice of these flowers as overnight resting places. Furthermore, we endorse the idea present in the literature that males of oligolectic bees generally engage in patrolling flowers utilized by females, thereby enhancing the chances of encountering potential mates, making these flowers rendezvous places. The observation of this behavior highlights the interdependence between bees and plants and raises the possibility that the loss of these flowers could negatively impact bees not only in a nutrition aspect but also regarding shelter and reproduction.
Resumo O presente estudo documenta o comportamento de abelhas machos do grupo Emphorini em explorar flores da família Convolvulaceae como local para dormir e se abrigar. As observações foram realizadas inadvertidamente durante um estudo de campo em um Sistema Agroflorestal na região da Caatinga, próximo às margens do Rio São Francisco, em Petrolina, Pernambuco - Nordeste do Brasil. Machos foram observados e coletados em flores fechadas de Ipomoea carnea (Convolvulaceae) durante o entardecer. Em nossa amostragem, encontramos nove machos da tribo Emphorini, pertencentes a três espécies oligoléticas especializadas em Convolvulaceae. Propomos que a morfologia infundibuliforme das flores de Ipomoea carnea e os diferentes períodos de antese das flores podem influenciar a escolha dessas flores como locais de descanso durante à noite. Além disso, nossos dados endossam a ideia de que machos de abelhas oligoléticas geralmente patrulham flores utilizadas por fêmeas, aumentando assim as chances de encontrar possíveis parceiras, tornando essas flores locais de encontro para acasalamento. O registro desse comportamento destaca a interdependência entre abelhas e plantas e levanta a possibilidade de que a perda dessas flores possa impactar negativamente as abelhas não apenas em relação a sua nutrição, mas também em relação ao abrigo e reprodução.
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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.
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Cactaceae , Brasil , Bosques , Néctar de las PlantasRESUMEN
BACKGROUND AND AIMS: Eriocaulaceae exhibit a great variety of floral traits associated with insect (e.g. nectariferous structures) and wind pollination (unisexual flowers, exposed sexual organs and small pollen grains), as well as the 'selfing syndrome' (small flowers, short distance between stigma and anthers, and temporal overlap of male and female phases). Paepalanthus bifidus, P. subtilis and P. tortilis are related species that differ in form, size and colour of floral structures. We aimed to investigate the pollination and reproductive biology of these three species. METHODS: We analysed the floral biology, floral visitors, pollinator behaviour, and the contribution of insects, wind and spontaneous geitonogamy to fruit set. We also evaluated the floral colour and scent of the species. Colour reflectance of capitula of each species was measured and plotted in models of insect vision. Floral scent samples were extracted and the compounds were compared to vegetative scent samples. KEY RESULTS: In all species, the staminate and pistillate flowers are arranged in alternating cycles with a temporal overlap between these phases. Ants were the most frequent floral visitors and were effective pollinators in P. bifidus and P. tortilis, while flies were occasional pollinators in P. tortilis. Floral visitors were not observed in P. subtilis. In all species, fruits were produced by spontaneous geitonogamy, with no evidence of wind pollination. According to the models of insect vision, the colours of the capitula of P. bifidus and P. subtilis are the most inconspicuous for ants and flies. We found no difference between the emission of volatiles of inflorescences and vegetative structures. CONCLUSIONS: This study suggests that ant pollination might be more widespread in Eriocaulaceae than currently assumed. Furthermore, for small monocarpic plants, mixed mating strategies are most favourable, by ensuring reproduction either by outcrossing when pollinators are abundant or by spontaneous geitonogamy when pollinations are scarce/absent.
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Hormigas , Eriocaulaceae , Animales , Flores/química , Insectos , Polinización , ReproducciónRESUMEN
Catasetum is a speciose Neotropical orchid genus of which male and female flowers emit scents acting both as attractant and reward for their exclusive pollinators, male orchid bees (Euglossini: Apidae). In Catasetum, it is well known that flowers display a remarkably morphological sexual dimorphism. However, it remains poorly investigated whether this is also true for floral scents. Here, we investigated the pollination ecology and floral scent traits (chemistry and total emission) of C. maranhense, a species endemic to the Brazilian N/NE region. Males of Euglossa securigera are the only pollinators of C. maranhense. The floral scent of C. maranhense is composed of 29 volatile compounds, with eucalyptol, indole, (E)-Methyl p-methoxycinnamate, and (Z)-Methyl p-methoxycinnamate accounting for more than 80% of the scent bouquet. No sexual dimorphism was detected in any of the traits investigated. We discuss the ecological and evolutionary significance of our findings to Catasetum species and other unisexual perfume plants.
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The study of insect semiochemicals, especially pheromones, is of fundamental importance for the development of strategies for controlling agricultural pests. In this study, volatile compounds involved in the communication between males and females of the fruit fly, Anastrepha obliqua (Diptera: Tephritidae), for mating purposes were characterized to develop attractant formulations for females of this species. Extracts containing volatile compounds released by males of A. obliqua were obtained by the dynamic headspace technique and analyzed by gas chromatography coupled with an electroantennographic detector (GC-EAD) and gas chromatography coupled with mass spectrometry (GC-MS). Twenty-one volatile compounds were identified in the aeration extracts of males. Five of them caused EAD responses from the antennae of females: 1-heptanol, linalool, (Z)-3-nonen-1-ol, (E,Z)-3,6-nonadien-1-ol, and (Z,E)-α-farnesene. Six synthetic mixtures of these compounds, including the five-component blend and all possible four-component blends, were formulated in a biopolymer and used in behavioral bioassays conducted in the laboratory arena with conspecific virgin females. One blend of 1-heptanol, linalool, (Z)-3-nonen-1-ol, and (Z,E)-α-farnesene attracted more females than the collection of volatiles from virgin males used as control. The other mixtures were as attractive to A. obliqua females as the control treatment. This study indicates potential for use of these compounds in monitoring and control strategies for this pest.
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Monoterpenos Acíclicos/aislamiento & purificación , Heptanol/aislamiento & purificación , Sesquiterpenos/aislamiento & purificación , Atractivos Sexuales/fisiología , Tephritidae/fisiología , Animales , Antenas de Artrópodos/fisiología , Femenino , Cromatografía de Gases y Espectrometría de Masas , Masculino , Atractivos Sexuales/química , Tephritidae/químicaRESUMEN
Dengue fever has spread worldwide and affects millions of people every year in tropical and subtropical regions of Africa, Asia, Europe and America. Since there is no effective vaccine against the dengue virus, prevention of disease transmission depends entirely on regulating the vector (Aedes aegypti) or interrupting human-vector contact. The aim of this study was to assess the oviposition deterrent activity of essential oils of three cultivars of torch ginger (Etlingera elatior, Zingiberaceae) against the dengue mosquito. Analysis of the oils by gas chromatography (GC)-mass spectrometry revealed the presence of 43 constituents, of which α-pinene, dodecanal and n-dodecanol were the major components in all cultivars. Solutions containing 100 ppm of the oils exhibited oviposition deterrent activities against gravid Ae. aegypti females. GC analysis with electroantennographic detection indicated that the oil constituents n-decanol, 2-undecanone, undecanal, dodecanal, trans-caryophyllene, (E)-ß-farnesene, α-humulene, n-dodecanol, isodaucene and dodecanoic acid were able to trigger antennal depolarization in Ae. aegypti females. Bioassays confirmed that solutions containing 50 ppm of n-dodecanol or dodecanal exhibited oviposition deterrent activities, while a solution containing the alcohol and aldehyde in admixture at concentrations representative of the oil presented an activity similar to that of the 100 ppm oil solution. Docking and molecular dynamics simulations verified that the interaction energies of the long-chain oil components and Ae. aegypti odorant binding protein 1 were quite favorable, indicating that the protein is a possible oviposition deterrent receptor in the antenna of Ae. aegypti.
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Aedes/efectos de los fármacos , Conducta Animal/efectos de los fármacos , Fenómenos Electrofisiológicos/efectos de los fármacos , Flores/química , Simulación de Dinámica Molecular , Aceites Volátiles/farmacología , Zingiberaceae/química , Aedes/metabolismo , Aedes/fisiología , Animales , Antenas de Artrópodos/efectos de los fármacos , Antenas de Artrópodos/fisiología , Dengue/transmisión , Femenino , Humanos , Proteínas de Insectos/química , Proteínas de Insectos/metabolismo , Insectos Vectores/efectos de los fármacos , Insectos Vectores/metabolismo , Insectos Vectores/fisiología , Aceites Volátiles/química , Aceites Volátiles/metabolismo , Conformación ProteicaRESUMEN
Aedes aegypti is responsible for the transmission of dengue, a disease that infects millions of people each year. Although essential oils are well recognized as sources of compounds with repellent and larvicidal activities against the dengue mosquito, much less is known about their oviposition deterrent effects. Commiphora leptophloeos, a tree native to South America, has important pharmacological properties, but the chemical profile and applicability of its essential oil in controlling the spread of the dengue mosquito have not been investigated. The aim of this study was to determine the composition of C. leptophloeos leaf oil and to evaluate its larvicidal and oviposition deterrent effects against A. aegypti. Fifty-five components of the essential oil were detected by gas chromatography (GC)-mass spectrometry, with α-phellandrene (26.3%), (E)-caryophyllene (18.0%) and ß-phellandrene (12.9%) identified as the major constituents. Bioassays showed that the oil exhibited strong oviposition deterrent effects against A. aegypti at concentrations between 25 and 100 ppm, and possessed good larvicidal activity (LC50 = 99.4 ppm). Analysis of the oil by GC coupled with electroantennographic detection established that seven constituents could trigger antennal depolarization in A. aegypti gravid females. Two of these components, namely (E)-caryophyllene and α-humulene, were present in substantial proportions in the oil, and oviposition deterrence assays confirmed that both were significantly active at concentrations equivalent to those present in the oil. It is concluded that these sesquiterpenes are responsible, at least in part, for the deterrent effect of the oil. The oviposition deterrent activity of the leaf oil of C. leptophloeos is one of the most potent reported so far, suggesting that it could represent an interesting alternative to synthetic insecticides. The results of this study highlight the importance of integrating chemical and electrophysiological methods for screening natural compounds for their potential in combating vectors of insect-borne diseases.
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Aedes/efectos de los fármacos , Commiphora/química , Aceites Volátiles/farmacología , Oviposición/efectos de los fármacos , Hojas de la Planta/química , Sesquiterpenos/farmacología , Aedes/fisiología , Animales , Antiinflamatorios no Esteroideos/farmacología , Electrofisiología/métodos , Femenino , Cromatografía de Gases y Espectrometría de Masas/métodos , Sesquiterpenos Monocíclicos , Aceites Volátiles/química , Sesquiterpenos PolicíclicosRESUMEN
Catasetum is a neotropical orchid genus that comprises about 160 dioecious species with a remarkable sexual dimorphism in floral morphology. Flowers of Catasetum produce perfumes as rewards, which are collected only by male euglossine bees. Currently, floral scents are known to be involved in the selective attraction of specific euglossine species. However, sexual dimorphism in floral scent and its eventual role in the pollination of Catasetum species have never been investigated. Here, we have investigated the pollination of Catasetum uncatum and asked: (1) Is floral scent a sexual dimorphic trait? (2) Does pollinarium removal/deposition affect scent emission? (3) Does sexual dimorphism in floral scent and changed scent emission have implications with regard to the behaviour of the pollinators? The frequency and behaviour of floral visitors were observed in non-manipulated flowers (both flower sexes) and in manipulated flowers (pistillate only) in which pollinaria were deposited. Scents of staminate and pistillate flowers (both manipulated and non-manipulated) were collected by using dynamic headspace methods and analysed chemically. Electrophysiological analyses were performed to detect compounds triggering antennal depolarisation in the euglossine species. C. uncatum is pollinated mainly by males of Euglossa nanomelanotricha. Pollinators were more frequent in pistillate than in staminate inflorescences. Bees approaching staminate flowers frequently flew away without visiting them, a behavioural pattern not observed in pistillate flowers. In the chemical analyses, we recorded 99 compounds, 31 of which triggered antennal depolarisation in pollinators. Multivariate analyses with the electrophysiological-active compounds did not detect differences between the scent composition of staminate and pistillate flowers. Pollinarium removal or deposition resulted in diminished scent emission within 24h in staminate and pistillate flowers, respectively. Surprisingly, bees discriminated pollinated from non-pollinated pistillate flowers as early as 2h after pollination. The rapid loss in the attractiveness of flowers following pollinarium removal/deposition can be interpreted as a strategy to direct pollinators to non-pollinated flowers. We have found no evidence that euglossine males discriminate staminate from pistillate flowers by means of floral scent. Instead, we speculate that bees use visual cues, such as sex dimorphic traits, to discriminate flowers of different sexes. Together, our results provide interesting insights into the evolution of floral signals in gender-dimorphic species and into its significance in plant reproductive biology.
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Abejas , Orchidaceae/química , Polinización/fisiología , Terpenos/química , Terpenos/aislamiento & purificación , Compuestos Orgánicos Volátiles/análisis , Animales , Brasil , Flores/química , Masculino , Estructura Molecular , Perfumes/análisis , Compuestos Orgánicos Volátiles/químicaRESUMEN
BACKGROUND AND AIMS: The close relationship between distylic Cordia leucocephala and the bee Ceblurgus longipalpis, both endemic to the Caatinga, north-east Brazil, was investigated, emphasizing reproductive dependence, morphological adaptations of the partners, and pollen flow. METHODS: In the municipality of Pedra, in the Caatinga of Pernambuco, the breeding system and reproductive success of C. leucocephala, its interaction with flower visitors and inter- and intramorph pollen flow were determined. KEY RESULTS: The bee Ceblurgus longipalpis, the unique flower visitor and effective pollinator of self-incompatible Cordia leucocephala, presents morphological features adapted to exploit hidden pollen and nectar in the long and narrow corolla tubes. Pollen of low-level anthers is collected with hairs on prolonged mouthparts and pollen of high-level anthers with clypeus, mandibles, and labrum, showing pollen removal from both levels with the same effectiveness. In both morphs, this results in similar legitimate, i.e. intermorph cross-pollen flow. Illegitimate pollen flow to stigmas of pin flowers, however, was much higher than to stigmas of thrum flowers. Moreover, more illegitimate pollen was transported to stigmas of pin and less to those of thrum flowers when compared with legitimate pollen flow. CONCLUSIONS: The study reveals a one-to-one reproductive inter-dependence between both partners. Data indicate that this relationship between bee species and plant species is one of the rare cases of monolecty among bees. Monotypic Ceblurgus longipalpis, the only rophitine species of Brazil, evolved prolonged mouthparts rare among short-tongued bees that enable them to access pollen from flowers with short-level anthers hidden for bees of other species, and nectar at the base of the flower tube.
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Abejas/fisiología , Cordia/fisiología , Reproducción/fisiología , Animales , Cordia/anatomía & histología , Flores/anatomía & histología , Flores/fisiología , Polinización/fisiologíaRESUMEN
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.