Nectar, floral morphology and pollination syndrome in Loasaceae subfam. Loasoideae (Cornales)

BACKGROUND AND AIMS: Loasaceae subfam. Loasoideae are mostly distributed in South America (sea level to over 4500 m) with a wide range of animals documented as pollinators. The aim was to investigate correlations between nectar parameters, flower morphology, pollination syndrome and phylogeny. METHODS: Nectar was collected from 29 species from seven genera in the subfamily. Concentration and volumes were measured and the amount of sugar calculated. Correlations of nectar data were plotted on a ternary graph and nectar characteristics compared with flower visitors, floral morphology and phylogenetic data. KEY RESULTS: Sugar concentrations are generally higher than reported for most plant families in the literature. The species investigated can be roughly grouped as follows. Group I: plants with approx. 1.5(-3.5) microL nectar with (40-)60-80% sugar and 0.19-2 mg sugar flower-1; with small, white, star-shaped corollas, pollinated by short-tongued bees. Groups II, III and IV: plants with mostly orange, balloon-, saucer-, bowl- or bell-shaped corollas. Group II: plants with approx. 9-14 microL nectar with 40-60% sugar and 4-10 mg sugar flower-1; mostly visited by long-tongued bees and/or hummingbirds. Group III: plants with 40-100 microL nectar with 30-40% sugar and 14-36 mg sugar flower-1, mostly visited by hummingbirds. Group IV: geoflorous plants with 80-90 microL with 10-15% sugar and 8.5-12 mg sugar flower-1, presumably visited by small mammals. Groups II and III include species visited by bees and/or hummingbirds. CONCLUSIONS: Pollinator switches from short-tongued bees via long-tongued bees to hummingbirds appear to have taken place repeatedly in the genera Nasa, Loasa and Caiophora. Changes in nectar amount and concentration appear to evolve rapidly with little phylogenetic constraint.     

Commensal Nematodes in the Glands,Genitalia, and Brood Cells of Bees (Apoidea)

Seven species of bees from the eastern United States, representing four families in the Apoidea, were dissected and examined for nematode associates. Dufour''s glands in females of Halictus ligatus, Augochlora pura mosieri, and Augochlorella gratiosa (Halictidae) from Florida were infested with dauer juveniles of Aduncospiculum halicti (Diplogasteridae). The Dufour''s glands of Colletes thoracicus (Colletidae) females from Maryland were infested with dauer juveniles of a new species of Koerneria sp. (Diplogasteridae), and abdominal glands of females of Andrena alleghaniensis (Andrenidae) from New York were infested with dauer juveniles of another new species of Koerneria. The lateral and median oviducts, Dufour''s glands, and poison sacs in females of Anthophora abrupta (Anthophoridae) from Maryland and Alabama were infested with dauer juveniles of a new species of Bursaphelenchus sp. (Aphelenchoididae). Cross sections of the nematode-infested poison sacs of A. abrupta revealed two types of humoral host defense reactions.     

Oil-Gathering Bees Visit Flowers of Eglandular Morphs of the Oil-Producing Malpighiaceae1

The visiting behaviour of oil-gathering, anthophorid bees on eglandular morphs of two Malpighiaceae species was observed in southeastern Brazil. The bees landed on eglandular flowers apparently by mistake, as suggested by their making one to a few scraping movements on landing, and behaving in the same way as they scrape oil glands on glandular flowers. After perceiving their mistake the bees either left the flower, making one to a few additional visits to other eglandular flowers before leaving the plant, or switched to pollen collecting. Large and medium-sized species of Centris, and some Epicharis, left the flowers after mistake visits, thus wasting time and energy, whereas small Centris and larger Epicharis switched to pollen harvesting, thus turning a mistake into a rewarding visit. Eglandular flowers of both Banisteriopsis muricata and Heteropterys aceroides attracted oil-gathering bees by deceit and probably acted as mimics of glandular flowers of their own species (automimicry). The pollination of eglandular morphs of these two Malpighiaceae species seems dependent mainly on the opportunistic, mixed oil-pollen gathering behaviour of deceived bees such as Epicharis schrottkyi. We suggest that some showy, eglandular species such as Banisteriopsis lutea may act as general mimics of other, oil-rewarding Malpighiaceae species.     

A comparative study of the ground nests of Centris flavifrons and Centris aethiocesta (Hymenoptera: Anthophoridae)

The nests of Centris aethiocesta Snelling and Centris flavifrons (Friese) are described and compared to published accounts of C. flavofasciata. The three are ground nesting solitary bee species in Costa Rica. Centris aethiocesta, like previously published C. flavofasciata, prefers the beach strand, although C. aethiocesta nests in more shaded areas. Centris flavifrons nests are constructed in the dry forest savanna, often in small depressions. All three construct one cell per tunnel, with the tunnel of completed nests filled with soil. Tunnels of completed nests of C. aethiocesta are unbranched; tunnels of C. flavifrons have 6 to 10 side tunnels also filled with soil, while only one side tunnel is published for C. flavofasciata.     

The role of nectar production, flower pigments and odour in the pollination of four species of Passiflora (Passifloraceae) in south-eastern Brazil

The pollination biology of four species of passionflower was studied in south-eastern Brazil, specifically the importance of chemical features of floral nectar, pigments and odours. All species required pollinators to produce fruits: P. alata was pollinated by bees, P. speciosa by hummingbirds, and P. galbana and P. mucronata by bats. Pollinators consumed nectar as a food source. The activity of vertebrate pollinators reflected resource availability: they foraged when large amounts of nectar were available and when quantitative resource predictability was greater. The nectar of the vertebrate-pollinated species was richer in cholesterol and phospholipids, and had a potassium-sodium ratio higher than 1.0. For all species, the light absorption of flowers was paralleled by the pollinators' visual spectral sensitivity. This first report on Passiflora floral volatile compounds showed that there was a greater chemical class diversity among the species pollinated by animals with an acute olfactory sense, such as bees and bats. Benzenoid alcohols were the most represented compounds. The fragrances contained compounds that occur in other plant species and in the exocrine secretions of bees. This study shows a strong association between pollinators and the attracting and rewarding features of flowers.     

Competition between the oligolectic beePtilothrix plumata (Anthophoridae) and the flower closing beetlePristimerus calcaratus (Curculionidae) for floral resources ofPavonia cancellata (Malvaceae)

The flowers ofPavonia cancellata, a creeping ruderal half-shrub of northeastern Brazil, open synchronously at 6:00 h with all anthers already dehisced. The oligolectic beePtilothrix plumata was the most effective pollinator. During 90—180 min, female bees make up to 40 brief pollen collection trips to provision their brood cells. The pollen of about 40 flowers ofP. cancellata is needed to feed one bee larva. The most frequent flower visitors, however, are the specialized curculionid beetlesPristimerus calcaratus, which do not crosspollinate the flowers. They perforate the epidermis with their mouthparts, provoking dehydration, and then actively close the loose petals with their legs. Two hours after opening, half of the flowers had already been closed by the beetles. We interpret the fast, uninterrupted pollen foraging ofPtilothrix plumata bees as a strategy adapted to synchronous pollen presentation ofPavonia and to competition withPristimerus calcaratus: the female bees have to provision their brood cells before the beetles succeed in closing the flowers.     

Pollination ecology of Petrocoptis grandiflora Rothm. (Caryophyllaceae); a species endemic to the north-west part of the Iberian Peninsula

Petrocoptis grandiflora Rothm. is a species endemic to the Iberian Peninsula with restricted distribution. We studied various aspects of its pollination ecology, nectar characteristics and standing crop, pollinators and nectar-robbers, and the effects of nectar robbing and supplementary pollination on fruit set. The nectar is moderately rich in saccharose (saccharose/hexose ratio 0.54), and is largely consumed by long-tongued bees (Anthophoridae). The incidence of nectar robbing by Xylocopa violncea differed between the four plant populations studied, and it had significant effects on fruit set when the population was simultaneously considered. Supplementary pollination did not improve fruit set significantly.     

Thermoregulation in four species of tropical solitary bees: the roles of size,sex and altitude

Body temperatures during free flight in the field, warm-up rates during pre-flight warm-up, and temperatures during tethered flight are measured for four tropical solitary bee species at three sites of differing altitude in Papua New Guinea. All four species are capable of endothermic preflight warm-up; three species give slopes of thoracic temperature on ambient temperature of significantly less than 1, indicating regulation of thoracic temperature. In the kleptoparasitic Coelioxys spp. (Megachilidae) and Thyreus quadrimaculatus (Anthophoridae), warm-up rates and thoracic temperatures in flight are low by comparison with the two provisioning species Creightonella frontalis (Megachilidae) and Amegilla sapiens (Anthophoridae). In both C. frontalis and A. sapiens thoracic temperatures correlate positively and significantly with both ambient temperature and body mass. In A. sapiens, body mass increases with altitude; this can be interpreted as a response to lower ambient temperatures at higher altitude, an example of Bergmann's rule. In both A. sapiens and C. frontalis populations at higher altitude have higher thoracic temperatures independent of differences of body mass, suggestive of additional morphological or physiological adaptation to lower ambient temperatures. In A. sapiens there is no qualitative difference in body temperatures between males and females after controlling for body mass, while male C. frontalis have significantly lower thoracic temperatures than females of the species. This difference between A. sapiens and C. frontalis is discussed with reference to variation in mating systems found in the Apoidea.Abbreviations C.R.I. Christensen Research Institute - P.N.G. Papua New Guinea - SFT stable flight temperature - T _a ambient air temperature - T _ab abdominal temperature - T _dif the temperature difference between thorax and abdomen - T _ex thoracic temperature excess - VFT voluntary flight temperature     

New records for the bee fauna of Iran (Hymenoptera: Apoidea)

In a survery of the bee fauna of Horand forests in East Azerbaijan province of Iran during 2008 and 2009, 46 species belonging to the families Anthophoridae, Halictidae and Megachilidae were identified. Eight species are new to the fauna of Iran: Evylaeus albipes (Fabricius, 1781), E. corvinus (Morawitz, 1878), E. israelensis (Ebmer, 1974), Seladonia desertorum (Morawitz, 1876), Heriades crenulatus Nylander, 1856, Hoplitis anthocopoides (Schenck, 1853), H. manicata (Morice, 1901) and H. rufohirta (Latreille, 1811).