Honeydew feeding in the solitary bee Osmia bicornis as affected by aphid species and nectar availability

Like honey bees (Apis mellifera), non-Apis bees could exploit honeydew as a carbohydrate source. In addition to providing carbohydrates, this may expose them to potentially harmful plant products secreted in honeydew. However, knowledge on honeydew feeding by solitary bees is very scarce. Here we determine whether the polylectic solitary bee Osmia bicornis (=O. rufa) collects honeydew under semi-field conditions, and whether this is affected by aphid species and presence of floral nectar. Bees were provided with oilseed rape plants containing flowers and/or colonies of either Myzus persicae or Brevicoryne brassicae. We used the total sugar level of the bee crop as a measure of the individual's nutritional state and the oligosaccharide erlose as indicator for honeydew consumption. Erlose was present in honeydews from both aphid species, while absent in oilseed rape nectar, nor being synthesized by O. bicornis. When bees were confined to a single honeydew type as the only carbohydrate source, consumption of M. persicae honeydew was confirmed for 47% of the bees and consumption of B. brassicae honeydew for only 3%. Increased mortality in the latter treatment provided further evidence that B. brassicae honeydew is an unsuitable food source for O. bicornis. All bees that were given the choice between honeydew and floral nectar showed significantly increased total sugar levels. However, the fact that no erlose was detected in these bees indicates that honeydew was not consumed when suitable floral nectar was available. This study demonstrates that honeydew exploitation by O. bicornis is dependent on honeydew type and the presence of floral nectar.     

Nectar by day and night:Siphocampylus sulfureus (Lobeliaceae) pollinated by hummingbirds and bats

Most species of the neotropical genusSiphocampylus are believed to be bird-pollinated. The pollination biology ofSiphocampylus sulfureus was studied in a montane region in SE Brazil. This species has features intermediate between ornithophilous and chiropterophilous syndromes: it presents a striking combination of yellowish flowers with strong odour (chiropterophilous features), and diurnal anthesis and sucrose-dominated nectar (ornithophilous features). Major pollinators were hummingbirds by day, and a phyllostomid bat by night.Siphocampylus sulfureus may be viewed as a recent derivate from the presumed ornithophilous stock within sect.Macrosiphon, and thus benefits from the activity of both diurnal and nocturnal vertebrate pollinators.Dedicated to DrIlse Silberbauer-Gottsberger and Prof. DrGerhard Gottsberger for their pioneer contribution to floral biology in Brazil.     

Adult feeding by holometabolous insects: pollen and nectar as complementary nutrient sources for Rhingia campestris (Diptera: Syrphidae)

Summary Examination of the gut contents of adult Rhingia campestris reveals that there are considerable differences in the relative amounts of pollen and nectar ingested by individual insects. Pollen, a rich protein source, is required most by females, particularly during those stages of ovarial development when yolk deposition occurs. Nectar, which is mainly carbohydrate, is required in large amounts by males, and is also required by females before and after oogenesis. These results are discussed in relation to the likely nutritional needs of the flies, and it is suggested that similar feeding patterns may be found in a variety of other flower visiting insects. Finally, reference is made to the problems of making ecological assumptions about feeding behaviour on the basis of the morphological attributes of the mouthparts.     

Nectary structure and nectar presentation in Aloe castanea and A. greatheadii var. davyana (Asphodelaceae)

This paper deals with the nectary structure and nectar presentation of two species belonging to different sections of the genus Aloe: A. castanea (Anguialoe) and A. greatheadii var. davyana (Pictae). The development of the nectary was studied by means of bright field and fluorescence light microscopy and scanning electron microscopy (SEM) in three flower stages (young, intermediate, old). Both species have septal nectaries. In A. castanea, a subsidiary tissue, not present in A. greatheadii var. davyana, was found beneath the nectary epithelium. This tissue accumulated starch that was hydrolyzed during secretion. Starch was slightly accumulated around the nectary in A. greatheadii var. davyana. The distribution of chlorophyll in the ovary was also different in the two species. These anatomical differences are not, however, correlated with greater nectar production in A. castanea. In this species, the nectary seems to degenerate after secretion, while in A. greatheadii var. davyana no sign of degeneration was observed. Differences in nectar presentation among the two species may account for different pollinators visiting their flowers.     

Absence of nitrogen fixation (acetylene reduction) by procaryotes in nectar of Banksias

Summary An earlier hypothesis that blue-green algae in the nectar ofBanksia telmatiaea contribute to the nitrogen economy of the host by fixing N₂ was tested. Field and laboratory experiments failed to demonstrate C₂H₄ production in C₂H₂-treated containers over extended periods. Soil N was not higher at the end of the flowering season and plants in which flower heads were removed prior to nectar production did not contain less N than the controls.     

Failure of the Amblyomma cajennense nymph to become infected by Theileria equi after feeding on acute or chronically infected horses

Tick-borne diseases in horses are caused by the intraerythrocytic protozoan parasites Theileria equi and Babesia caballi. Although T. equi is highly endemic in Latin America, the New World vector of this important parasite is controversial. The aim of this study was to test the ability of nymph Amblyomma cajennense ticks acquire infection by T. equi following feeding on infected horses. Three experiments were performed: tick acquisition of T. equi from an experimentally infected horse, tick acquisition of T. equi from naturally infected foals and tick acquisition of T. equi from a chronically infected horse. A. cajennense adults were dissected and salivary glands were collected in aliquots. Methyl green pyronin staining of the salivary glands did not show the presence of hypertrophy of acini or cell nuclei normally suggestive of Theileria spp. infection. The pools of salivary glands were negative for Theileria DNA in nested PCR assays. Histopathological analysis failed to detect sporoblast and sporozoites of T. equi in salivary gland acini. This study was not able to observe infection of the A. cajennense by T. equi.     

Re-thinking the classification of corticioid fungi

Corticioid fungi are basidiomycetes with effused basidiomata, a smooth, merulioid or hydnoid hymenophore, and holobasidia. These fungi used to be classified as a single family, Corticiaceae, but molecular phylogenetic analyses have shown that corticioid fungi are distributed among all major clades within Agaricomycetes. There is a relative consensus concerning the higher order classification of basidiomycetes down to order. This paper presents a phylogenetic classification for corticioid fungi at the family level. Fifty putative families were identified from published phylogenies and preliminary analyses of unpublished sequence data. A dataset with 178 terminal taxa was compiled and subjected to phylogenetic analyses using MP and Bayesian inference. From the analyses, 41 strongly supported and three unsupported clades were identified. These clades are treated as families in a Linnean hierarchical classification and each family is briefly described. Three additional families not covered by the phylogenetic analyses are also included in the classification. All accepted corticioid genera are either referred to one of the families or listed as incertae sedis.     

Phylogeny and classification of the Grimmiaceae/Ptychomitriaceae complex (Bryophyta) inferred from cpDNA

Phylogenetic relationships within the Grimmiaceae/Ptychomitriaceae were studied using a plastid tRNA cluster, including four tRNAs (trnS, trnT, trnL, trnF), a fast evolving gene (rps4), four spacers separating the coding regions, as well as one group I intron. Secondary structure analyses of the spacers as well as the trnL intron P8 domain identified several homoplastic inversions. Tracing the structural evolution of P8 we were able to identify lineage specific modifications that are mainly explained by inversions often in combination with large indel events. Phylogenetic analyses using maximum parsimony, maximum likelihood, and Bayesian methods indicate that Jaffueliobryum and Indusiella are closely related to Ptychomitrium and form the Ptychomitriaceae s. str. As Campylostelium is neither resolved within Ptychomitriaceae s. str. nor Grimmiaceae s. str., we prefer to treat it in its own family, Campylosteliaceae De Not. The systematic position of Glyphomitrium, as also found by other authors, should be considered in a broader analysis of haplolepidous mosses as our analyses indicate that it is not part of Campylosteliaceae, Grimmiaceae, or Ptychomitriaceae. Within Grimmiaceae s. str., Racomitrium is recognized as a monophyletic group sister to a clade including Dryptodon, Grimmia, and Schistidium. Coscinodon species appear disperse in Grimmia s. str. next to species sharing the same gametophyte morphology, and thus the genus is synonymized with Grimmia. Finally, Schistidium is resolved monophyletic with high statistical support, and seems to represent a rapidly evolving group of species. Our results are not fully congruent with recently published treatments splitting Grimmiaceae in a fairly high number of genera, neither with a comprehensive Grimmia including Dryptodon and Grimmia s. str.     

Relationships of herbivore feeding and plant flavonoids (Coleoptera: Chrysomelidae and Anacardiaceae: Rhus)

Summary Eighteen leaf flavonoid compounds were isolated from several populations of Rhus tripartita from xeric habitats in Israel, ornamental Schinus terebinthifolius from Israel, and three species of Rhus (vulgaris, natalensis, tenuinervis) from mesic habitats in Kenya. Foodplant preference testing of Rhus-feeding Leaf Beetles (Blepharida sacra from Israel and B. marginalis and B. conradsi from Kenya) correlated well with the flavonoid composition of the different foodplants. Blepharida sacra and B. marginalis foodplant preferences demonstrated an herbivore sibling relationship but there is evidence, including foodplant ecology and distribution, that they are separate species. The herbivorefoodplant coevolution of the xeric B. sacra-R. tripartita is distinct from that of the mesic B. marginalis-R. vulgaris/natalensis, however, this study also indicates possible ancestral relationships between the herbivore species as well as between the plant species.     

Induced resistance in intertidal macroalgae modifies feeding behaviour of herbivorous snails

Herbivory in terrestrial and marine systems can induce changes in plant chemistry affecting the foraging behaviour of herbivores. A model based on terrestrial plant-herbivore interactions predicts herbivory-induced changes in leaf chemistry to be manifested in (1) increased herbivore mobility, (2) increased feeding dispersal and (3) reduced tissue consumption by herbivores. This study is the first to demonstrate that herbivory-induced changes in the tissue chemistry of the brown seaweed Ascophyllum nodosum elicit the same response in the feeding behaviour of the gastropod Littorina obtusata as predicted for herbivorous insects, providing good evidence for the models validity across different ecosystems. The potential benefit of increased feeding dispersal to terrestrial plants as suggested by the model is the prevention of concentrated damage to apical tissues thereby preserving the plants ability to compete for light; A. nodosum does not conform to these predictions. Increased dispersal of feeding damage on A. nodosum away from primary frond tissues would reduce the likelihood of frond breakage implying a fitness benefit of induced resistance.     

A laboratory study of the feeding of Mesostoma lingua (Schmidt) (Turbellaria: Neorhabdocoela) on Daphnia magna Straus at four different temperatures

Mesostoma lingua eats 0.8 Daphnia magna at 15 °C, and 2.04 at 30 °C. Below 0.5 Daphnia per day (D d^–1) hunger occurs, at any temperature, and mortality increases sharply. The functional response curve appears to be linear, but saturation was not fully reached at 5 D d^–1, the highest food level applied in the present study. All food regimes (above hunger level) and temperature regimes differed significantly from each other; factor interactions were of increasing importance at higher temperatures.Longevity, above hunger level, decreased with temperature. Peak longevity at low temperature may be weakly associated with relatively low food levels.     

Evidence of interference of Asterionella formosa with the feeding of Bosmina longirostris: a field study in a south Andes lake

Intensive sampling of a small temperate lake of the Araucanian region (Argentina), revealed changes in the demography of Bosmina longirostris when the diatom Asterionella formosa density increased (to 54 000 cells ml^–1). Bosmina population behaviour in the field was consistent with the idea that large numbers of Asterionella caused its starvation. Individuals were actually colourless and fecundity dropped to zero, as was evident when Asterionella reached 99.4% of total phytoplankton biovolume. Since cyanophytes, as a whole, are scarce in these lakes, we propose that the flagellate/diatom ratio has a direct effect on cladoceran demography.     

Efficiency of facultative frugivory in the nectar-feeding bat Glossophaga commissarisi: the quality of fruits as an alternative food source

The efficiency of food exploitation correlates positively with the extent of dietary specialization. Neotropical nectar-feeding bats (Glossophaginae) have one of the most specialized diets among mammals, as floral nectar constitutes a sugar-rich and highly digestible but protein and fiber depleted food source. However, dietary constraints, such as a temporary scarcity of nectar, or protein demands may sometimes require the uptake of alternative food items. We investigated the influence of a diet switch from nectar to fruit on intestinal morphology, body mass, and energy budget in the nectar-feeding bat Glossophaga commissarisi and quantified feeding efficiency. We hypothesized that these nectar specialists depend on a constant supply of nectar, if they were lacking the ability for morphological and physiological plasticity in response to a fiber-rich diet. Although capable of harvesting infructescences of Piper hispidum, G. commissarisi was less efficient in extracting energy from fruits (48% digestive efficiency of total fruit energy content) than from nectar (c. 99% digestive efficiency). The intestinal morphology and organ masses did not change after bats were switched from nectar to fruits. Captive bats exhibited lower daily energy expenditures and flight activity when feeding on fruits than during nectarivory. Possibly, this may have been a deliberate regulation to balance reduced feeding efficiency, or simply the consequence of extended digestive pauses. The low digestibility of Piper, in combination with slow digestion and the bats’ inability for morphological and physiological plasticity may cause nectar-feeders to reduce their maximum energy expenditure when feeding on fruits. We argue that although fruits may substitute for nectar, they may cause restricted maximum energy assimilation compared with nectar.