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Simple Summary: Female frog-biting midges exclusively feed on blood from frogs. They are attracted by the calling of male frogs and search for specific feeding sites on their host's body. To feed, these blood-feeding midges use a very short proboscis that is composed of six piercing structures and an enclosing component. We analyzed the morphology of the mouthparts using SEM and compared these with the well-studied proboscises of other blood-feeding flies. Females of Corethrella share more similarities to the very small blood-feeding short-proboscid biting midges, black flies and sand flies than to their more closely related long-proboscid mosquitoes. We interpret our findings in the functional context of a very short piercing proboscis and its possible specialization to pierce frogs. Females of frog-biting midges (Corethrellidae) obtain their blood meals from male calling frogs. While the morphology of the feeding apparatus is well studied in hematophagous Diptera that impact humans, frog-biting midges have received far less attention. We provide a detailed micromorphological examination of the piercing blood-sucking proboscis and maxillary palpus in three Corethrella species using scanning electron microscopy and histological semi-thin sectioning. We also compare the sensilla found on the proboscis tip and the palpus of Corethrella with other piercing blood-sucking Diptera. Corethrella spp. have a proboscis length of about 135 µm, equipped with delicate mandibular piercing structures composing the food canal together with the labrum and hypopharynx. Their proboscis composition is plesiomorphic and more similar to other short-proboscid hematophagous Culicomorpha (e.g., Simuliidae), in contrast to the phylogenetically more closely related long-proboscid Culicidae. As in other short-proboscid taxa, the salivary canal in Corethrella spp. transitions into an open salivary groove with one mandible forming a seal, whereas in Culicidae the salivary canal is closed until the tip of the proboscis. We discuss the possible functional constraints of very short, piercing blood-sucking proboscises (e.g., dimensions of host blood cells) that may limit the size of the food canal. [ABSTRACT FROM AUTHOR]

An appreciation of body size allometry is central for understanding insect pollination ecology. A recent model utilises allometric coefficients for five of the seven extant bee families (Apoidea: Anthophila) to include crucial but difficult-to-measure traits, such as proboscis length, in ecological and evolutionary studies. Melittidae were not included although they are important pollinators in South Africa where they comprise an especially rich and morphologically diverse fauna. We measured intertegular distance (correlated with body size) and proboscis length of 179 specimens of 11 species from three genera of Melittidae. With the inclusion of Melittidae, we tested the between family differences in the allometric scaling coefficients. AIC model selection was used to establish which factors provide the best estimate of proboscis length. We explored a hypothesis that has been proposed in the literature, but which has not been tested, whereby body and range sizes of bees are correlated with rainfall regions. We tested this by using body size measurements of 2109 museum specimens from 56 species of Melittidae and applied the model coefficients to estimate proboscis length and foraging distance. Our results from testing differences across bee families show that with the addition of Melittidae, we retained the overall pattern of significant differences in the scaling coefficient among Apoidea, with our model explaining 98% of the variance in species-level means for proboscis length. When testing the relationship between body size and rainfall region we found no relationship for South African Melittidae. Overall, this study has added allometric scaling coefficients for an important bee family and shown the applicability of using these coefficients when linked with museum specimens to test ecological hypothesis. [ABSTRACT FROM AUTHOR]

Glomeremus orchidophilus (Gryllacrididae) is a flower visiting cricket on the tropical island La Réunion. This species is the only Orthoptera shown to be a pollinator of a plant. We studied its nectar feeding behavior and mouthpart morphology in detail. Since G. orchidophilus possesses biting-and-chewing mouthparts, our objective was to find behavioral and/or structural specializations for nectar-feeding. The comparative analysis of feeding behavior revealed that fluid is taken up without movements of the mouthparts in Glomeremus . A comparative morphological examination of two Glomeremus species, together with several representatives of other Gryllacrididae and other Ensifera taxa revealed subtle adaptations to fluid feeding in Glomeremus . All representatives of Gryllacrididae were found to possess a distinct patch of microtrichia at the tip of their galeae. However, in Glomeremus a channel is formed between the distal components of the maxillae and the mandibles on each side of the body. Micro-CT and SEM examination revealed a longitudinal groove that extends over the galea beginning at the patch of microtrichia in the studied Glomeremus species. We hypothesize that the microtrichia take up fluid by capillarity and the action of the cibarium and pharyngeal pumps transports fluid along the channels between the maxillae and mandibles into the preoral cavity. These mouthpart features allow nectar uptake from flowers that is unique in Orthoptera. [ABSTRACT FROM AUTHOR]

Urbanization is a global phenomenon that is encroaching on natural habitats and decreasing biodiversity, although it is creating new habitats for some species. The Eurasian kestrel (Falco tinnunculus) is frequently associated with urbanized landscapes, but it is unclear what lies behind the high densities of kestrels in the urban environment. Occupied nest sites in the city of Vienna, Austria, were investigated along a gradient of urbanization (percentage of land covered by buildings or used by traffic). Field surveys determined the abundance of potential prey (birds and rodents), and the results were compared to the birds' diets. A number of breeding parameters were recorded over the course of three years. High breeding densities in urban habitats do not necessarily correlate with high habitat quality. The high density of kestrel nests in the city center is probably due to the ready availability of breeding cavities. Highly urbanized areas in Vienna are associated with unexpected costs for the city-dwelling raptor, in terms both of prey availability and of reproductive success. The kestrel appears to be exploiting the urban environment but, given the poor reproductive performance of urban kestrels, it is likely that the species is falling into an ecological trap. [ABSTRACT FROM AUTHOR]

A well-developed suction pump in the head represents an important adaptation for nectar-feeding insects, such as Hymenoptera, Lepidoptera and Diptera. This pumping organ creates a pressure gradient along the proboscis, which is responsible for nectar uptake. The extremely elongated proboscis of the genus Prosoeca (Nemestrinidae) evolved as an adaptation to feeding from long, tubular flowers. According to the functional constraint hypothesis, nectar uptake through a disproportionately elongated, straw-like proboscis increases flower handling time and consequently lowers the energy intake rate. Due to the conspicuous length variation of the proboscis of Prosoeca, individuals with longer proboscides are hypothesised to have longer handling times. To test this hypothesis, we used field video analyses of flower-visiting behaviour, detailed examinations of the suction pump morphology and correlations of proboscis length with body length and suction pump dimensions. Using a biomechanical framework described for nectar-feeding Lepidoptera in relation to proboscis length and suction pump musculature, we describe and contrast the system in long-proboscid flies. Flies with longer proboscides spent significantly more time drinking from flowers. In addition, proboscis length and body length showed a positive allometric relationship. Furthermore, adaptations of the suction pump included an allometric relationship between proboscis length and suction pump muscle volume and a combination of two pumping organs. Overall, the study gives detailed insight into the adaptations required for long-proboscid nectar feeding, and comparisons with other nectar-sucking insects allow further considerations of the evolution of the suction pump in insects with sucking mouthparts. [ABSTRACT FROM AUTHOR]

Simple Summary: Adult Yellowjackets only take up sugar-rich liquid for their daily diet. As these fluids are usually collected from sources with high amounts of various particles, such as fruit flesh or shards of bark, it is important to filter these particles, especially as these animals have a wasp waist with a constriction of the gut, through which the ingested fluid has to pass. We conducted experiments with variously-sized glass particles that were provided in a sugar solution. Female workers of the German Wasp were X-rayed after the food uptake. Possible areas of filtration were investigated with scanning electron microscopy to visualize the surface structures. We could identify two possible areas with filtration function. The first is at the frontal part of the mouthparts, at which the animals could prevent the uptake of particles that were larger than 0.2 mm. A second area inside the head with rows of interlinking hair-like structures enables much finer filtration. Particles that were bigger than 0.15 mm were reliably filtered. The particles that were filtered at this second filtration area were stored in a pouch-like organ inside the head. Smaller particles were also filtered, but some of these were able to pass. These results demonstrate fluid filtration, a poorly-studied topic of insect morphology and behavior. The mouthparts of Vespidae have evolved to forage various solid and liquid foods, such as animal prey, carbohydrate-rich fluids, as well as woody fibres for nest construction. Before nutritional fluids are ingested into the crop, bigger particles need to be filtered out. This study examined the functional morphology of the mouthparts, the preoral cavity, and the proximal alimentary tract inside the head focusing on this filtration process. The feeding organs and preoral cavity were studied using µCT and SEM that were complimented by feeding experiments with glass beads in workers of Vespula germanica. To visualize fluid ingestion into the head and alimentary tract, barium sulfate solution was used as contrast agent; a method that is rarely applied in entomology. Experimental results indicate that large glass beads (>212 µm) were filtered by the mouthpart structures before entering the preoral cavity. Smaller glass beads (152–212 µm) were found inside the infrabuccal pocket in front of the mouth. Morphological evidence indicates that cuticle structures of the epipharynx, hypopharynx, and cibarium filter this particle size inside the preoral cavity while glass beads < 152 µm reach the crop. A double fluid filtration system is proposed that is formed by (1) bristles of the mouthparts and (2) microtrichia of the preoral cavity. [ABSTRACT FROM AUTHOR]

The insects with the longest proboscis in relation to body length are the nectar-feeding Nemestrinidae. These flies represent important pollinators of the South African flora and feature adaptations to particularly long-tubed flowers. The present study examined the morphology of the extremely long and slender mouthparts of Nemestrinidae for the first time. The heavily sclerotized tubular proboscis of flies from the genus Prosoeca is highly variable in length. It measures 20-47 mm in length and may exceed double the body length in some individuals. Proximally, the proboscis consists of the labrum-epipharynx unit, the laciniae, the hypopharynx, and the labium. The distal half is composed of the prementum of the labium, which solely forms the food tube. In adaptation to long-tubed and narrow flowers, the prementum is extremely elongated, bearing the short apical labella that appear only to be able to spread apart slightly during nectar uptake. Moving the proboscis from resting position under the body to a vertical feeding position is accomplished in particular by the movements of the laciniae, which function as a lever arm. Comparisons with the mouthparts of other flower visiting flies provide insights into adaptations to nectar-feeding from long-tubed flowers. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ••, ••-••. [ABSTRACT FROM AUTHOR]

Abstract: This review compares the mouthparts and their modes of operation in blood-feeding Arthropoda which have medical relevance to humans. All possess piercing blood-sucking proboscides which exhibit thin stylet-shaped structures to puncture the host''s skin. The tips of the piercing structures are serrated to provide anchorage. Usually, the piercing organs are enveloped by a soft sheath-like part which is not inserted. The piercing process includes either back and forth movements of the piercing structures, or sideways cutting motions, or the apex of the proboscis bears teeth-like structures which execute drilling movements. Most piercing-proboscides have a food-canal which is separate from a salivary canal. The food-canal is functionally connected to a suction pump in the head that transports blood into the alimentary tract. The salivary canal conducts saliva to the tip of the proboscis, from where it is discharged into the host. Piercing blood-sucking proboscides evolved either from (1) generalized biting-chewing mouthparts, (2) from piercing mouthparts of predators, or plant sap or seed feeders, (3) from lapping or sponging mouthparts. Representatives of one taxon of Acari liquefy skin tissue by enzymatic action. During feeding, many blood-feeding arthropods inadvertently transmit pathogens, which mostly are transported through the discharged saliva into the host. [Copyright &y& Elsevier]

The article focuses on a research conducted in order to describe pollen processing behavior of Heliconius butterflies. It discusses the pollen processing behavior as a derived proboscis grooming behavior which allowsHeliconius butterflies to utilize the pollen adhering to the proboscis as a source of nutrient. The study revealed the pollen processing behavior of Heliconius as a modified proboscis grooming behavior.

The form and function of the mouthparts in adult Lepidoptera and their feeding behavior are reviewed from evolutionary and ecological points of view. The formation of the suctorial proboscis encompasses a fluid-tight food tube, special linking structures, modified sensory equipment, and novel intrinsic musculature. The evolution of these functionally important traits can be reconstructed within the Lepidoptera. The proboscis movements are explained by a hydraulic mechanism for uncoiling, whereas recoiling is governed by the intrinsic proboscis musculature and the cuticular elasticity. Fluid uptake is accomplished by the action of the cranial sucking pump, which enables uptake of a wide range of fluid quantities from different food sources. Nectar-feeding species exhibit stereotypical proboscis movements during flower handling. Behavioral modifications and derived proboscis morphology are often associated with specialized feeding preferences or an obligatory switch to alternative food sources. [ABSTRACT FROM AUTHOR]

The Neotropical Heliconius butterflies are well known to supplement their nectar diet by active pollen collecting. They extract proteins and free amino acids from pollen grains, exhibiting a particular behavior that involves the use of a fluid of uncertain origin. It has been assumed that this fluid is either regurgitated nectar or saliva, because for anatomical reasons a butterfly is able to release only these two fluids through its proboscis. In an experimental approach, 27 individuals of Heliconius melpomene (L.) were given red-dyed sugar solution and subsequently we observed whether the fluid used in pollen feeding was dyed or not dyed. Because regurgitated nectar should contain sugar, fluid samples were taken from the proboscis of butterflies from natural populations in Costa Rica. Samples of 44 individuals from seven species were tested for the presence of fructose and glucose with the aid of aniline phthalate. This study is the first detailed investigation of the origin of the fluid used by Heliconius butterflies in pollen feeding. The results are discussed in terms of already existing hints in literature concerning the true nature of that fluid. [ABSTRACT FROM AUTHOR]

The Neotropical genus Heliconius (Nymphalidae) is unique among butterflies for its pollen-feeding behaviour. With the application of saliva, they extract amino acids from pollen grains on the outside of the proboscis. We predicted that the salivary glands of pollen-feeding Heliconiinae would show adaptations to this derived feeding behaviour. A biometrical analysis of the salivary glands revealed that pollen-feeding butterflies of the genus Heliconius have disproportionately longer and more voluminous salivary glands than nonpollen-feeding Nymphalidae. The first two components in the principal component analysis explained approximately 95% of the total variance. The size-dependent factor score coefficients of body length and salivary gland parameters were predominately represented on axis 1. They significantly discriminated pollen-feeding from nonpollen-feeding heliconiines on that axis. Factor score coefficients for the volume of the secretory region of the salivary glands separated heliconiines from the outgroup species. The detailed biometrical analysis of salivary glands features thus provides strong evidence that the secretory regions of the salivary glands are larger in pollen-feeding butterflies. We concluded that pollen feeding is associated with a high production of salivary fluid. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 604–612. [ABSTRACT FROM AUTHOR]

The mouthparts of the spoon-winged lacewing Nemoptera sinuata are adapted for the uptake of pollen and nectar. Form and function of the mouthparts are described, and the technique of food uptake is discussed in context with flower-visiting behaviour and floral architecture of the preferred flowers. The maxillae are the main organs for food uptake. The brush-shaped laciniae, galeae and maxillary palpi form a functional unit which can be extended by the action of the cardo-stipes joint. Video analyses of the mouthpart movements distinguished different patterns of maxillary motions which occur in nectar feeding or pollen collecting. The flower-visiting behaviour and the specialised mouthparts of the Nemopteridae are derived traits which probably evolved from predatory and biting/chewing mouthparts within the Neuroptera. [ABSTRACT FROM AUTHOR]

Adult butterflies feed from a variety of substrates and have appropriate adaptations. We examined proboscis morphology in a community of fruit-feeding butterflies (Nymphalidae) in a tropical forest in Uganda. These data were supplemented with behavioural observations and measurements of intake rate on natural and artificial substrates. We found no sexual dimorphism in proboscis morphology even though puddling behaviour is usually performed by males. Two main feeding techniques could be distinguished on the basis of behaviour and morphology: the piercing technique, typically found in Charaxinae, and the sweeping technique employed by both Nymphalinae and Satyrinae. These techniques, distinguished in previous studies, are described in more detail and their relative efficiencies are discussed in the context of sexual dimorphism, food-choice and life history evolution. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 86, 333–343. [ABSTRACT FROM AUTHOR]

Abstract: The food canal of the proboscis of Lepidoptera serves for the uptake of nutrient fluids and the discharge of saliva. A valve was discovered at the entrance to the sucking pump in the head that separates these countercurrent flows in nymphalid butterflies. Three species of Nymphalidae were examined by dissections and light microscopic serial semithin sections. The sucking pump is a unit composed of three structures: (1) the oral valve, which is a projection of the epipharynx extending into the anterior cibarial lumen, (2) the expandable lumen, and (3) the posterior sphincter valve which controls influx into the oesophagus. Based on the microanatomical results, a functional model is presented to account for the uptake and swallowing of fluids and for the control of the salivary flow into the food canal of the proboscis. Dilator muscles of the sucking pump expand the lumen by pulling on the muscular dorso-anterior side. This opens the oral valve and fluid can be drawn into the lumen from the food canal of the proboscis. Circular compressor muscles which attach to both sides of the sclerotized ventro-posterior wall of the sucking pump reduce the size of the lumen; passively they close the oral valve and press fluid through the relaxed posterior sphincter opening into the oesophagus. According to this model saliva can be discharged into the food canal during the swallowing phase. The oral valve and pumping unit are similar in all studied species despite the fact that saliva presumably plays a special role in the derived pollen-feeding behaviour of one of them, viz. Heliconius melpomene. [Copyright &y& Elsevier]

Abstract: This review deals with the morphology and function of adult insect mouthparts modified to feed on nectar, pollen or petals. Specialization to nectar-feeding is evident in formation of proboscides of various lengths and designs. Proboscides of many Hymenoptera and Diptera function according to adhesion mechanisms that load nectar onto extensible apical mouthpart regions before fluid is conveyed along the food canal to the mouth by capillarity and suction. Predominantly suctorial proboscides evolved once in Lepidoptera, probably twice in Coleoptera, variously in some Hymenoptera and several times with similar design in Diptera. Many of them are particularly long and have sealed food tubes, specialized apical regions, new proboscis resting positions and modified feeding movements. Mouthparts of obligate pollen-feeding insects can be characterized by modified mandibles, specialized bristles for pollen manipulation and elaborate feeding movements. Often saliva is crucial for pollen retention and ingestion. In Coleoptera, intact pollen is gathered by sweeping movements of mouthparts; in Diptera, it is suspended in saliva prior to suction. Pollen is crushed by asymmetrical mandibles in aglossatan Lepidoptera and one group of basal Hymenoptera. Pollen-piercing mouthparts occur in Thysanoptera and one group of Diptera. Some butterflies and few Diptera extract nutrients from pollen by mixing it externally with saliva on their mouthparts. No mouthpart specializations to petal-feeding are reported in flower-visiting insects. [Copyright &y& Elsevier]

The morphology and functional anatomy of the mouthparts of pollen wasps (Masarinae, Hymenoptera) are examined by dissection, light microscopy and scanning electron microscopy, supplemented by field observations of flower visiting behavior. This paper focuses on the evolution of the long suctorial proboscis in pollen wasps, which is formed by the glossa, in context with nectar feeding from narrow and deep corolla of flowers. Morphological innovations are described for flower visiting insects, in particular for Masarinae, that are crucial for the production of a long proboscis such as the formation of a closed, air-tight food tube, specializations in the apical intake region, modification of the basal articulation of the glossa, and novel means of retraction, extension and storage of the elongated parts. A cladistic analysis provides a framework to reconstruct the general pathways of proboscis evolution in pollen wasps. The elongation of the proboscis in context with nectar and pollen feeding is discussed for aculeate Hymenoptera. [Copyright &y& Elsevier]

Abstract: The anatomy of the proboscis was studied in representatives of all major subfamilies of Papilionoidea and several outgroup taxa which included Hesperiidae, Hedylidae and Geometroidea. In all species the cross-sectional outline of the tapering proboscis continuously changes from proximal to the tip while the central food canal, formed by the concave medial galeal walls, retains its oval shape. Each galea contains three types of muscles, a branching trachea, nerves, sensilla, and at least one longitudinal septum. We focused on the varying arrangement and distribution of the intrinsic galeal muscles from the basal galeal joint to the tip region. The plesiomorphic condition of the galeal composition of Papilionoidea is regarded to include one basal intrinsic muscle in the basal joint region and two series of intrinsic muscles, i.e. the lateral intrinsic galeal muscles and the median intrinsic galeal muscles, both series extending from the proximal region to the tip region. The plesiomorphic arrangements of the intrinsic muscle series are found in all representatives of Papilionidae, in one species of Lycaenidae (sensu lato), in many Nymphalidae (sensu lato), and in all outgroup species. Three apomorphic character states are distinguished regarding the presence and extension of the median intrinsic galeal muscles. (1) Present up to 35% of the proboscis length and absent distally in Pieridae, Lycaeninae (Lycaenidae), Satyrinae (Nymphalidae), and Danainae (Nymphalidae). (2) Present in the proximal third of the proboscis and again near the tip between 80 and 90% of the proboscis length in the examined Heliconiinae (Nymphalidae). (3) Completely absent, as in one lycaenid species from the subfamily Riodininae. [Copyright &y& Elsevier]

Abstract Krenn, H. W. 2000. Proboscis musculature in the butterfly Vanessa cardui (Nymphalidae, Lepidoptera): settling the proboscis recoiling controversy. —Acta Zoologica (Stockholm) 81: 259–266 The proboscis of Vanessa cardui (Nymphalidae) contains two basal galeal muscles and two different series of numerous oblique muscles. Both muscle series extend from the proximal region up to the tip-region; the individual muscles of each series run a constant course throughout the proboscis. In contrast to other butterflies, the knee bend region does not have additional types of muscles. The analysis of shock-frozen proboscises reveals that the dorsal wall is arched outwardly in the uncoiled, feeding position whereas in the coiled, resting position the dorsal proboscis wall is flat or concave. This results in a significantly greater cross-sectional area due to the significantly greater dorso-ventral diameter in uncoiled proboscises. After freezing the proboscis in its distal region, it can still be uncoiled, however, it cannot be fully recoiled. These morphometric and experimental results indicate that the oblique proboscis muscles are responsible for recoiling the proboscis to the resting position. [ABSTRACT FROM AUTHOR]

Simple Summary: Flies with a particularly long proboscis are characteristic of flower-visiting insects in the Greater Cape Floristic Region of South Africa. We studied an endemic nemestrinid fly species in a small isolated area of semi-natural vegetation where these insects were the only flower visitors that could drink nectar from the available long-tubed flowers of one plant species. We examined the mouthpart structures that are important for nectar uptake and the length and diameter of the proboscis in comparison with the flower sizes. This local one-to-one interaction between the fly population and its nectar host flower gave the opportunity to quantify the nectar resources available for the nemestrinid flies at the study site. By comparing the offered nectar volumes before and after flower visits, the average meal size could be estimated. Assessments of the nectar levels from measured quantities and flower size allowed us to make predictions of how various proboscis lengths could reach nectar inside floral tubes. Several Prosoeca (Nemestinidae) species use a greatly elongated proboscis to drink nectar from long-tubed flowers. We studied morphological adaptations for nectar uptake of Prosoecamarinusi that were endemic to the Northern Cape of South Africa. Our study site was a small isolated area of semi-natural habitat, where the long-tubed flowers of Babiana vanzijliae (Iridaceae) were the only nectar source of P. marinusi, and these flies were the only insects with matching proboscis. On average, the proboscis measured 32.63 ± 2.93 mm in length and less than 0.5 mm in diameter. The short labella at the tip are equipped with pseudotracheae that open at the apical margin, indicating that nectar is extracted out of the floral tube with closed labella. To quantify the available nectar resources, measurements of the nectar volume were taken before the flies were active and after observed flower visits. On average, an individual fly took up approximately 1 µL of nectar per flower visit. The measured nectar quantities and the flower geometry allowed estimations of the nectar heights and predictions of necessary proboscis lengths to access nectar in a range of flower tube lengths. [ABSTRACT FROM AUTHOR]

Abstract: Few species of true butterflies (Lepidoptera: Papilionoidea) have evolved a proboscis that greatly exceeds the length of the body. This study is the first to examine the morphology of an extremely long butterfly proboscis and to describe how it is used to obtain nectar from flowers with very deep corolla tubes. The proboscis of Eurybia lycisca (Riodinidae) is approximately twice as long as the body. It has a maximal length of 45.6 mm (mean length 36.5 mm ± 4.1 S.D., N = 20) and is extremely thin, measuring only about 0.26 mm at its maximum diameter. The proboscis has a unique arrangement of short sensilla at the tip, and its musculature arrangement is derived. The flower handling times on the preferred nectar plant, Calathea crotalifera (Marantaceae), were exceptionally long (mean 54.5 sec ± 28.5 S.D., N = 26). When feeding on the deep flowers remarkably few proboscis movements occur. The relationship between Eurybia lycisca and its preferred nectar plant and larval host plant, Calathea crotalifera, is not mutualistic since the butterfly exploits the flowers without contributing to their pollination. We hypothesize that the extraordinarily long proboscis of Eurybia lycisca is an adaptation for capitalizing on the pre-existing mutualistic interaction of the host plant with its pollinating long-tongued nectar feeding insects. [Copyright &y& Elsevier]

• The erection angles of microtrichia were added in the modified model of honey bees. • A model was proposed to evaluate the volumetric and energetic intake rate of orchid bees. • The honey bees have higher volumetric and energetic intake rate compared with orchid bees. Bees (Apidae) are flower-visiting insects that possess highly efficient mouthparts for the ingestion of nectar and other sucrose fluids. Their mouthparts are composed of mandibles and a tube-like proboscis. The proboscis forms a food canal, which encompasses a protrusible and hairy tongue to load and imbibe nectar, representing a fluid-feeding technique with a low Reynolds number. The western honey bee, Apis mellifera ligustica , can rhythmically erect the tongue microtrichia to regulate the glossal shape, achieving a tradeoff between nectar intake rate and viscous drag. Neotropical orchid bees (Euglossa imperialis) possess a proboscis longer than the body and combines this lapping-sucking mode of fluid-feeding with suction feeding. This additional technique of nectar uptake may have different biophysics. In order to reveal the effect of special structures of mouthparts in terms of feeding efficiency, we build a temporal model for orchid bees considering fluid transport in multi-states including active suction, tongue protraction and viscous dipping. Our model indicates that the dipping technique employed by honey bees can contribute to more than seven times the volumetric and energetic intake rate at a certain nectar concentration compared with the combined mode used by orchid bees. The high capability of the honey bee's proboscis to ingest nectar may inspire micropumps for transporting viscous liquid with higher efficiency. [ABSTRACT FROM AUTHOR]

Neotropical orchid bees (Euglossini) possess the longest proboscides among bees. In this study, we compared the feeding behavior and functional morphology of mouthparts in two similarly large-sized species of Euglossa that differ greatly in proboscis length. Feeding observations and experiments conducted under semi-natural conditions were combined with micro-morphological examination using LM, SEM and micro CT techniques. The morphometric comparison showed that only the components of the mouthparts that form the food tube differ in length, while the proximal components, which are responsible for proboscis movements, are similar in size. This study represents the first documentation of lapping behaviour in Euglossini. We demonstrate that Euglossa bees use a lapping-sucking mode of feeding to take up small amounts of fluid, and a purely suctorial technique for larger fluid quantities. The mouthpart movements are largely similar to that in other long-tongued bees, except that the postmentum in Euglossa can be extended, greatly enhancing the protraction of the glossa. This results in a maximal functional length that is about 50% longer than the length of the food canal composing parts of the proboscis. The nectar uptake and the sensory equipment of the proboscis are discussed in context to flower probing. [ABSTRACT FROM AUTHOR]

Female Pangoniinae in the tabanid fly genus Philoliche can display remarkably elongated proboscis lengths, which are adapted for both blood- and nectar-feeding. Apart from their role as blood-sucking pests, they represent important pollinators of the South African flora. This study examines the morphology of the feeding apparatus of two species of long-proboscid Tabanidae: Philoliche rostrata and Philoliche gulosa – both species display adaptations for feeding from a diverse guild of long-tubed flowers, and on vertebrate blood. The heavily sclerotised proboscis can be divided into two functional units. The short, proximal piercing part is composed of the labrum-epipharynx unit, the hypopharynx and paired mandible and maxilla. The foldable distal part is composed of the prementum of the labium which solely forms the food canal and is responsible for nectar uptake via the apical labella. The proboscis works as a drinking straw, relying on a pressure gradient provided by a two-part suction pump in the head. Both proboscis and body lengths and suction pump dimensions show a significantly correlated allometric relationship with each other. This study provides detailed insights into the adaptations for a dual diet using an elongated sucking proboscis, and considers these adaptations in the context of the evolution of nectar feeding in Brachycera. [ABSTRACT FROM AUTHOR]