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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]

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]

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]

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]

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]

• 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]

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]