Klaus Lunau

Heinrich-Heine-Universität Düsseldorf | HHU · Department of Biology

Flower colour is an important mediator of plant-pollinator interactions. While the reflectance of light from the flower surface and background are governed by physical properties, the perceptual interpretation of such information is generated by complex multilayered visual processing. Should quantitative modelling of flower signals strive for repea...

The flower perianth has various, non-mutually exclusive functions, such as visual signalling to pollinators and protecting the reproductive organs from the elements and from florivores, but how different perianth structures and their different sides play a role in these functions is unclear. Intriguingly, in many species there is a clear colour dif...

Floral colours represent a highly diverse communication signal mainly involved in flower visitors' attraction and guidance, but also flower discrimination, filtering non‐pollinators and discouraging floral antagonists. The divergent visual systems and colour preferences of flower visitors, as well as the necessity of cues for flower detection and d...

Pollination by small non-flying mammals occurs in Africa, Australia, Asia and the Neotropics. One hotspot is in the winter rainfall zone of the Cape Floral Region of South Africa. This phenomenon is known for a handful of plant lineages, of which one comprises geoflorous monocots including the tribe Hyacintheae of the Asparagaceae. Small mammal pol...

In pollen-limited plant communities, the foraging behavior of pollinators might mediate coexistence and competitive exclusion of plant species by determining which plants receive conspecific pollen. A key question is whether realistic pollinator foraging behavior promotes coexistence or exclusion of plant species. We use a simulation model to under...

Pollen grains of Malvoideae (Malvaceae) which corbiculate bees cannot collect constitute a floral filter that excludes pollen-collecting bumble bees and honey bees from exploiting pollen resources. Although large, spiny pollen grains are in fact harder to compact for collection by corbiculate bees, pollen morphology (e.g., grain diameter, spine len...

Within a community, co-occurring plant species are expected to diverge in floral display or flowering phenology to decrease interspecific competition and thus increase intraspecific pollination. However, co-occurring species can also benefit from floral signal standardisation (similar colour signals among flowers of different species) because it fa...

List of publications as of March 2023

Monosymmetry in flowers has evolved many times from ancestors with polysymmetrical flowers. Flower symmetry characteristics often lack intraspecific variability. The genus Saxifraga represents an exception with high variations of floral symmetry between and within species and even within individual plants. Lab-based studies could show that this var...

Flowers have many traits to appeal to pollinators, including ultraviolet (UV) absorbing markings, which are well-known for attracting bees at close proximity (e.g., <1 m). While striking UV signals have been thought to attract pollinators also from far away, if these signals impact the plant pollinia removal over distance remains unknown. Here, we...

Beside insects, sengis also consume plant material such as leaves, fruits, seeds and floral nectar. It is known that they use olfaction for foraging, but little is known about their vision and visual learning capabilities. Colour vision has been tested in two species, showing that they are likely dichromats (green- and blue-sensitive retinal cone-p...

Magnetic resonance imaging (MRI) is the key whole-body imaging technology for observing processes within a living object providing excellent resolution and contrast between soft tissues. In the present work, we exploited the non-destructive properties of MRI to track longitudinally the dynamic changes that take place in developing pupae of the Empe...

Zusammenfassung: Das Farbensehen von Bienen unterscheidet sich von dem des Menschen dadurch, dass Bienen ultraviolettes Licht sehen können, aber unempfi ndlich für rotes Licht sind. Blumenfarben, die in Anpassung an Bienen als Bestäuber entstanden sind, sind nicht für das Farben-sehen des Menschen, sondern für das der Bienen gemacht. Für Bienen ist...

Bees play a vital role as pollinators worldwide and have influenced how flower colour signals have evolved. The Western honey bee, Apis mellifera (Apini), and the Buff-tailed bumble bee, Bombus terrestris (Bombini) are well-studied model species with regard to their sensory physiology and pollination capacity, although currently far less is known a...

Bergwiesen und -weiden oberhalb der Baumgrenze sind Paradiese aus Menschenhand. Unterschiede in Höhe, Mikroklima, Boden und Bewirtschaftung schaffen eine beeindruckende Biodiversität. Der Artenreichtum sorgt für die Stabilisierung des Ökosystems Bergwiese und Bergweiden. Blütenbestäubende Insekten sind dabei eine unverzichtbare Nahtstelle zwischen...

Flowers have many sensory traits to appeal to pollinators, including ultraviolet (UV) absorbing markings, which are well known for attracting bees at close proximity (e.g. < 1 m). While striking UV signals have been thought to attract pollinators also at greater distances of meters, how the signals impact the plant pollination success over distance...

Magnetic resonance imaging (MRI) is the key whole‑body imaging technology for observing processes within a living object providing excellent resolution and contrast between soft tissues. In the present work, we exploited the non‑destructive properties of MRI to track longitudinally the dynamic changes that take place in developing pupae of the Empe...

Background and aims: Colour pattern is a key cue of bee attraction selectively driving the appeal of pollinators. It comprises the main colour of the flower with extra fine patterns indicating a reward focal point such as nectar, nectaries, pollen, stamens, and floral guides. Such definition of floral traits' advertisement guides visitation by the...

We present, for the first time, the spectral reflectance curves of bat-pollinated flowers using as model Ceiba glaziovii (Malvaceae), an impressive tree whose crown turns completely white during the reproductive season, and 13 other chiropterophilous species from Caatinga dry forest, Northeastern Brazil. Flowers from most species reflect light in t...

Blumen sind Kommunikationsstrukturen zwischen Blütenpflanzen und ihren Bestäubern. Dabei spielen visuelle Farbsignale eine herausragende Rolle. Da kein Bestäuber über ein dem Menschen ähnliches Farbsehsystem verfügt, beruht das Verstehen von Blumenfarben auf einer Analyse mit den Augen des betrachtenden Blütenbesuchers. Ultraviolettes Licht hat dab...

The evolution of floral traits in animal-pollinated plants involves the interaction between flowers as signal senders and pollinators as signal receivers. Flower colors are very diverse, effect pollinator attraction and flower foraging behavior, and are hypothesized to be shaped through pollinator-mediated selection. However, most of our current un...

A c c e p t e d M a n u s c r i p t 2  Background and Aims Colour pattern is a key cue of bee attraction selectively driving the appeal of pollinators. It comprises the main colour of the flower with extra fine patterns indicating a reward focal point such as nectar, nectaries, pollen, stamens, and floral guides. Such definition of floral traits'...

Colour signals of flowers facilitate detection, spontaneous preference, discrimination and flower constancy by important bee pollinators. At short distances bees orient to floral colour patterns to find a landing platform and collect nutrition, potentially improving the plants' reproductive success when multiple flowers are visited sequentially. In...

Specialization in nectarivory is an uncommon condition among bats, and it is restricted to two subfamilies of neotropical phyllostomids (Glossophaginae and Lonchophyllinae) which encompass dozens of bats with striking morpho‐physiological adaptations to exploit floral nectar (Muchhala and Tschapka 2020). Such bats commonly start the search for flow...

Visual floral characters play an important role in shaping plant-pollinator interactions. The genus Fritillaria L. (Liliaceae), comprising approximately 140 species, is described as displaying a remarkable variety of flower colours and sizes. Despite this variation in visual floral traits of fritillaries, little is known about the potential role of...

Zusammenfassung: Insekten unterscheiden sich in Körpergröße und Körperbau massiv von Säugetieren. Allein aufgrund der viel höheren Diversität – 6.500 Säugern stehen weit mehr als 1.000.000 Insektenarten gegenüber – sind bereits mehr spezielle Anpassungen bei Insekten zu erwarten. Insekten sind mit allen Sinnesleistungen ausgestattet, die auch bei S...

Plants invest floral resources, including nectar and pigment, with likely consequent reproductive costs. We hypothesized that plants, whose flowers abscise with age, reabsorb nectar and pigment before abscission. This was tested with flowers of Rhododendron decorum, which has large, conspicuous white flowers that increasingly abscise corollas as fl...

Little research has been conducted on the senses of sengis (elephant-shrews, Macroscelidea, Afrotheria, Mammalia); behavioural investigations about the animals' vision are completely missing. Other Afrotheria (manatees, elephants, tenrecs, rock hyraxes) are dichromats, having two types of cone photoreceptors in the retina. We tested the hypotheses...

Signals from flowers attract pollinators, usually with a mutualistic relationship giving reciprocal benefits. However, this relationship carries with it many pitfalls, including various kinds of deception in flowers and illegitimate visits of flower visitors or flower antagonists (van der Kooi et al., 2019). Flowers do not benefit from attracting a...

This article comments on: Zhe Chen, Yang Niu, Chang-Qiu Liu and Hang Sun, Red flowers differ in shades between pollination systems and across continents, Annals of Botany, Volume 126, Issue 5, 9 October 2020, Pages 837–848, https://doi.org/10.1093/aob/mcaa103

Under noiseless experimental conditions, sugar concentration of secreted floral nectar may increase after flower exposure to nearby sounds of pollinator flight (Veits et al. 2019). However, we reject the argument that this represents adaptive plant behaviour, and consider that the appealing analogy between a flower and human ear is unjustified.

Das Farbensehen des Menschen ist nicht mit dem Farbensehen von blütenbesuchenden Bienen zu vergleichen, denn Bienen können ultraviolettes Licht sehen, sind aber unempfindlich für rotes Licht. UV-Photos lassen spezielle, nur im UV sichtbare Muster auf Blüten erkennen. Durch den Vergleich mit Farbphotos gewinnt man eine Vorstellung, wie Bienen die Bl...

In social bees, the choice of food sources is based on several factors, including scent marks, color, and location of flowers. Here, we used similar setups, in which two stingless bee species, Melipona subnitida and Plebeia flavocincta, and the Western honeybee, Apis mellifera, were tested regarding the importance of chemical cues, color cues, and...

Nectar is the most common floral reward for flower-visiting flies, bees, bats and birds. Many flowers hide nectar in the floral tube and preclude sensing of nectar by flower-visitors from a distance. Even in those flowers that offer easily accessible nectar, the nectaries are mostly inconspicuous to the human eye and the amount of nectar is sparse....

The tropical Melastomataceae are characterized by poricidal anthers which constitute a floral filter selecting for buzz‐pollinating bees. Stamens are often dimorphic, sometimes with discernible feeding and pollinating functions. Rhynchanthera grandiflora produces nectarless flowers with four short stamens and one long stamen; all anthers feature a...

Heriades truncorum (Megachilidae) is a specialist bee that forages on Asteraceae and collects pollen by tapping its abdomen on pollen-presenting florets which places the grains directly in the ventral scopa. We tracked pollen transfer by female H. truncorum between conspecific inflorescences of Inula ensifolia and Pulicaria dysenterica by labelling...

Blütenpflanzen und Hummeln sind gleichermaßen aufeinander angewiesen. Hummeln benötigen den von den Blütenpfl anzen produzierten Pollen und Nektar für sich und ihre Larven und bestäuben die Blüten beim Sammeln der Blütennahrung. Hummeln reagieren auf verschiedene olfaktorische und optische Signale von Blütenpfl anzen, die sie dazu verleiten, bestim...

Like all animals, bees need to consume essential amino acids to maintain their body’s protein synthesis. Perception and discrimination of amino acids are, however, still poorly understood in bees (and insects in general). We used chemotactile conditioning of the proboscis extension response (PER) to examine (1) whether Bombus terrestris workers are...

The chive gnat, Bradysia odoriphaga, is a notorious pest of Allium species in China. Colour trapping is an established method for monitoring and control of Bradysia species. In order to clarify the effect of colour preference of B. odoriphaga for the perched substrate, multiple-choice tests were used to assess the response of the chive gnat to diff...

The randomness test of choice for chive gnat Bradysia odoriphaga at 4 chambers with same colour. (DOCX)

Bee-pollinated plants face a dilemma in that bees both passively transport pollen grains among conspecific flowers and actively collect pollen to feed their larvae. Therefore, mechanisms that reduce pollen collection by bees have evolved in melittophilous plants. Malvaceae pollen is uncollectable for corbiculate bees which has previously been ascri...

The chive gnat, Bradysia odoriphaga , is a notorious pest of Allium species in China. Colour trapping is an established method for monitoring and controlling of Bradysia species. In order to clarify the effect of colour preference of B. odoriphaga for the egg-laying substrate, multiple-choice tests were employed to assess the spontaneous response o...

Colour signals are the main floral trait for plant–pollinator communication. Owing to visual specificities, flower visitors exert different selective pressures on flower colour signals of plant communities. Although they evolved to attract pollinators, matching their visual sensitivity and colour preferences, floral signals may also evolve to avoid...

Zusammenfassung: In Wahlversuchen haben wir Hinweise dafür gewonnen, dass die Weibchen der Leuchtschabe Lucihormetica verrucosa Männchen mit roten Pronotumfl ecken, d.h. mit einem hohen Carotinoidgehalt der Epidermis, die unter der transparenten Pronotum-Cuticula liegt, attraktiver fi nden als Männchen mit weißen oder gelben Flecken, deren Epidermi...

Colour preferences and colour learning of the hoverfl y Eristalis tenax 27 Entomologie heute 30 (2018) Entomologie heute 30 (2018): 27-44 The Yellow Specialist: Colour Preferences and Colour Learning of the Hoverfly Eristalis tenax (Diptera: Syrphidae) Der Gelbspezialist: Farbpräferenzen und Farbenlernen der Schwebfliege Eristalis tenax (Diptera: S...

Bees use floral colour as a major long distance orientation cue. While it is known for bumblebees and honeybees that dominant wavelength (≙ colour hue), colour contrast and spectral purity (≙ saturation) are crucial for flower detection and discrimination, only little is known about colour preferences in stingless bees (Meliponini). In this experim...

Experimental setup. (TIF)

Semi-randomized order of dual choice tests. (UVB = UV-blue; B = blue; UVY = UV-yellow; Y = yellow; W = white; R = red; P+ = high spectral purity; P- = low spectral purity; I+ = high intensity; I- = low intensity; UV- = UV-absorbing; UV+ = UV-reflecting). (TIF)