Bill Hansson

• Professor
• Research Director at Max Planck Society

Interactions among insects, plants, and microorganisms are fundamental to ecosystem dynamics, with floral nectar and pollen serving as key resources for various organisms. Yeasts, such as Metschnikowia reukaufii, commonly found in nectar, influence nectarial attraction through volatile compounds (VOCs), yet the underlying biological mechanisms rema...

Many Drosophila species coexist by sharing their feeding and breeding sites, which may influence their oviposition choices in an interspecies social context. Whether and where to lay eggs is a crucial decision for female flies as it influences the success of their offspring, by minimizing the risk of predation, competition, or cannibalism. Signific...

The ability to tolerate otherwise toxic compounds can open up unique niches in nature. Among drosophilid flies, few examples of such adaptations are known and those which are known are typically from highly host-specific species. Here we show that the human commensal species Drosophila busckii uses dimethyldisulfide (DMDS) as a key mediator in its...

V-ATPases are ubiquitous and evolutionarily conserved rotatory proton pumps, which are crucial for maintaining various biological functions. Previous investigations have shown that a V-ATPase is present in the support cells of moth trichoid sensilla and influences their olfactory sensory neuron performance. Generally, V-ATPases are thought to regul...

V-ATPases are ubiquitous and evolutionarily conserved rotatory proton pumps, which are crucial for maintaining various biological functions. Previous investigations have shown that a V-ATPase is present in the support cells of moth trichoid sensilla and influences their olfactory sensory neuron performance. Generally, V-ATPases are thought to regul...

Background Insects detect odours using odorant receptors (ORs) expressed in olfactory sensory neurons (OSNs) in the antennae. Ecologically important odours are often detected by selective and abundant OSNs; hence, ORs with high antennal expression. However, little is known about the function of highly expressed ORs in beetles, since few ORs have be...

In insects, odorant receptors (ORs) are required for the detection of most olfactory cues. We investigated the function of a clade of four duplicated ORs in the hawkmoth Manduca sexta and found that these paralogs encode broadly tuned receptors with overlapping but distinct response spectra. Two paralogs, which arose after divergence from a related...

Volatile aroma compounds are important chemical cues for insects. Behavioral responses to specific odors differ strongly between insect species, and the exact causative molecules are often unknown. Beer is frequently used in insect traps because it combines hundreds of plant and microbial aromas that attract many insects. Here, we analyzed response...

Drosophila species belonging to the virilis group offer a unique opportunity for studying olfactory adaptations necessary for survival within forest ecosystems as many of these species breed within decaying plant vascular tissues. However, the knowledge regarding olfactory preferences within their ecological niche is extremely limited. Here, we foc...

Sex pheromones play a crucial role in species recognition and reproductive isolation. Despite being largely species-specific in drosophilids, the mechanisms underlying pheromone detection, production, and their influence on mating behavior remain poorly understood. Here, we compare the chemical profiles of Drosophila bipectinata and D. melanogaster...

In birds and insects, the female uptakes sperm for a specific duration post-copulation known as the ejaculate holding period (EHP) before expelling unused sperm and the mating plug through sperm ejection. In this study, we found that Drosophila melanogaster females shortens the EHP when incubated with males or mated females shortly after the first...

Variation in sex pheromones is regarded as one of the causes of reproductive isolation and speciation. We recently identified 51 male- and female-specific compounds – many of which function as sex pheromones – in 99 drosophilid species [1]. Here, we report that despite many of these compounds being shared between species, their quantities differ si...

An essential adaptive strategy in insects is the evolution of olfactory receptors (ORs) to recognize important volatile environmental chemical cues. Our model species, Ceratosolen fusciceps , a specialist wasp pollinator of Ficus racemosa , likely possesses an OR repertoire that allows it to distinguish fig‐specific volatiles in highly variable env...

Odor detection in insects is largely mediated by structures on antennae called sensilla, which feature a strongly conserved architecture and repertoire of olfactory sensory neurons (OSNs) and various support cell types. In Drosophila, OSNs are tightly apposed to supporting cells, whose connection with neurons and functional roles in odor detection...

In birds and insects, the female uptakes sperm for a specific duration post-copulation known as the ejaculate holding period (EHP) before expelling unused sperm and the mating plug through sperm ejection. In this study, we found that Drosophila melanogaster females shortens the EHP when incubated with males or mated females shortly after the first...

Plant-produced volatiles play a pivotal role as mediators in complex interactions between insects and plants. Despite the widespread recognition that these compounds serve as cues for herbivorous insects to locate their preferred host plants, their effects on insect mating behavior are less understood. Here, we show that male oriental fruit flies (...

In a world grappling with climate change, understanding the enduring impact of changes in temperatures on insect adult traits is crucial. It is proposed that cold-and warm-adapted species exhibit specialized behavioural and physiological responses to their respective temperature ranges. In contrast, generalist species maintain more stable metabolic...

Little is known about the blood‐feeding physiology of arbovirus vector Aedes aegypti although this type of mosquito is known to transmit infectious diseases dengue, Zika, yellow fever, and chikungunya. Blood feeding in the female A. aegypti mosquito is essential for egg maturation and for transmission of disease agents between human subjects. Here,...

Background Accurate detection of pheromones is crucial for chemical communication and reproduction in insects. In holometabolous flies and moths, the sensory neuron membrane protein 1 (SNMP1) is essential for detecting long-chain aliphatic pheromones by olfactory neurons. However, its function in hemimetabolous insects and its role for detecting ph...

Learning, memorizing, and recalling of potential ovipositing sites can influence oviposition preference. Classical conditioning experiments have shown that vinegar flies can learn the association of olfactory, gustatory, or visual stimuli with either positive or negative unconditioned stimuli. However, less is known about whether similar associatio...

In insect olfaction, sensitization refers to the amplification of a weak olfactory signal when the stimulus is repeated within a specific time window. In the vinegar fly, Drosophila melanogaster, this occurs already at the periphery, at the level of olfactory sensory neurons (OSNs) located in the antenna. In our study, we investigate whether sensit...

Variation in sex pheromones is regarded as one of the causes of reproductive isolation and speciation. We recently identified 51 male- and female-specific compounds – many of which function as sex pheromones – in 99 drosophilid species ¹ . Here, we report that despite many of these compounds being shared between species, their quantities differ sig...

In birds and insects, females uptake sperm for a specific duration post-copulation known as the ejaculate holding period (EHP) before expelling unused sperm and the mating plug through sperm ejection. Our study uncovered that encountering males or mated females after mating substantially shortens EHP, a phenomenon we term ‘ m ale-induced E HP s hor...

In birds and insects, females uptake sperm for a specific duration post-copulation known as the ejaculate holding period (EHP) before expelling unused sperm and the mating plug through sperm ejection. Our study uncovered that encountering males or mated females after mating substantially shortens EHP, a phenomenon we term ‘ m ale-induced E HP s hor...

Where to lay the eggs is a crucial decision for females as it influences the success of their offspring. Female flies prefer to lay eggs on food already occupied and consumed by larvae, which facilitates social feeding, but potentially could also lead to detrimental interactions between species. Whether females can modulate their attraction to cues...

Animals employ different strategies to establish mating boundaries between closely related species, with sex pheromones often playing a crucial role in identifying conspecific mates. Many of these pheromones have carbon-carbon double bonds, making them vulnerable to oxidation by certain atmospheric oxidant pollutants, including ozone. Here, we inve...

The ability to tolerate otherwise toxic compounds can open up unique niches in nature. Among drosophilid flies few examples of such adaptations are known and then typically from highly host specific species. Here we show that the human commensal Drosophila busckii uses dimethyldisulfide (DMDS) as a key mediator in its host selection. Despite DMDS's...

Female herbivorous insects are expected to oviposit on the host plant providing the best performance of the offspring. However, in some insects the larvae are mobile and are not totally dependent on the mother's choice. They can change host plant when conditions for development or exposure to natural enemies vary between individual plants within a...

The search for resources occupies a major part of the time and energy budget of many insects. In this context, many insects display constancy behavior, in which they learn to return to the same, predictably rewarding resource repeatedly. Flower constancy is one such behavior, where nectar-feeding insects restrict foraging visits to a few plant spec...

In a world grappling with climate change, understanding the enduring impact of changes in temperature on insect adult traits is crucial. Here, we explored the intricate dynamics of exposure to different temperatures in three Drosophila species: Drosophila ezoana originating in Arctic regions, D. novamexicana in arid, hot environments, and in the co...

In the silkmoth Bombyx mori, the role of male sensilla trichodea in pheromone detection is well established. Here we study the corresponding female sensilla, which contain two olfactory sensory neurons (OSNs) and come in two lengths, each representing a single physiological type. Only OSNs in medium trichoids respond to the scent of mulberry, the s...

Article Odorant detection in a locust exhibits unusually low redundancy Highlights d The migratory locust emits sex-, phase-, and developmental-stage-related odorants d The response to odorants depends on sex, phase, and stage of the behaving animal d To detect these odorants, locusts use narrowly tuned odorant receptors

Background. Insects detect odours using odorant receptors (ORs) expressed in olfactory sensory neurons (OSNs) in the antennae. Odours important to fitness are believed to be detected by selective and abundant OSNs; hence, ORs with high antennal expression. However, little is known about the function of highly expressed ORs in beetles, since few ORs...

Background. Insects detect odours using odorant receptors (ORs) expressed in olfactory sensory neurons (OSNs) in the antennae. Ecologically important odours are often detected by selective and abundant OSNs; hence, ORs with high antennal expression. However, little is known about the function of highly expressed ORs in beetles, since few ORs have b...

In birds and insects, females uptake sperm for a specific duration post-copulation known as the ejaculate holding period (EHP) before expelling unused sperm and the mating plug through sperm ejection. Our study uncovered that encountering males or mated females after mating substantially shortens EHP, a phenomenon we term ‘ m ale-induced E HP s hor...

Swarming locusts cause huge plagues across the world threatening food production. Before swarms form, locust populations exhibit a dramatic phase change from a solitary to a gregarious phase. The cause of this phase change is a complicated interplay of conspecific and environmental cues and is, especially for one of the major pests, the migratory l...

Olfaction is a fundamental sense guiding animals to their food. How the olfactory system evolves and influences behavior is still poorly understood. Here, we selected five drosophilid species, including Drosophila melanogaster, inhabiting different ecological niches to compare their olfactory systems at multiple levels. We first identified ecologic...

Behavior is often categorized as being innate or learned, with the specific circuits being assigned to one of these categories. In Drosophila, neural circuits mediating an innate behavioral response are considered as being 'hard-wired', as activation of these neuronal pathways leads to stereotyped behaviors. However, only a limited number of studie...

Rapid and ongoing climate change increases global temperature, impacts feeding, and reproduction in insects. The olfaction plays an important underlying role in these behaviors in most insect species. Here, we investigated how changing temperatures affect odor detection and ensuing behavior in three drosophilid flies: Drosophila novamexicana, D. vi...

In the Drosophila olfactory system most odorants are encoded in the antennal lobe in a combinatory way, activating several glomerular circuits. However, odorants of particular ecological role for the fly are encoded through activation of a single specialized olfactory pathway. Comparative analyses of densely reconstructed connectomes of one broadly...

Drosophila melanogaster encounters a variety of odor cues signaling potentially harmful threats through-out its life, which are detected by highly specialized olfactory circuits enabling the animal to avoid them. We studied whether such crucial neuronal pathways are hard-wired or can be modulated by experience. Using long-term exposure to high conc...

Olfaction is a crucial sensory modality in insects and is underpinned by odor-sensitive sensory neurons expressing odorant receptors that function in the dendrites as odorant-gated ion channels. Along with expression, trafficking, and receptor complexing, the regulation of odorant receptor function is paramount to ensure the extraordinary sensory a...

Insects perceive countless odors with the help of odorant receptors (ORs) expressed by olfactory sensory neurons (OSNs). OR complexes are composed of odor-specific proteins OrX and olfactory co-receptor proteins Orco, with both extracellular C-terminus and intracellular N-terminus. Here, we generated a genetically modified Drosophila melanogaster f...

Many animals engage in cannibalism to supplement their diets. Among dense populations of migratory locusts, cannibalism is prevalent. We show that under crowded conditions, locusts produce an anticannibalistic pheromone called phenylacetonitrile. Both the degree of cannibalism and the production of phenylacetonitrile are density dependent and covar...

Ticks are important vectors of many pathogens with tremendous impact on human and animal health. Studies of semiochemical interactions and mechanisms underlying chemoreception can provide important tools in tick management. Niemann-Pick type C2 (NPC2) proteins have been proposed as one type of chemoreceptor in arthropods. Here, we cloned two NPC2 g...

Rapid and ongoing climate change increases global temperature and impacts both feeding and reproduction in insects. The sense of smell plays an important underlying role in these behaviors in most insect species. Here, we aimed to investigate how changing temperatures affect odor detection and ensuing behavior in three drosophilid flies: Drosophila...

In a heterogeneous and changing environment, oviposition site selection strongly affects the survival and fitness of the offspring.1,2 Similarly, competition between larvae affects their prospects.3 However, little is known about the involvement of pheromones in regulating these processes.4,5,6,7,8 Here, we show that mated females of Drosophila mel...

Introduction: The striped ambrosia beetle Trypodendron lineatum (Coleoptera, Curculionidae, Scolytinae) is a major forest pest in the Holarctic region. It uses an aggregation pheromone and host and non-host volatiles to locate suitable host trees, primarily stressed or dying conifer trees. The beetles bore into the xylem and inoculate spores of the...

Insect sexual communication often relies upon sex pheromones. Most insect pheromones, however, contain carbon-carbon double bonds and potentially degrade by oxidation. Here, we show that frequently reported increased levels of Anthropocenic ozone can oxidize all described male-specific pheromones of Drosophila melanogaster, resulting in reduced amo...

An essential adaptive strategy in insects is the evolution of olfactory receptors (ORs) to recognize important volatile environmental chemical cues. Our model species, Ceratosolen fusciceps, a specialist wasp pollinator of Ficus racemosa , likely possesses an OR repertoire that allows it to distinguish fig-specific volatiles in highly variable envi...

Dietary composition affects food preference in animals. High sugar intake suppresses sweet sensation from insects to humans, but the molecular basis of this suppression is largely unknown. Here, we reveal that sugar intake in Drosophila induces the gut to express and secrete Hedgehog ( Hh ) into the circulation. We show that the midgut secreted Hh...

Animals form sensory associations and store them as memories to guide behavioral decisions. Although unimodal learning has been studied extensively in insects, it is important to explore sensory cues in combination, since most behaviors require multimodal inputs. In our study, we optimized the T-maze to employ both visual and olfactory cues in a cl...

To manage the great complexity of detecting and identifying olfactory cues, the insect olfactory system has evolved two main strategies: combinatorial coding and specialized, narrowly tuned olfactory pathways. In combinatorial coding, odorants are encoded by activation of multiple, broadly tuned olfactory sensory neurons that innervate distinct set...

Chemosensation is essential for the survival of insects. Activities like searching for food, mating, and oviposition in the fruit fly, Drosophila melanogaster are to a great extent governed by chemical cues detected via olfaction and gustation. This chemical information is conveyed to higher brain centers via populations of diverse olfactory sensor...

Insect sexual communication often relies upon sex pheromones1-3. Most insect pheromones, however, contain carbon-carbon double bonds and potentially degrade by oxidation4. Here, we show that already frequently reported increased levels of Anthropocenic ozone can oxidize all described male-specific pheromones of Drosophila melanogaster5-7, resulting...

For the nocturnal hawkmoth Manduca sexta, olfactory and gustatory cues are essential for finding partners, food, and oviposition sites. Three chemosensory receptor families, odorant receptors (ORs), ionotropic receptors (IRs), and gustatory receptors (GRs) are involved in the detection of these stimuli. While many chemosensory receptor genes have b...

Insects rely heavily on sampling information from their environment for survival and fitness. Different sensory channels with dedicated downstream neural substrates are programmed to fine tune these signals and translate them into usable instructions to mediate complex behaviors. Sensory information can also be learned and stored as memories that i...

Chemosensation is essential for the survival of insects. Activities like searching for food, mating, and oviposition in the fruit fly, Drosophila melanogaster are to a great extent governed by chemical cues detected via olfaction and gustation. This chemical information is conveyed to higher brain centres via populations of diverse olfactory sensor...

Many animals engage in cannibalism to supplement their diets. In swarms of migratory locusts, cannibalism is prevalent and thought to be an important factor for swarm dynamics. We show that in dense swarms, locusts defend themselves by producing an anti-cannibalistic pheromone; phenylacetonitrile (PAN). Both the degree of cannibalism and the produc...

Olfactory coding, from insects to humans, is canonically considered to involve considerable across-fiber coding already at the peripheral level, thereby allowing recognition of very large numbers of odor compounds. Here we show that the migratory locust, Locusta migratoria , has evolved an alternative strategy built on highly specific odorant recep...

Understanding neuronal representations of odor-evoked activities and their progressive transformation from the sensory level to higher brain centers features one of the major aims in olfactory neuroscience. Here, we investigated how odor information is transformed and represented in higher-order neurons of the lateral horn, one of the higher olfact...

The sense of smell is pivotal for nocturnal moths to locate feeding and oviposition sites. However, these crucial resources are often rare and their bouquets are intermingled with volatiles emanating from surrounding ‘background’ plants. Here, we asked if the olfactory system of female hawkmoths, Manduca sexta , could differentiate between crucial...

Insects are able to detect a plethora of olfactory cues using a divergent family of odorant receptors (ORs). Despite the divergent nature of this family, related species frequently express several evolutionarily conserved OR orthologues. In the largest order of insects, Coleoptera, it remains unknown whether OR orthologues have conserved or diverge...

Despite their comparatively small brains, insects are able to survive and thrive in their environment. In the past, it was thought that insects are driven mainly by their instincts. However, today it is well established that they possess unique abilities to learn and use their experience in future decisions. Like many higher animals insects are abl...

Comparative analyses of multiple genomes are used extensively to examine the gains and losses of chemosensory receptors across the genus Drosophila. However, few studies have delved into functional olfactory characteristics. Here we assess olfactory function across 20 species, and identify and describe several similar elements of evolution. We docu...

The planet is presently undergoing dramatic changes caused by human activities. We are living in the era of the Anthropocene, where our activities directly affect all living organisms on Earth. Insects constitute a major part of the world’s biodiversity and currently, we see dwindling insect biomass but also outbreaks of certain populations. Most i...

[This corrects the article DOI: 10.1371/journal.pntd.0009098.].

Insects detect volatile chemosignals with olfactory sensory neurons (OSNs) that express olfactory receptors. Among them, the most sensitive receptors are the odorant receptors (ORs), which form cation channels passing Ca2+. OSNs expressing different groups of ORs show varying optimal odor concentration ranges according to environmental needs. Certa...

Insects decode volatile chemical signals from its surrounding environment with the help of its olfactory system, in a fast and reliable manner for its survival. In order to accomplish this task, odorant receptors (ORs) expressed in olfactory sensory neurons (OSNs) in the fly’s antenna process such odor information. In order to study such a sophisti...

Insects are able to detect a plethora of olfactory cues in the environment using a divergent family of odorant receptors (ORs). Despite the divergent nature of this family, related species frequently express several evolutionarily conserved OR orthologues. In Coleoptera, it remains unknown whether OR orthologues have conserved or divergent function...

The sense of smell is pivotal for nocturnal moths to locate feeding and oviposition sites. However, these crucial resources are often rare and their bouquets are intermingled with volatiles emanating from surrounding ‘background’ plants. Here we asked if the olfactory system of female hawkmoths, Manduca sexta , could differentiate between crucial a...

In nature, plant-insect interactions occur in complex settings involving multiple trophic levels, often with multiple species at each level.¹ Herbivore attack of a host plant typically dramatically alters the plant’s odor emission in terms of concentration and composition.²,³ Therefore, a well-adapted herbivore should be able to predict whether a p...

In this review, we highlight sources of alcohols in nature, as well as the behavioral and ecological roles that these fermentation cues play in the short lifespan of Drosophila melanogaster. With a focus on neuroethology, we describe the olfactory detection of alcohol as well as ensuing neural signaling within the brain of the fly. We proceed to ex...

Insects detect volatile chemicals using antennae, which house a vast variety of olfactory sensory neurons (OSNs) that innervate hair-like structures called sensilla where odor detection takes place. In addition to OSNs, the antenna also hosts various support cell types. These include the triad of trichogen, tormogen, and thecogen support cells that...

In insect olfaction, sensitization refers to the amplification of a weak olfactory signal when the stimulus is repeated within a specific time window. In the vinegar fly, Drosophila melanogaster , his occurs already at the periphery, at the level of olfactory sensory neurons (OSNs) located in the antenna. In our study, we investigate whether sensit...

Many pollinating insects exhibit flower constancy, i.e. they target flower species they have already experienced and fed from. While the insects might profit from reduced handling costs when revisiting similar flowers, flower constancy, in addition, is of benefit for the plants as it guarantees pollen transfer to conspecifics. Here we investigate w...

Triatomine bugs are the blood feeding insect vectors transmitting Chagas disease to humans, a neglected tropical disease that affects over 8 million people, mainly in Latin America. The behavioral responses to host cues and bug signals in Rhodnius prolixus are state dependent, i.e., they vary as a function of post-ecdysis age. At the molecular leve...

The primary olfactory centres of metazoans as diverse as arthropods and mammals consist of an array of fields of dense synaptic neuropil, the olfactory glomeruli. However, the neurochemical structure of crustacean olfactory glomeruli is largely understudied when compared to the insects. We analysed the glomerular architecture in selected species of...

Insects detect volatile chemicals using antennae, which house a vast variety of olfactory sensory neurons (OSNs) that innervate hair-like structures called sensilla where odor detection takes place. In addition to OSNs, the antenna also hosts various support cell types. These include the triad of trichogen, tormogen and thecogen support cells that...