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Dipteran or “true” flies occupy nearly every terrestrial habitat, and have evolved to feed upon a wide variety of sources including fruit, pollen, decomposing animal matter, and even vertebrate blood. Here we analyze the molecular, genetic and cellular basis of odor response in the tsetse fly Glossina morsitans, which feeds on the blood of humans and their livestock, and is a vector of deadly trypanosomes. The G. morsitans antenna contains specialized subtypes of sensilla, some of which line a sensory pit not found in the fruit fly Drosophila. We characterize distinct patterns of G. morsitans Odor receptor (GmmOr) gene expression in the antenna. We devise a new version of the “empty neuron” heterologous expression system, and use it to functionally express several GmmOrs in a mutant olfactory receptor neuron (ORN) of Drosophila. GmmOr35 responds to 1-hexen-3-ol, an odorant found in human emanations, and also alpha-pinene, a compound produced by malarial parasites. Another receptor, GmmOr9, which is expressed in the sensory pit, responds to acetone, 2-butanone and 2-propanol. We confirm by electrophysiological recording that neurons of the sensory pit respond to these odorants. Acetone and 2-butanone are strong attractants long used in the field to trap tsetse. We find that 2-propanol is also an attractant for both G. morsitans and the related species G. fuscipes, a major vector of African sleeping sickness. The results identify 2-propanol as a candidate for an environmentally friendly and practical tsetse attractant. Taken together, this work characterizes the olfactory system of a highly distinct kind of fly, and it provides an approach to identifying new agents for controlling the fly and the devastating diseases that it carries. [ABSTRACT FROM AUTHOR]

Dipterans, especially the sarcosaprophagous communities are of substantial importance from medical, veterinary and forensic entomological perspectives. Muscids are generally seen to colonize carcasses at advanced stages of decomposition when the initial dominance of calliphorids and sarcophagids subsides. Ophyra capensis (Wiedemann, 1818), a muscid fly with a relatively wide distribution range is considered of decent forensic relevance as it has been reported not only from cadavers placed outdoors but also from graves and exhumed corpses. The prime objective of the present study is to analyse and interpret the ultrastructural morphology of three sensory organs, namely, the ocellar region, compound eye and antenna of adult male and female Ophyra capensis with the help of scanning electron microscopy, so as to facilitate accurate morphological identification of the species in forensic entomological investigations. SEM analysis of the ocellar region revealed that it was larger in size in females and covered with microtrichia. Ultrastructural analysis of the compound eye indicated that the antero-frontally located ommatidia were larger in size in comparison to the rest of the facets, along with notable sexual dimorphism regarding the size of the ommatidia. The ultrastructure of the antenna displayed the presence of five types of sensilla, two types of chaetic sensilla on the scape and pedicel; trichoid sensilla and two types of basiconic sensilla on the flagellum along with numerous microtrichia. Both types of basiconic sensilla displayed a multiporous surface indicating their characteristic olfactory function. The morphological characteristics of these sensilla along with their probable functions are discussed in greater details. [ABSTRACT FROM AUTHOR]

Insects have acquired excellent sensory information processing abilities in the process of evolution. In addition, insects have developed communication schemes based on the temporal patterns of specific sensory signals. For instance, male moths approach a female by detecting the spatiotemporal pattern of a pheromone plume released by the female. Male crickets attract a conspecific female as a mating partner using calling songs with species-specific temporal patterns. The dance communication of honeybees relies on a unique temporal pattern of vibration caused by wingbeats during the dance. Underlying these behaviors, neural circuits involving inhibitory connections play a critical common role in processing the exact timing of the signals in the primary sensory centers of the brain. Here, we discuss common mechanisms for processing the temporal patterns of sensory signals in the insect brain. [ABSTRACT FROM AUTHOR]

Flying insects routinely forage in complex and cluttered sensory environments. Their search for a food or a pheromone source typically begins with a whiff of odor, which triggers a flight response, eventually bringing the insect near the odor source. However, pinpointing the precise location of an odor source requires use of both visual and olfactory modalities, aided by odor plumes. Here, we investigated odortracking behavior in fruit flies (Drosophila melanogaster) presentedwith low- or high-contrast visual landmarks, either paired with or separate from an attractive odor cue. These experiments were conducted either in a gentle air stream which generated laminar odor plumes or in still air in which odor dissipates uniformly in all directions. Trajectories of flies revealed several novel features of their odor-tracking behavior in addition to those previously documented. First, in both moving and still air, odor-seeking flies rely on the co-occurrence of visual landmarks with olfactory cues to guide them to odorant objects. Second, flies abruptly decelerate upon encountering an odor plume, thereafter steering towards the nearest visual objects that had no inherent salience in the absence of odor. Thus, interception of an attractive odor increases their salience to nearby high-contrast visual landmarks. Third, flies adopt distinct odor-tracking strategies during flight inmoving versus still air. Whereas they weave in and out of plumes towards an odor source in airflow, theirapproach ismore incremental in still air. Both strategies are robust and flexible, and enable flies to reliably find odor sources under diverse visual and airflow environments. [ABSTRACT FROM AUTHOR]

Social insects may have morphologically and behaviorally specialized workers that vary in requirements for sensory information processing, making them excellent systems to examine the relationship between brain structure and behavior. The density and size of synaptic complexes (microglomeruli, MG) in the mushroom bodies (MB) have served as proxies for processing ability and synaptic plasticity, and have been shown to vary among insect species that differ in behavioral complexity. To understand the relationship between behavioral specialization and synaptic structure, we examined age-related changes in MG density and size between minor worker and soldier subcastes in two species of Pheidole ants, P. dentata and P. morrisi, that differ in behavior. We hypothesized that task-diverse minor workers would have more densely packed MG than soldiers, and that species-specific differences in soldier repertories would be reflected in MG structure. We also examined MG variation in young and mature minor workers and soldiers, predicting that as workers age and develop behaviorally, MG would decrease in density in both subcastes due to synaptic pruning. Results support the hypothesis that MG density in the lip (olfactory) and collar (visual) regions of the MBs decrease with age in association with increases in bouton size in the lip. However, minors had significantly lower densities of MG in the lip than soldiers, suggesting MG may not show structural variation according to subcaste-related differences in cognitive demands in either species. [ABSTRACT FROM AUTHOR]

1. Much is known about how enriched environmental diversity affects ability to learn across the months and years that are the developmental periods of large animals. 2. Less is known about how diversity impacts learning across the minutes and hours during which sensory environments of small foraging animals such as insects may vary dramatically. 3. This study shows that Drosophila melanogaster exposed to a diversity of odour-taste associations over a few minutes subsequently learn standard associative learning tasks poorly. 4. This effect is robust to variation in odours used in all parts of experiments. 5. Findings may have an impact on at least three major research areas in ecology: the relationship between biodiversity and ecosystem functioning; the evolution of floral constancy in pollinators; and the pest-protective effects of mixed species crops. [ABSTRACT FROM AUTHOR]

Tea grey geometrid (Ectropis grisescens), a devastating chewing pest in tea plantations throughout China, produces Type-II pheromone components. Little is known about the genes encoding proteins involved in the perception of Type-II sex pheromone components. To investigate the olfaction genes involved in E. grisescens sex pheromones and plant volatiles perception, we sequenced female and male antennae transcriptomes of E. grisescens. After assembly and annotation, we identified 153 candidate chemoreception genes in E. grisescens, including 40 odorant-binding proteins (OBPs), 30 chemosensory proteins (CSPs), 59 odorant receptors (ORs), and 24 ionotropic receptors (IRs). The results of phylogenetic, qPCR, and mRNA abundance analyses suggested that three candidate pheromone-binding proteins (EgriOBP2, 3, and 25), two candidate general odorant-binding proteins (EgriOBP1 and 29), six pheromone receptors (EgriOR24, 25, 28, 31, 37, and 44), and EgriCSP8 may be involved in the detection of Type-II sex pheromone components. Functional investigation by heterologous expression in Xenopus oocytes revealed that EgriOR31 was robustly tuned to the E. grisescens sex pheromone component (Z,Z,Z)-3,6,9-octadecatriene and weakly to the other sex pheromone component (Z,Z)-3,9-6,7-epoxyoctadecadiene. Our results represent a systematic functional analysis of the molecular mechanism of olfaction perception in E. grisescens with an emphasis on gene encoding proteins involved in perception of Type-II sex pheromones, and provide information that will be relevant to other Lepidoptera species. [ABSTRACT FROM AUTHOR]

Background: The Asian tiger mosquito Aedes albopictus is a highly invasive species and competent vector of several arboviruses (e.g. dengue, chikungunya, Zika) and parasites (e.g. dirofilaria) of public health importance. Compared to other mosquito species, Ae. albopictus females exhibit a generalist host seeking as well as a very aggressive biting behaviour that are responsible for its high degree of nuisance. Several complex mosquito behaviours such as host seeking, feeding, mating or oviposition rely on olfactory stimuli that target a range of sensory neurons localized mainly on specialized head appendages such as antennae, maxillary palps and the mouthparts. Results: With the aim to describe the Ae. albopictus olfactory repertoire we have used RNA-seq to reveal the transcriptome profiles of female antennae and maxillary palps. Male heads and whole female bodies were employed as reference for differential expression analysis. The relative transcript abundance within each tissue (TPM, transcripts per kilobase per million) and the pairwise differential abundance in the different tissues (fold change values and false discovery rates) were evaluated. Contigs upregulated in the antennae (620) and maxillary palps (268) were identified and relative GO and PFAM enrichment profiles analysed. Chemosensory genes were described: overall, 77 odorant binding proteins (OBP), 82 odorant receptors (OR), 60 ionotropic receptors (IR) and 30 gustatory receptors (GR) were identified by comparative genomics and transcriptomics. In addition, orthologs of genes expressed in the female/male maxillary palps and/or antennae and involved in thermosensation (e.g. pyrexia and arrestin1), mechanosensation (e.g. piezo and painless) and neuromodulation were classified. Conclusions: We provide here the first detailed transcriptome of the main Ae. albopictus sensory appendages, i.e. antennae and maxillary palps. A deeper knowledge of the olfactory repertoire of the tiger mosquito will help to better understand its biology and may pave the way to design new attractants/repellents. [ABSTRACT FROM AUTHOR]

Drosophila suzukii Matsumura ( Diptera: Drosophilidae), also known as the spotted-wing drosophila, is a global pest fly. The degree of infestation of D. suzukii varies greatly among host plants, possibly depending on the physical properties of the fruits. Because some of the physical properties of fruits can only be judged by touching them, D. suzukii may choose to oviposit based on the physical properties of fruits and remote sensory information such as visual cues. Here, we conducted associative learning experiments with artificial substrates consisting of water, cornmeal, fructose, and agarose with different colors and firmness. We assessed associative learning by conditioning flies with combinations of two colors (purple or green) and degrees of firmness (firm or soft), and comparing their choice between the conditioned color and the other color afterward. We demonstrated that D. suzukii had an associative learning ability but it was limited to the association between green and soft. Drosophila suzukii conditioned with green and soft substrate preferred green as the first choice in the test phase. The proximate cause of this asymmetrical associative learning ability is completely unknown, but the pattern of learning coincides with D. suzukii's preference for immature fruits on the tree in nature, possibly to avoid competition with other fruit flies. The associative learning ability of D. suzukii was found to be limited to a certain combination of color and firmness. It suggests that the asymmetrical association of the natural fruit color and physical properties played a role in the evolution of color-specific associative learning ability of D. suzukii. [ABSTRACT FROM AUTHOR]

Anoplophora glabripennis has a complex suite of mate-finding behaviors, the functions of which are not entirely understood. These behaviors are elicited by a number of factors, including visual and chemical cues. Chemical cues include a male-produced volatile semiochemical acting as a long-range sex pheromone, a female-produced cuticular hydrocarbon blend serving as a sex-identification contact pheromone, and a recently identified female-produced trail sex pheromone that is followed by mate-seeking males. However, the sensory appendages and sensilla on these appendages used to detect the trail sex pheromone are unknown. We evaluated the ability of virgin male A. glabripennis to follow a sex pheromone trail after removal of the terminal four antennal segments and/or the maxillary and labial palps using a two-choice behavioral bioassay. We also tested the ability of males to follow the trail sex pheromone using volatile pheromone cues only, without physical contact with the pheromone. Results indicate that the palps are primarily responsible for sensing the pheromone, with males lacking palps unable to respond behaviorally to the trail sex pheromone. Under the conditions of this study, males could not follow the sex pheromone trail without direct contact, suggesting that olfaction may not be involved in detection of this pheromone. However, we did not determine to what degree the trail pheromone chemicals can volatilize under our experimental conditions. This work is important in elucidating the behaviors and sensory structures involved in mate-finding by this species on host trees, and these studies may help determine whether the trail sex pheromone has applications for monitoring and management. [ABSTRACT FROM AUTHOR]

Sound localization in insects is typically investigated using single loudspeaker paradigms to examine the impact of sensory cues. Here, the contribution of specific cues to turning responses in a two-loudspeaker paradigm equivalent to a choice situation was examined. For that, several sensory cues were systematically varied to determine their respective contribution to the strength of the turning response in female crickets. In three experimental sets (1) the temporal arrangement of chirp patterns broadcast from two speakers, (2) the relative timing of chirps and (3) the impact of phase differences of the carrier frequency were varied at different intensity levels between both speakers. While the arrangement of chirp patterns had little influence on the strength of turning responses, time delays up to 20 ms and phase differences of 90° and 270° clearly affected directional turning at otherwise equal intensities. In all three sets of experiments turning responses were sensitive to intensity differences and saturated at +/− 6 dB. Turning responses due to timing of pulses or phase differences were compensated by intensity differences of 2-3 dB. Building on a large body of literature on peripheral and central processing it was possible to assign the observed effects to specific processing stages in the auditory pathway of crickets. [ABSTRACT FROM AUTHOR]

Stingless bees (Hymenoptera, Apidae, Meliponini) are by far the largest group of eusocial bees on Earth. Due to the diversity of evolutionary responses to specific ecological challenges, the Meliponini are well suited for comparative studies of the various adaptations to the environment found in highly eusocial bees. Of particular interest are the physiological mechanisms underlying the sophisticated cooperative and collective actions of entire colonies, which form the basis of the ecological success of the different bee species under the particular conditions prevailing in their respective environment. The present Special Issue of the Journal of Comparative Physiology A provides a sample of the exciting diversity of sensorial and behavioral adaptations in stingless bees, particularly concerning (1) the sensory bases for foraging, (2) chemical communication, and (3) the behavioral ecology of foraging. [ABSTRACT FROM AUTHOR]

The morphology of larvae of Dielocroce ephemera (Gerstaecker, 1894) is described and figured for the first time using light and scanning electron microscopy. The females were collected from Mardin Province, Turkey, and maintained in the laboratory. The different parts of the third instar larvae such as head, mandibles, antennae and types of sensory receptors are described and illustrated. [ABSTRACT FROM AUTHOR]

In fruit flies Drosophila melanogaster, environmental cycles of light and temperature are known to influence behavioral rhythms through dedicated sensory receptors. But the thermosensory pathways and molecular receptors by which thermal cycles modulate locomotor activity rhythms remain unclear. Here, we report that neurons expressing warmth-activated ion channel Drosophila Transient Receptor Potential-A1 (dTRPA1) modulate distinct aspects of the rhythmic activity/rest rhythm in a light-dependent manner. Under light/dark (LD) cycles paired with constantly warm ambient conditions, flies deficient in dTRPA1 expression are unable to phase morning and evening activity bouts appropriately. Correspondingly, we show that electrical activity of a few neurons targeted by the dTRPA1SH-GAL4 driver modulates temperature-dependent phasing of activity/rest rhythm under LD cycles. The expression of dTRPA1 also affects behavior responses to temperature cycles combined with constant dark (DD) or light (LL) conditions. We demonstrate that the mid-day “siesta” exhibited by flies under temperature cycles in DD is dependent on dTRPA1 expression in a small number of neurons that include thermosensory anterior cell neurons. Although a small subset of circadian pacemaker neurons may express dTRPA1, we show that CRY-negative dTRPA1SH-GAL4 driven neurons are critical for the suppression of mid-thermophase activity, thus enabling flies to exhibit siesta. In contrast to temperature cycles in DD, under LL, dTRPA1 is not required for exhibiting siesta but is important for phasing of evening peak. Our studies show that activity/rest rhythms are modulated in a temperature-dependent manner via signals from dTRPA1SH-GAL4 driven neurons. Taken together, these results emphasize the differential influence of thermoreceptors on rhythmic behavior in fruit flies in coordination with light inputs. [ABSTRACT FROM AUTHOR]

Thermosensation is critically important for survival of all animals. In the cockroach Periplaneta americana, thermoreceptor neurons on antennae and thermosensory interneurons in the antennal lobe have been characterized electrophysiologically, and recent studies using advanced transgenic technologies in the fruit fly Drosophila melanogaster have added much to the knowledge of these neurons, enabling us to discuss common principles of thermosensory processing systems in insects. Cockroaches and many other insects possess only one type of thermoreceptor neurons on antennae that are excited by cooling and inhibited by warming. In contrast, the antennae of fruit flies and other dipterans possess oppositely responding warm and cold receptor neurons. Despite differences in their thermoreceptive equipment, central processing of temperature information is much the same in flies and cockroaches. Axons of thermoreceptor neurons project to the margin of the antennal lobe and form glomeruli, from which cold, warm and cold-warm projection neurons originate, the last neurons being excited by both cooling and warming. Axons of antennal lobe thermosensory projection neurons of the antennal lobe terminate in three distinct areas of the protocerebrum, the mushroom body, lateral horn and posterior lateral protocerebrum, the last area also receiving termination of hygrosensory projection neurons. Such multiple thermosensory pathways may serve to control multiple forms of thermosensory behavior. Electrophysiological studies on cockroaches and transgenic approaches in flies are encouraged to complement each other for further elucidating general principles of thermosensory processing in the insect brain. [ABSTRACT FROM AUTHOR]

A new monotypic family, †Yantarocentridae (Insecta, Trichoptera), is described from Baltic amber. The type species,Yantarocentrus gusakovigen. et sp. nov., is a male showing good preservation of its head, palps, antennae and legs; the forewings are partially seen and the genitalia are faintly visible with translucent light. New characters of antenna have been introduced for the separation of this family from related taxa. The combination of characters shows the new family to be placed as a sister lineage of higher Plenitentoria, including Lepidostomatidae, Brachycentridae and Limnephiloidea. Some features, such as peculiar sensory fields on the antennae, are not found elsewhere in Trichoptera. http://zoobank.org/urn:lsid:zoobank.org:pub:69D4D9B3-0336-4666-8DFE-3C5173592AD2 [ABSTRACT FROM AUTHOR]

Animals are remarkably stable during high-speed maneuvers. As the speed of locomotion increases, neural bandwidth and processing delays can limit the ability to achieve and maintain stable control. Processing the information of sensory stimuli into a control signal within the sensor itself could enable rapid implementation of whole-body feedback control during high-speed locomotion. Here, we show that processing in antennal afferents is sufficient to act as the control signal for a fast sensorimotor loop. American cockroaches Periplaneta americana use their antennae to mediate escape running by tracking vertical surfaces such as walls. A control theoretic model of wall following predicts that stable control is possible if the animal can compute wall position (P) and velocity, its derivative (D). Previous whole-nerve recordings from the antenna during simulated turning experiments demonstrated a population response consistent with P and D encoding, and suggested that the response was synchronized with the timing of a turn executed while wall following. Here, we record extracellularly from individual mechanoreceptors distributed along the antenna and show that these receptors encode D and have distinct latencies and filtering properties. The summed output of these receptors can be used as a control signal for rapid steering maneuvers. The D encoding within the antenna in addition to the temporal filtering properties and P dependence of the population of afferents support a sensory-encoding notion from control theory. Our findings support the notion that peripheral sensory processing can enable rapid implementation of whole-body feedback control during rapid running maneuvers. [ABSTRACT FROM AUTHOR]

Chemotaxis is important for the survival of most animals. How the brain translates sensory input into motor output beyond higher olfactory processing centers is largely unknown. We describe a group of excitatory neurons, termed Odd neurons, which are important for Drosophila larval chemotaxis. Odd neurons receive synaptic input from projection neurons in the calyx of the mushroom body and project axons to the central brain. Functional imaging shows that some of the Odd neurons respond to odor. Larvae in which Odd neurons are silenced are less efficient at odor tracking than controls and sample the odor space more frequently. Larvae in which the excitability of Odd neurons is increased are better at odor intensity discrimination and odor tracking. Thus, the Odd neurons represent a distinct pathway that regulates the sensitivity of the olfactory system to odor concentrations, demonstrating that efficient chemotaxis depends on processing of odor strength downstream of higher olfactory centers. [ABSTRACT FROM AUTHOR]

Loss of the flight ability and wing reduction has been reported for many taxa of Coleoptera. If elytra are closed, their roots are clenched between the tergum and the pleuron, forces applied to the elytra can not be transmitted to the field of campaniform sensilla situated on the root. That is why it is plausible to assume that the field becomes redundant in non-flying beetles. We examined the relationships between the hind wing reduction and characters of this mechanosensory field in beetles of six families. We measured the size of the elytron, that of the hind wing and counted the number of sensilla in the sensory field. Mesopterous non-flying beetles retain one half to one third of sensilla present in macropterous species of the same body size. Further reduction of the sensory field in brachypterous species is obvious, but sensilla are still present in insects with strongly reduced wings, as long as their elytra are separable and mesothoracic axillaries are present. Complete loss of sensilla coincides with the existence of a permanent sutural lock. However, some beetles with permanently locked elytra and absence of axillaries still retain few campaniform sensilla. A very special case of an extreme wing modification in feather-wing beetles is considered. No sensilla were revealed either on the root of the elytron or on the basal segment of such fringed wings in flying ptiliid species. [ABSTRACT FROM AUTHOR]

Poikilothermic animals are affected by variations in environmental temperature, as the basic properties of nerve cells and muscles are altered. Nevertheless, insect sensory systems, such as the auditory system, need to function effectively over a wide range of temperatures, as sudden changes of up to 10 °C or more are common. We investigated the performance of auditory receptor neurons and properties of the tympanal membrane of Locusta migratoria in response to temperature changes. Intracellular recordings of receptors at two temperatures (21 and 28 °C) revealed a moderate increase in spike rate with a mean Q10 of 1.4. With rising temperature, the spike rate-intensity-functions exhibited small decreases in thresholds and expansions of the dynamic range, while spike durations decreased. Tympanal membrane displacement, investigated using microscanning laser vibrometry, exhibited a small temperature effect, with a Q10 of 1.2. These findings suggest that locusts are affected by shifts in temperature at the periphery of the auditory pathway, but the effects on spike rate, sensitivity, and tympanal membrane displacement are small. Robust encoding of acoustic signals by only slightly temperature-dependent receptor neurons and almost temperature-independent tympanal membrane properties might enable locusts and grasshoppers to reliably identify sounds in spite of changes of their body temperature. [ABSTRACT FROM AUTHOR]

The moist cell and the dry cell on the antenna of the male honeybee were exposed to humidities slowly rising and falling at rates between –1.5%/s and +1.5%/s and at varying amplitudes in the 10 to 90% humidity range. The two cells respond to these slow humidity oscillations with oscillations in impulse frequency which depend not only on instantaneous humidity but also on the rate with which humidity changes. The impulse frequency of each cell was plotted as a function of these two parameters and regression planes were fitted to the data points of single oscillation periods. The regression slopes, which estimate sensitivity, rose with the amplitude of humidity oscillations. During large-amplitude oscillations, moist and dry cell sensitivity for instantaneous humidity and its rate of change was high. During small-amplitude oscillations, their sensitivity for both parameters was low, less exactly reflecting humidity fluctuations. Nothing is known about the spatial and temporal humidity variations a honeybee may encounter when flying through natural environments. Microclimatic parameters (absolute humidity, temperature, wind speed) were measured from an automobile traveling through different landscapes of Lower Austria. Landscape type affected extremes and mean values of humidity. Differences between peaks and troughs of humidity fluctuations were generally smaller in open grassy fields or deciduous forests than in edge habitats or forest openings. Overall, fluctuation amplitudes were small. In this part of the stimulus range, hygroreceptor sensitivity is not optimal for encoding instantaneous humidity and the rate of humidity change. It seems that honeybee's hygroreceptors are specialized for detecting large-amplitude fluctuations that are relevant for a specific behavior, namely, maintaining a sufficiently stable state of water balance. The results suggest that optimal sensitivity of both hygroreceptors is shaped not only by humidity oscillation amplitudes but also according to their impact on behavior. [ABSTRACT FROM AUTHOR]

Summary: Multiple sensory cues emanating from humans are thought to guide blood-feeding female mosquitoes to a host. To determine the relative contribution of carbon dioxide (CO2) detection to mosquito host-seeking behavior, we mutated the AaegGr3 gene, a subunit of the heteromeric CO2 receptor in Aedes aegypti mosquitoes. Gr3 mutants lack electrophysiological and behavioral responses to CO2. These mutants also fail to show CO2-evoked responses to heat and lactic acid, a human-derived attractant, suggesting that CO2 can gate responses to other sensory stimuli. Whereas attraction of Gr3 mutants to live humans in a large semi-field environment was only slightly impaired, responses to an animal host were greatly reduced in a spatial-scale-dependent manner. Synergistic integration of heat and odor cues likely drive host-seeking behavior in the absence of CO2 detection. We reveal a networked series of interactions by which multimodal integration of CO2, human odor, and heat orchestrates mosquito attraction to humans. [ABSTRACT FROM AUTHOR]

Mosquitoes are a great threat to human health. Fortunately, they have a weakness: they utilize their sense of smell to target a human host. Recent studies examine the effectiveness of protecting humans from attack by ablating or odorant targeting mosquito olfactory receptors. The results are both promising and alarming. [ABSTRACT FROM AUTHOR]

Mating displays are often composed of multiple signals in multiple sensory modalities, with each individual signal contributing to the attractiveness of the displaying individual. Adult mate preferences for some of these signals are learned during premating, or juvenile, social experience with a sexually mature individual. While learned mate preferences have been described in multiple taxa, it is still unclear how the different display signals perceived during the learning period influence the development of adult mate preferences. Of particular interest is whether a learned mate preference for a sexual signal in one modality is context dependent (i.e. dependent on a second signal in either the same or a different sensory modality). Here we test whether a signal in one modality (odour) influences the interpretation (aversion or preference learning) of signals in a different modality (wing colour patterns) using the butterfly Bicyclus anynana. Previously we showed that female B. anynana learn to prefer additional ornaments, UV-reflective white spots, on the wings of males if they are exposed to these ornaments on the first day after eclosion from pupae. We now show that females exposed to males with manipulated odour do not learn to prefer these additional ornaments, and learn to avoid the wild-type male ornamentation. This aversion learning, where animals learn to avoid visual signals previously coupled with unattractive odours and to prefer visual signals previously coupled with attractive odours, demonstrates that visual mate preference learning in a butterfly is context dependent, and that specific sexual signals may have epistatic effects on mate preference development. [ABSTRACT FROM AUTHOR]

Highlights: [•] Individual auditory receptors of mosquito are tuned to different frequencies. [•] The frequency distribution of neurons is dominated by those tuned to frequencies between ∼75 and 125Hz. [•] We developed a novel positive feedback stimulation technique to test individual receptor tuning properties. [•] We suggest that mosquitoes have the potential to analyse sounds into individual frequency components. [Copyright &y& Elsevier]

Spotted wing drosophila, Drosophila suzukii, is a serious invasive pest impacting the production of multiple fruit crops, including soft and stone fruits such as strawberries, raspberries and cherries. Effective control is challenging and reliant on integrated pest management which includes the use of an ever decreasing number of approved insecticides. New means to reduce the impact of this pest that can be integrated into control strategies are urgently required. In many production regions, including the UK, soft fruit are typically grown inside tunnels clad with polyethylene based materials. These can be modified to filter specific wavebands of light. We investigated whether targeted spectral modifications to cladding materials that disrupt insect vision could reduce the incidence of D. suzukii. We present a novel approach that starts from a neuroscientific investigation of insect sensory systems and ends with infield testing of new cladding materials inspired by the biological data. We show D. suzukii are predominantly sensitive to wavelengths below 405 nm (ultraviolet) and above 565 nm (orange & red) and that targeted blocking of lower wavebands (up to 430 nm) using light restricting materials reduces pest populations up to 73% in field trials. [ABSTRACT FROM AUTHOR]

Sensory systems sample the external world actively, within the context of self-motion induced disturbances. Mammals sample olfactory cues within the context of respiratory cycles and have adapted to process olfactory information within the time frame of a single sniff cycle. In plume tracking insects, it remains unknown whether olfactory processing is adapted to wing beating, which causes similar physical effects as sniffing. To explore this we first characterized the physical properties of our odor delivery system using hotwire anemometry and photo ionization detection, which confirmed that odor stimuli were temporally structured. Electroantennograms confirmed that pulse trains were tracked physiologically. Next, we quantified odor detection in moths in a series of psychophysical experiments to determine whether pulsing odor affected acuity. Moths were first conditioned to respond to a target odorant using Pavlovian olfactory conditioning. At 24 and 48 h after conditioning, moths were tested with a dilution series of the conditioned odor. On separate days odor was presented either continuously or as 20 Hz pulse trains to simulate wing beating effects. We varied pulse train duty cycle, olfactometer outflow velocity, pulsing method, and odor. Results of these studies, established that detection was enhanced when odors were pulsed. Higher velocity and briefer pulses also enhanced detection. Post hoc analysis indicated enhanced detection was the result of a significantly lower behavioral response to blank stimuli when presented as pulse trains. Since blank responses are a measure of false positive responses, this suggests that the olfactory system makes fewer errors (i.e. is more reliable) when odors are experienced as pulse trains. We therefore postulate that the olfactory system of Manduca sexta may have evolved mechanisms to enhance odor detection during flight, where the effects of wing beating represent the norm. This system may even exploit temporal structure in a manner similar to sniffing. [ABSTRACT FROM AUTHOR]