Binary mixtures of Vanderbilt University allosteric agonist thermolysis components act as volatile spatial repellents for malaria vector mosquitoes.

Background: The development of economically viable and environmentally neutral tools to control insects that consume or damage over 20% of global agriculture or vector human and animal disease represents one of the most important challenges of the 21st century. The suite of chemical-based strategies currently employed to control insect populations rely primarily on insecticides, which are subject to rapid resistance and often have harmful off-target environmental and health-related impacts, and, to a lesser degree, repellents, which typically rely on masking attractive odors. The discovery and characterization of Vanderbilt University allosteric agonists (VUAAs), a family of small-molecule agonists that target the highly conserved, insect-specific odorant receptor coreceptor (Orco), raise the potential for the development of a novel repellent paradigm for vector/pest management.

Age and Task Modulate Olfactory Sensitivity in the Florida Carpenter Ant .

Age-related changes in behavior and sensory perception have been observed in a wide variety of animal species. In ants and other eusocial insects, workers often progress through an ordered sequence of olfactory-driven behavioral tasks. Notably, these behaviors are plastic, and workers adapt and rapidly switch tasks in response to changing environmental conditions.

Age and Task Modulate Olfactory Sensitivity in the Florida Carpenter Ant .

Unlabelled: Age-related changes in behavior and sensory perception have been observed in a wide variety of animal species. In ants and other eusocial insects, workers often progress through an ordered sequence of olfactory-driven behavioral tasks. Notably, these behaviors are plastic, and workers adapt and rapidly switch tasks in response to changing environmental conditions.

Olfactory sensitivity differentiates morphologically distinct worker castes in Camponotus floridanus.

Background: Camponotus floridanus ant colonies are comprised of a single reproductive queen and thousands of sterile female offspring that consist of two morphologically distinct castes: smaller minors and larger majors. Minors perform most of the tasks within the colony, including brood care and food collection, whereas majors have fewer clear roles and have been hypothesized to act as a specialized solider caste associated with colony defense. The allocation of workers to these different tasks depends, in part, on the detection and processing of local information including pheromones and other chemical blends such as cuticular hydrocarbons.

Examining Peripheral Electrophysiological Responses of the Larval Antennal Sensory Cone of to Volatile Odorants.

Anopheline larvae rely on their antennae to respond to a complex suite of stimuli with which they navigate their aquatic environment, search for food, and avoid predators and pollution. Chemosensory signaling initiates on dendrites innervating the sensory peg and sensory cone, which are adjacently located at the distal (apical) end of the larval antennae. These structures are the primary sites for the detection of both soluble and volatile semiochemicals, which are biologically relevant chemical signals (typically unitary or blends of compounds) released by one organism that affect the behavior of another.

Physiological and Behavioral Characterization of Larval Olfaction in the Malaria Vector Mosquito .

When viewed from both academic and vector-control perspectives, the chemosensory biology of larval-stage anopheline mosquitoes is both enigmatic and paradoxical. As is true for all mosquito species, anopheline larvae are free-swimming organisms that use complex sensory processes to both locate nutrients and avoid predators. Because of their obligatory and therefore restrictive aquatic habitats, mosquito larvae are the most easily sampled and targeted mosquito life stage and as such they have been the focus of the majority of vector control strategies used to date.

Cup and Pan Behavioral Assays for Assessing Larval Volatile Responses.

Larval stage are highly reliant on their olfactory system to locate food sources and to avoid predators and less advantageous microenvironments within their aqueous habitats. The major larval chemosensory appendage, the antenna, is a complex organ with multiple sensory components that is responsible for both gustation and olfaction, thereby facilitating the detection and of both soluble and volatile compounds of biological relevance. Such compounds include food sources, predators, and a range of environmental toxicants.

Discrete roles of Ir76b ionotropic coreceptor impact olfaction, blood feeding, and mating in the malaria vector mosquito .

Anopheline mosquitoes rely on their highly sensitive chemosensory apparatus to detect diverse chemical stimuli that drive the host-seeking and blood-feeding behaviors required to vector pathogens for malaria and other diseases. This process incorporates a variety of chemosensory receptors and transduction pathways. We used advanced in vivo gene-editing and -labeling approaches to localize and functionally characterize the ionotropic coreceptor AcIr76b in the malaria mosquito Anopheles coluzzii, where it impacts both olfactory and gustatory systems.

Pleiotropic Odorant-Binding Proteins Promote Aedes aegypti Reproduction and Flavivirus Transmission.

Insect odorant-binding proteins (OBPs) are small soluble proteins that have been assigned roles in olfaction, but their other potential functions have not been extensively explored. Using CRISPR/Cas9-mediated disruption of Aedes aegypti and , we demonstrate the pleiotropic contribution of these proteins to multiple processes that are essential for vectorial capacity. Mutant mosquitoes have impaired host-seeking and oviposition behavior, reproduction, and arbovirus transmission.

Neuronal odor coding in the larval sensory cone of Anopheles coluzzii: Complex responses from a simple system.

Anopheles mosquitoes are the sole vectors of malaria. Although adult females are directly responsible for disease transmission and accordingly have been extensively studied, the survival of pre-adult larval stages is vital. Mosquito larvae utilize a spectrum of chemosensory and other cues to navigate their aquatic habitats to avoid predators and search for food.

Ammonium transporter AcAmt mutagenesis uncovers reproductive and physiological defects without impacting olfactory responses to ammonia in the malaria vector mosquito Anopheles coluzzii.

Anopheline mosquitoes are the sole vectors of malaria and rely on olfactory cues for host seeking in which ammonia derived from human sweat plays an essential role. To investigate the function of the Anopheles coluzzii ammonium transporter (AcAmt) in the mosquito olfactory system, we generated an AcAmt null mutant line using CRISPR/Cas9. AcAmt mutants displayed a series of novel phenotypes compared with wild-type mosquitoes including significantly lower insemination rates during mating and increased mortality during eclosion.

Advances in the Study of Olfaction in Eusocial Ants.

Over the past decade, spurred in part by the sequencing of the first ant genomes, there have been major advances in the field of olfactory myrmecology. With the discovery of a significant expansion of the odorant receptor gene family, considerable efforts have been directed toward understanding the olfactory basis of complex social behaviors in ant colonies. Here, we review recent pivotal studies that have begun to reveal insights into the development of the olfactory system as well as how olfactory stimuli are peripherally and centrally encoded.

Mutagenesis of the orco odorant receptor co-receptor impairs olfactory function in the malaria vector Anopheles coluzzii.

Mosquitoes rely heavily on their olfactory systems for host seeking, selection of oviposition sites, and avoiding predators and other environmental dangers. Of these behaviors, the preferential selection of a human blood-meal host drives the vectorial capacity of anthropophilic female Anopheles coluzzii mosquitoes. Olfactory receptor neurons (ORNs) are dispersed across several appendages on the head and express an obligate odorant receptor co-receptor (Orco) coupled with a "tuning" odorant receptor (OR) to form heteromeric, odor-gated ion channels in the membrane of these neurons.

Gene editing reveals obligate and modulatory components of the CO receptor complex in the malaria vector mosquito, Anopheles coluzzii.

The sensitivity to volatile carbon dioxide (CO) produced by humans and other animals is a critical component in the host preference behaviors of the malaria vector mosquito Anopheles coluzzii. The molecular receptors responsible for the ability to sense CO are encoded by three putative gustatory receptor (Gr) genes (Gr22,23,24) which are expressed in a distinctive array of sensory neurons housed in maxillary palp capitate peg sensilla of An. coluzzii.

Heterogeneous expression of the ammonium transporter AgAmt in chemosensory appendages of the malaria vector, Anopheles gambiae.

Ammonia is one of the principal kairomones originating from human and other animal emanations and in that context, plays an essential role in the host-seeking behaviors of the malaria vector mosquito Anopheles gambiae. Nevertheless, despite its importance in directing host-seeking, the mechanisms underlying ammonia detection in the mosquito olfactory system remains largely unknown. In addition to ongoing efforts to identify and characterize the molecular receptors that underlie ammonia sensitivity, previous studies have revealed a prominent role for ammonium transporters (Amt) in modulating antennal and behavioral responses in Drosophila melanogaster and An.

Odor coding of nestmate recognition in the eusocial ant .

In eusocial ants, aggressive behaviors require the ability to discriminate between chemical signatures such as cuticular hydrocarbons that distinguish nestmate friends from non-nestmate foes. It has been suggested that a mismatch between a chemical signature (label) and the internal, neuronal representation of the colony odor (template) leads to aggression between non-nestmates. Moreover, a definitive demonstration that odorant receptors are responsible for the processing of the chemical signals that regulate nestmate recognition has thus far been lacking.

Olfactory receptor gene abundance in invasive breast carcinoma.

Expression of olfactory receptors (ORs) has been reported in many human tissues outside the nasal epithelium. ORs have been validated as biomarkers in prostate cancer. In breast cancer, however, the expression and role of OR genes remain understudied.

Antennal Olfactory Physiology and Behavior of Males of the Ponerine Ant Harpegnathos saltator.

In comparison to the large amount of study on the communication abilities of females in ant societies and their associated chemical ecology and sensory physiology, such study of male ants has been largely ignored; accordingly, little is known about their olfactory sensory capabilities. To address this, we explored peripheral odor sensitivities in male Harpegnathos saltator by measuring the electrophysiological activity of olfactory sensory neurons within antennal trichoid and coeloconic sensilla using an extracellular recording technique. In an initial trial of 46 compounds, sensilla trichodea responded strongly to two alarm pheromone components, while a limited number of non-hydrocarbon odorants elicited strong responses in sensilla coeloconica.

Characterization of Chemosensory Responses on the Labellum of the Malaria Vector Mosquito, Anopheles coluzzii.

Anopheles gambiae coluzzii (An. coluzzii) uses olfaction to modulate a range of critical behaviors that are essential for survival and reproduction; most notably, host preference and selection underlie its vectorial capacity for human malaria. As is the case for all mosquitoes, An.

Deciphering the olfactory repertoire of the tiger mosquito Aedes albopictus.

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.

Profiles of soluble proteins in chemosensory organs of three members of the afro-tropical Anopheles gambiae complex.

In female mosquitoes, host-seeking and preference as well as several other important behaviors are largely driven by olfaction. Species of the Afrotropical Anopheles gambiae complex display divergent host-preference that are associated with significant differences in their vectorial capacity for human malaria. Olfactory sensitivity begins with signal transduction and activation of peripheral sensory neurons that populate the antennae, maxillary palps and other appendages.

Specialized odorant receptors in social insects that detect cuticular hydrocarbon cues and candidate pheromones.

Eusocial insects use cuticular hydrocarbons as components of pheromones that mediate social behaviours, such as caste and nestmate recognition, and regulation of reproduction. In ants such as Harpegnathos saltator, the queen produces a pheromone which suppresses the development of workers' ovaries and if she is removed, workers can transition to a reproductive state known as gamergate. Here we functionally characterize a subfamily of odorant receptors (Ors) with a nine-exon gene structure that have undergone a massive expansion in ants and other eusocial insects.

An Engineered orco Mutation Produces Aberrant Social Behavior and Defective Neural Development in Ants.

Ants exhibit cooperative behaviors and advanced forms of sociality that depend on pheromone-mediated communication. Odorant receptor neurons (ORNs) express specific odorant receptors (ORs) encoded by a dramatically expanded gene family in ants. In most eusocial insects, only the queen can transmit genetic information, restricting genetic studies.

Functional characterization of odorant receptors in the ponerine ant, .

Animals use a variety of sensory modalities-including visual, acoustic, and chemical-to sense their environment and interact with both conspecifics and other species. Such communication is especially critical in eusocial insects such as honey bees and ants, where cooperation is critical for survival and reproductive success. Various classes of chemoreceptors have been hypothesized to play essential roles in the origin and evolution of eusociality in ants, through their functional roles in pheromone detection that characterizes reproductive status and colony membership.