An official website of the United States government
Mosquitoes can change their feeding behaviours based on past experiences, such as shifting from biting animals to biting humans or avoiding defensive hosts (Wolff & Riffell 2018J. Exp. Biol.221, jeb157131. (doi:10.1242/jeb.157131)). Dopamine is a critical neuromodulator for insects, allowing flexibility in their feeding preferences, but its role in the primary olfactory centre, the antennal lobe (AL), remains unclear (Vinaugeret al.2018Curr. Biol.28, 333–344.e8. (doi:10.1016/j.cub.2017.12.015)). It is also unknown whether mosquitoes can learn some odours and not others, or whether different species learn the same odour cues. We assayed aversive olfactory learning in four mosquito species with different host preferences, and found that they differentially learn odours salient to their preferred host. Mosquitoes that prefer humans learned odours found in mammalian skin, but not a flower odour, and a nectar-feeding species only learned a floral odour. Comparing the brains of these four species revealed significantly different innervation patterns in the AL by dopaminergic neurons. Calcium imaging in theAedes aegyptiAL and three-dimensional image analyses of dopaminergic innervation show that glomeruli tuned to learnable odours have significantly higher dopaminergic innervation. Changes in dopamine expression in the insect AL may be an evolutionary mechanism to adapt olfactory learning circuitry without changing brain structure and confer to mosquitoes an ability to adapt to new hosts.
more »
« less
The olfactory neurobiology and chemical ecology of mosquito attraction to plant nutrient sources
Invasive mosquito species are key vectors of arboviral diseases, like dengue, zika and chikungunya, posing significant public health challenges worldwide. These issues are worsened by urbanization, climate change and insecticide resistance, driving research into new control methods. Adult mosquitoes are attracted to plant nutrient sources essential for flight and reproduction. However, few studies have examined the odours emitted by these sources, and little is known about the olfactory neurobiology of mosquito–plant interactions. This review synthesizes current knowledge on the broad classes of volatile compounds that modulate mosquito behaviour, focusing on the olfactory processes underlying mosquito responses to plant nutrient sources. We also discuss the application of neurogenetic tools for investigating the role of olfactory receptor genes and neural circuits in mosquito ecology. Finally, we explore how insights from these studies can inform and enhance mosquito control strategies, including developing synthetic lures for attractive toxic sugar baits and improved trapping and surveillance technologies. Defining the olfactory receptors, sensory neurons and neural circuits mediating attraction or repellency to plant odours is crucial for optimizing mosquito monitoring and control interventions.
more »
« less
- Award ID(s):
- 2124777
- PAR ID:
- 10665642
- Publisher / Repository:
- Royal Society
- Date Published:
- Journal Name:
- Proceedings of the Royal Society B: Biological Sciences
- Volume:
- 292
- Issue:
- 2057
- ISSN:
- 1471-2954
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Sensory input across modalities is highly dynamic, continuously confronting the brain with the task of making sense of the external world. Olfaction is a key sense that many species depend on for survival, for example to locate food sources and mating partners or to avoid encountering predators. In the absence of visual cues, olfactory cues are especially useful, as they provide information over a large range of distances. Natural odours form temporally complex plumes that show rapid fluctuations in odour concentration carrying information about the location of an odour source. This review focuses on how primarily mammals use this spatial information from olfactory cues to navigate their environment. I highlight progress made on the physical description of dynamically fluctuating odours, behavioural paradigms to investigate odour-guided navigation and review initial findings on the underlying neural mechanisms that allow mammals to extract spatial information from the dynamic odour landscape.more » « less
-
null (Ed.)Changes in behaviour often drive rapid adaptive evolution and speciation. However, the mechanistic basis for behavioural shifts is largely unknown. The tephritid fruit fly Rhagoletis pomonella is an example of ecological specialization and speciation in action via a recent host plant shift from hawthorn to apple. These flies primarily use specific odours to locate fruit, and because they mate only on or near host fruit, changes in odour preference for apples versus hawthorns translate directly to prezygotic reproductive isolation, initiating speciation. Using a variety of techniques, we found a reversal between apple and hawthorn flies in the sensory processing of key odours associated with host fruit preference at the first olfactory synapse, linking changes in the antennal lobe of the brain with ongoing ecological divergence. Indeed, changes to specific neural pathways of any sensory modality may be a broad mechanism for changes in animal behaviour, catalysing the genesis of new biodiversity.more » « less
-
ABSTRACT Feeding on the nutrients from fruits and flowers is vital for mosquitoes and increases their lifespan, reproduction and flight activity. Olfaction is a key sensory modality in mediating mosquito responses to nutrient sources. Previous studies have demonstrated that fruits and flowers can vary in attractiveness to mosquitoes, with some sources preferred over others. However, how the attractiveness of different fruits relates to the chemical composition of their odor and the responses they evoke from the mosquito's peripheral olfactory system is still not understood. In this study, we used closely related fruit species and their cultivars to examine how changes in odor chemistry can influence the fruit's attractiveness to Aedes aegypti mosquitoes. Our results show that mosquitoes are attracted to the odors of certain fruits (Mangifera indica, Prunus persica and Musa acuminata), whereas others (Pyrus communis and Citrus limon) were not attractive. Chemical analyses of the odors showed that attractive fruits have distinct chemical profiles, and amongst closely related fruits, minor changes in the relative proportions of odor compounds can modify their attractiveness. By contrast, electroantennogram responses showed similar responses across different fruits. Selectively altering the chemical proportion of a single compound in an odor was sufficient to either increase or decrease its attractiveness to levels similar to those of its closely related congener. Our results demonstrate that mosquitoes are sensitive to the proportions of compounds in attractive odors, which have implications for the olfactory processing of complex odor sources, such as those from plants or blood hosts.more » « less
-
Abstract Using odors to find food and mates is one of the most ancient and highly conserved behaviors. Arthropods from flies to moths to crabs use broadly similar strategies to navigate toward odor sources—such as integrating flow information with odor information, comparing odor concentration across sensors, and integrating odor information over time. Because arthropods share many homologous brain structures—antennal lobes for processing olfactory information, mechanosensors for processing flow, mushroom bodies (or hemi-ellipsoid bodies) for associative learning, and central complexes for navigation, it is likely that these closely related behaviors are mediated by conserved neural circuits. However, differences in the types of odors they seek, the physics of odor dispersal, and the physics of locomotion in water, air, and on substrates mean that these circuits must have adapted to generate a wide diversity of odor-seeking behaviors. In this review, we discuss common strategies and specializations observed in olfactory navigation behavior across arthropods, and review our current knowledge about the neural circuits subserving this behavior. We propose that a comparative study of arthropod nervous systems may provide insight into how a set of basic circuit structures has diversified to generate behavior adapted to different environments.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1098/rspb.2025.1806
