An inside look at the sensory biology of triatomines

Abstract

Although kissing bugs (Triatominae: Reduviidae) are perhaps best known as vectors of Chagas disease, they are important experimental models in studies of insect sensory physiology, pioneered by the seminal studies of Wigglesworth and Gillet more than eighty years ago. Since then, many investigations have revealed that the thermal, hygric, visual and olfactory senses play critical roles in the orientation of these blood-sucking insects towards hosts. Here we review the current knowledge about the role of these sensory systems, focussing on relevant stimuli, sensory structures, receptor physiology and the molecular players involved in the complex and cryptic behavioural repertoire of these nocturnal insects. Odours are particularly relevant, as they are involved in host search and are used for sexual, aggregation and alarm communication. Tastants are critical for a proper recognition of hosts, food and conspecifics. Heat and relative humidity mediate orientation towards hosts and are also important for the selection of resting places. Vision, which mediates negative phototaxis and flight dispersion, is also critical for modulating shelter use and mediating escape responses. The molecular bases underlying the detection of sensory stimuli started to be uncovered by means of functional genetics due to both the recent publication of the genome sequence of Rhodnius prolixus and the availability of modern genome editing techniques.

Molecular bases of sensory processes in kissing bugs, vectors of Chagas disease

“…Kissing bugs are nocturnal insects that search for hosts, including humans, exploiting multimodal sensory cues emitted by them [12]. Furthermore, other relevant sensory processes are those related to the detection of triatomine aggregation signals, sexual and alarm pheromones, stridulation signals mediating communication between sexes and microclimates (i.e., both relative humidity and temperature) of hiding places [12]. These features of bug biology represent opportunities for behavioral manipulation to promote their control.…”

“…To date, they have been better functionally characterized for D. melanogaster, having been related to the detection of food during foraging, the recognition of cuticular sexual signals and the sensing of CO2 [24]. Kissing bugs rely on taste sensing for the recognition of hosts and sexual partners and a total of 28 GRs have been described in the genome of R. prolixus [12,15,25]. Nevertheless, no bug GR has so far been functionally characterized.…”

“…Two GRs mediate the detection of CO2 in D. melanogaster [27], while three have been reported to be required for this task in mosquitoes [28]. Curiously, no orthologues have been found for these genes in the genome of R. prolixus [15], even though kissing bugs are well-known for their ability of exploiting this host cue during foraging [12]. Therefore, it is clear that a different mechanism should mediate this sensory competence in kissing bugs, as it is the case also for honeybees, ants and other insects lacking this GR lineage [29].…”

Transcriptomics supports local sensory regulation in the antenna of the kissing bugRhodnius prolixus

“…Rhodnius prolixus has been an important insect model for neuroethological studies for many decades 1,2 . Relevant aspects of its neuroethology, such as host odour-mediated behaviour 3,4 , circadian modulation 5 , the action of biogenic amines and neuropeptides 6 or the expression of behavioural plasticity 7,8 have been thoroughly studied.…”

“…Kissing-bug antennae are multimodal sensory organs dedicated to detect diverse stimuli associated to hosts 4 , microenvironmental features and intraspecific communication 2 . The physiological bases of sensory processes sit on receptor neurons that express specific membrane proteins that confer them an ability to react to specific stimuli present in the environment.…”