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

Abstract

SUMMARY 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. Here we examine larval olfactory responses, in which the peripheral components are associated with the antennal sensory cone. Larval behavior and sensory cone responses to volatile stimuli in Anopheles coluzzii demonstrate the sensory cone is particularly tuned to alcohols, thiazoles, and heterocyclics, and these responses can be assigned to discrete groups of sensory cone neurons with distinctive profiles. These studies reveal that the anopheline larvae actively sample volatile odors above their aquatic habitats via a highly sophisticated olfactory system that is sensitive to a broad range of compounds with significant behavioral relevance.

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

“…AcIr76b expression was also examined across the larval antennae of An. coluzzii , which is the principal sensory appendage of this aquatic preadult life stage ( 41 , 52 ). In addition to robust labeling of larval antennal neuronal cell bodies, which are clustered within the antennal shaft ( SI Appendix , Fig.…”

“…SSRs were carried out as previously described ( 40 , 41 ) with minor modifications. Female adult mosquitoes (4 to 10 d after eclosion) were mounted on a microscope slide (76 × 26 mm).…”

Imaging and spectral analysis of autofluorescence patterns in larval head structures of mosquito vectors

“…Mosquito larvae are aquatic and employ a wide range of physiological sensory systems to navigate in their habitats to find food and avoid predators. 38 As a feature common to other dipteran species, mosquito larvae have a set of anterior appendages, including the antennae that apically carry a sensory cone considered to have olfactory functions and peg organs with putative gustatory roles. 39-42 The molecular and physiological machinery underlying olfaction in mosquito larvae, accounted by the expression of olfactory, ionotropic and gustatory receptors, is increasingly being elucidated.…”

“… 39-42 The molecular and physiological machinery underlying olfaction in mosquito larvae, accounted by the expression of olfactory, ionotropic and gustatory receptors, is increasingly being elucidated. 38 , 41 , 43-48 …”

“…pipiens , with particular attention to mouth brushes and antennae, for their already recognized roles as mediators of behavioral functions. 38 , 5 Albeit limited to Ae. albopictus and Cx.…”