Evolutionarily conserved odorant receptor function questions ecological context of octenol role in mosquitoes.

Amir Dekel,Esther Yakir,Ronald J Pitts,Jonathan D Bohbot

doi:10.1038/srep37330

Abstract

Olfaction is a key insect adaptation to a wide range of habitats. In the last thirty years, the detection of octenol by blood-feeding insects has been primarily understood in the context of animal host-seeking. The recent discovery of a conserved octenol receptor gene in the strictly nectar-feeding elephant mosquito Toxorhynchites amboinensis (TaOr8) suggests a different biological role. Here, we show that TaOR8 is a functional ortholog of its counterparts in blood-feeding mosquitoes displaying selectivity towards the (R)-enantiomer of octenol and susceptibility to the insect repellent DEET. These findings suggest that while the function of OR8 has been maintained throughout mosquito evolution, the context in which this receptor is operating has diverged in blood and nectar-feeding mosquitoes.

Highlights

IntroductionIn the last thirty years, the detection of octenol by blood-feeding insects has been primarily understood in the context of animal host-seeking
Olfaction is a key insect adaptation to a wide range of habitats
While amino-acid divergence is evenly distributed throughout the peptide sequence, highest amino-acid diversity is highest on the N-terminus of AaOR8, which exhibits an extra 26 amino-acids

Summary

Introduction

In the last thirty years, the detection of octenol by blood-feeding insects has been primarily understood in the context of animal host-seeking. The recent discovery of a conserved octenol receptor gene in the strictly nectar-feeding elephant mosquito Toxorhynchites amboinensis (TaOr8) suggests a different biological role. We show that TaOR8 is a functional ortholog of its counterparts in blood-feeding mosquitoes displaying selectivity towards the (R)-enantiomer of octenol and susceptibility to the insect repellent DEET. The recent discovery of the OR repertoire in the Elephant mosquitoes Toxorhynchites might be valuable to explore the role of octenol since animal host-seeking is not part of their behavior[23,24] (Fig. 1a). T. amboinensis and Ae. aegypti express www.nature.com/scientificreports/

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