Evolution, developmental expression and function of odorant receptors in insects

Abstract

Animals rely on their chemosensory system to discriminate among a very large number of attractive or repulsive chemical cues in the environment, which is essential to respond with proper action. The olfactory sensory systems in insects share significant similarities with those of vertebrates, although they also exhibit dramatic differences, such as the molecular nature of the odorant receptors (ORs): insect ORs function as heteromeric ion channels with a common Orco subunit, unlike the G-protein-coupled olfactory receptors found in vertebrates. Remarkable progress has recently been made in understanding the evolution, development and function of insect odorant receptor neurons (ORNs). These studies have uncovered the diversity of olfactory sensory systems among insect species, including in eusocial insects that rely extensively on olfactory sensing of pheromones for social communication. However, further studies, notably functional analyses, are needed to improve our understanding of the origins of the Orco–OR system, the mechanisms of ORN fate determination, and the extraordinary diversity of behavioral responses to chemical cues.

Insect repellents mediate species-specific olfactory behaviours in mosquitoes

“…Anophelinae and Culicinae diverged between 145 and 200 million years ago [16,17] (Fig. 1a), which is sufficient time for insect olfactory systems to evolve independently and respond differently to odorants, including repellents [18][19][20][21][22][23][24][25]. Therefore, the lack of agreement on how DEET and other mosquito repellents work from previous studies might reflect the assumption and use of a single mosquito species as representative for all mosquito species [4,[6][7][8][9][10][11]13].…”

Targeted molecular profiling of rare cell populations identifies olfactory sensory neuron fate and wiring determinants

“…While OSN fate is established in early pupae [1][2][3] , the expression of Pdm3 in Ir75a neurons in adult antennae ( Figure 5A-B) suggests that it has a persistent role in these cells. To test this idea, we drove pdm3 RNAi using Ir8a-Gal4 , which is active only from the second half of pupal development (∼48 h APF) by which time OSN axonal convergence on glomeruli has occurred.…”

Insect Repellents Mediate Species-Specific Olfactory Behaviours in Mosquitoes

“…Anophelinae and Culicinae diverged between 145 and 200 million years ago [16,17] (Fig.1a), which is sufficient time for insect olfactory systems to evolve independently and respond differently to odorants, including repellents [18][19][20][21][22][23][24][25]. Therefore, the lack of agreement on how DEET and other mosquito repellents work from previous studies might reflect the assumption and use of a single mosquito species as representative for all mosquito species [4,[6][7][8][9][10][11]13].…”