Molecular and functional characterization of a conserved odorant receptor from Aedes albopictus

Abstract

Background The Asian tiger mosquito Aedes albopictus is a competent vector of several viral arboviruses including yellow fever, dengue fever, and chikungunya. Several vital mosquito behaviors (e.g., feeding, host-seeking, mating, and oviposition) are primarily dependent on the olfactory system for semiochemicals detection and discrimination. However, the limited number of studies hampers our understanding of the relationships between the Ae. albopictus olfactory system and the complex chemical world. Methods We performed RT-qPCR assay on antennae of Ae. albopictus mosquitoes of different sexes, ages and physiological states, and found odorant receptor 11 (AalbOr11) enriched in non-blood-fed female mosquitoes. Then, we examined the odorant preference with a panel of physiologically and behaviorally relevant odorants in Xenopus oocytes. Results The results indicated that AalbOr11 could be activated by ten aromatics, seven terpenes, six heterocyclics, and three alcohols. Furthermore, using post-RNA interference (RNAi) hand-in-cage assay, we found that reducing the transcript level of AalbOr11 affected the repellency activity mediated by (+)-fenchone at a lower concentration (0.01% v/v). Conclusions Using in vitro functional characterization, we found that AalbOr11 was a broadly tuned receptor. Moreover, we found that AalbOr11 shared a conserved odorant reception profile with homologous Anopheles gambiae Or11. In addition, RNAi and bioassay suggested that AablOr11 might be one of the receptors mediating (+)-fenchone repellency activity. Our study attempted to link odor-induced behaviors to odorant reception and may lay the foundation for identifying active semiochemicals for monitoring or controlling mosquito populations. Graphical Abstract

A highly expressed odorant receptor from the yellow fever mosquito, AaegOR11, responds to (+)- and (-)-fenchone and a phenolic repellent

“…Given the discrepancy between the literature [17, 18] and our findings, we tested whether the (+)- and (-)-fenchone repel Cx. quinquefasciatus , but neither isomer showed repellency activity.…”

“…aegypti [17] and Ae. albopictus [18] comparable to DEET, but a moderate repellent 30 min after sample preparation and about 50% activity one hour later [17]. We tested both (+)-fenchone and (-)-fenchone with our surface-landing and feeding assay [9, 19, 20], and using freshly prepared samples.…”

The updated genome of the Hungarian population of Aedes koreicus

“…koreicus , but also provides potential targets for the control of this vector species. These targets should be investigated with a larger sample size to validate their structure and function and potentially suggest specific repellent molecules (see: Yan et al (2022) 36 and Tiwari and Sowdhamini (2023) 37 ). Out of 27 potential insecticide resistance genes 35 , 38 , we were able to identify the homolog of aael 012918, ace 1, cyp 6bb2, ABCA 3, cuticle protein, cuticle protein CP14.6, cyp 9j26, cyp 9j28, cyp 9j32, ketohexokinase, modifier of mdg 4, muscle calcium channel subunit alpha-1, nav , potassium voltage-gated channel protein Shaker, rdl , sodium leak channel non-selective protein and uncharacterized LOC5575776 (Supplementary Table 2).…”

The Odorant Receptor Recognizing Camphor in a Camphor Tree Specialist Orthaga achatina (Lepidoptera: Pyralidae)

“…In addition, OR16 also had a remarkable response to eucalyptol, a volatile of high structural similarity with camphor, which is also used as a component of some pest repellents due to its antiinflammatory and antibacterial effects. 33−35 ORs tuning to camphor have been reported in several other insects such as Aedes albopictus, 36 Culex quinquefasciatus, 37 Ips typographus, 38 and H. armigera, 39 but camphor is not the major ligand and induced only weak response to these ORs. In addition, sequences among these ORs and O. achatina OR16 share a very low level of amino acid identity (Figure S3).…”