Avoidance of the Plant Hormone Cis-Jasmone by Aedes aegypti Depends On Mosquito Age in Both Plant and Human Odor Backgrounds

Jetske G De Boer,Joeri Groot,Joop J A Van Loon,Aron P S Kuiper

doi:10.1007/s10886-021-01299-2

Jetske G De Boer, Joeri Groot + Show 2 more

Open Access

https://doi.org/10.1007/s10886-021-01299-2

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Abstract

Adults of many mosquito species feed on plants to obtain metabolic energy and to enhance reproduction. Mosquitoes primarily rely on olfaction to locate plants and are known to respond to a range of plant volatiles. We studied the olfactory response of the yellow fever mosquito Aedes aegypti to methyl jasmonate (MeJA) and cis-jasmone (CiJA), volatile compounds originating from the octadecanoid signaling pathway that plays a key role in plant defense against herbivores. Specifically, we investigated how Ae. aegypti of different ages responded to elevated levels of CiJA in two attractive odor contexts, either derived from Lima bean plants or human skin. Aedes aegypti females landed significantly less often on a surface with CiJA and MeJA compared to the solvent control, CiJA exerting a stronger reduction in landing than MeJA. Odor context (plant or human) had no significant main effect on the olfactory responses of Ae. aegypti females to CiJA. Mosquito age significantly affected the olfactory response, older females (7–9 d) responding more strongly to elevated levels of CiJA than young females (1–3 d) in either odor context. Our results show that avoidance of CiJA by Ae. aegypti is independent of odor background, suggesting that jasmonates are inherently aversive cues to these mosquitoes. We propose that avoidance of plants with elevated levels of jasmonates is adaptive to mosquitoes to reduce the risk of encountering predators that is higher on these plants, i.e. by avoiding ‘enemy-dense-space’.

Highlights

Adults of many mosquito species feed on plant fluids to obtain metabolic energy and to enhance reproduction, and plants provide the only source of energy for male mosquitoes (Barredo and DeGennaro 2020; Foster 1995; Peach and Gries 2020)
The landing assay showed that Ae. aegypti females landed significantly less often on a surface with CiJA and methyl jasmonate (MeJA) compared to EtOH (Table 1)
On average less than one landing per mosquito was observed on 1% CiJA, while approximately 2 landings per mosquito were recorded on 1% MeJA (P < 0.001)

Summary

Introduction

Adults of many mosquito species feed on plant fluids to obtain metabolic energy and to enhance reproduction, and plants provide the only source of energy for male mosquitoes (Barredo and DeGennaro 2020; Foster 1995; Peach and Gries 2020). Plants continue to be exploited in the search for natural and safe mosquito repellents to replace synthetic compounds such as DEET (N,N-diethyl3-methylbenzamide) that remains the most widely used insect repellent to date (Chellappandian et al 2018; Grison et al 2020). In this respect, Xu et al (2014) made an interesting discovery when they demonstrated that the plant compound methyl jasmonate (MeJA) activates the same odorant receptor as DEET in the southern house mosquito Culex quinquefasciatus. C. quinquefasciatus is repelled by MeJA as well as by the closely related compound methyl dihydrojasmonate (Xu et al 2014; Zeng et al 2018), and the tick Ixodes ricinus is repelled by MeJA (Garboui et al 2007)

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