Citronellal perception and transmission by Anopheles gambiae s.s. (Diptera: Culicidae) females

Abstract

Anopheles gambiae s.s. is a key vector of Plasmodium parasites. Repellents, which may be a promising alternative to pesticides used to control malaria mosquitoes. Although citronellal is a known mosquito repellent, its repellency characteristics are largely unknown. Determining the specific odorant-binding proteins (OBPs) and odorant receptors (ORs) that detect and transfer the citronellal molecule in A. gambiae s.s. will help to define the mode of action of this compound. In this research, we assessed the repellent activity of citronellal in A. gambiae s.s. using a Y-tube olfactory meter, screened candidate citronellal-binding OBPs and ORs using reverse molecular docking, clarified the binding properties of predicted proteins for citronellal using fluorescence competition binding assay. Results showed that citronellal had a dosage effect on repelling A. gambiae s.s.. The 50% repellent rate was determined to be 4.02 nmol. Results of simulated molecular docking showed that the only proteins that bound tightly with citronellal were AgamOBP4 and AgamORC7. Fluorescence competitive binding assays confirmed the simulations. This research determined that citronellal was captured by AgamOBP4 and transmitted to AgamORC7 in A. gambiae s.s.. Our study will be beneficial in the further understanding the repellent mechanism of citronellal against A. gambiae s.s..

Natural Product Citronellal can Significantly Disturb Chitin Synthesis and Cell Wall Integrity in Magnaporthe oryzae

“…It is naturally present in citronella oil and eucalyptus oil, which is widely used in medicine, edible spices, and agriculture [18]. For example, citronellal can inhibit the expression of leukotrienes, reduce inflammation, reduce edema, anti-inflammatory and analgesic [19,20], and it is an effective mosquito repellent [21]. It can also be used to add flavor to food and beverages and enrich the aroma of products, such as synthetic menthone, menthol, citronellol, hydroxycitronellal, and other edible incense materials [22].…”

Pesticidal Activity and Mode of Action of Monoterpenes

“…In laboratory screening bioassays, citronellal and essential oils containing citronellal exhibit fumigant and herbicidal activities. Citronellal can function as a fumigant against the mosquito (Anopheles gambiae) and whitefly (Bemisia tabaci) and has an LC 50 value of 2.2 mg/L against the males and females of the fruit fly (Drosophila suzukii) . EOs of Cymbopogon zeylanicym, Cymbopogon winterianus, and Eucalyptus citriodora containing citronellal are herbicidal against Arabidopsis thaliana and Phalaris minor .…”

“…The repellent activity of monoterpenes may be related to their influence on the olfactory and gustatory receptor systems of insects . For example, citronellal binds to odorant-binding protein AgamOBP4 and odorant receptor AgamORC7 . Eugenol inhibits the activities of TRP channels that play a key signal transduction role in an insect sensory system .…”

Biological activity of cinnamaldehyde, citronellal, geraniol and anacardic acid on Haemonchus contortus isolates susceptible and resistant to synthetic anthelmintics

“…Citronellal is the major component of the essential oil of Eucalyptus citriodora . It has proven effectiveness as an antimicrobial ( Bezerra et al, 2019 ), repellent action against Anopheles gambiae s.s. ( Wu et al, 2020 ), action against Staphylococcus aureus and Escherichia coli biofilms ( Borges et al, 2017 ) and action against nematode eggs and larvae ( Araújo-Filho et al, 2018 ).…”