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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Mosquito and Fly Research » Research » Publications at this Location » Publication #381653
Research Project: Integrated Pest Management of Mosquitoes and Biting Flies

Location: Mosquito and Fly Research

Title: Mode of action of nootkatone, a biorational insecticide and repellent

Author
item Norris, Edmund
item GELDENHUYS, WERNER - West Virginia University
item BLOOMQUIST, JEFFREY - University Of Florida

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/12/2021
Publication Date: 2/25/2021
Citation: Norris, E.J., Geldenhuys, W., Bloomquist, J.R. 2021. Mode of action of nootkatone, a biorational insecticide and repellent. Emerging Pathogens Institute Research Day. p.69-70.

Interpretive Summary:

Technical Abstract: Biorational vector control products are any chemistry that is inspired by or obtained from a natural plant compound, used for the purpose of controlling pest arthropods. As plants and insects have existed in a long evolutionary “arms race” with one-another, some of these compounds have potent bioactivities against various pest species. Moreover, we encounter these compounds every day in our food and perfumes. As such, they represent safer alternatives to synthetic insecticides and repellents, but they may be more labile in the environment. Nootkatone is a natural sesquiterpenoid found in grapefruit and one of the main constituents responsible for its characteristic aroma and flavor. It is an effective repellent and is toxic to mosquitoes and ticks, and its mode of action is not well understood. Experiments were therefore initiated to better understand the mode of action of nootkatone in a number of insect neurophysiological systems. Nootkatone was lethal to mosquitoes, synergized natural pyrethrins, and showed signs of neurotoxicity. It was inactive on a cockroach axonal preparation and showed a nerve blocking action on the larval Drosophila melanogaster central nervous system (CNS) preparation. It was successful in reversing the nerve blocking effect of applied GABA, an inhibitory neurotransmitter. Moreover, its GABA-blocking effect was reduced in a strain of D. melanogasterhaving a mutated GABA receptor (A302S) and this strain was resistant to the lethal effects of nootkatone. Molecular modeling studies indicated that the mutation could account for reduced nootkatone binding within the chloride ion channel of the GABA receptor. These studies demonstrate that the lethal effects of nootkatone are mediated via GABAergic pathways in insects, but are unlikely to explain its repellent effects. The implications of these results for the commercialization of nootkatone for vector control are discussed.