Vapor phase repellency and insecticidal activity of pyridinyl amides against Anopheline mosquitoes

Authors: CUBA, INGEBORG - University Of Florida; RICHOUX, GARY - University Of Florida; Norris, Edmund; BERNIER, ULRICH - Retired ARS Employee; Linthicum, Kenneth - Ken; BLOOMQUIST, JEFFREY - University Of Florida

Submitted to: Current Research in Parasitology and Vector Borne Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/11/2021
Publication Date: 11/18/2021
Citation: Cuba, I.H., Richoux, G.R., Norris, E.J., Bernier, U.R., Linthicum, K., Bloomquist, J.R. 2021. Vapor phase repellency and insecticidal activity of pyridinyl amides against Anopheline mosquitoes. Current Research in Parasitology and Vector Borne Diseases. 1:100062. https://doi.org/10.1016/j.crpvbd.2021.100062.
DOI: https://doi.org/10.1016/j.crpvbd.2021.100062

Interpretive Summary: Identifying new compounds is essential to control mosquito vector populations, and reduce the risk of mosquito transmitted diseases and acquiring resistance to commercially available active ingredients. DEET continues to be the gold standard topical repellent and Transfluthrin, a synthetic pyrethroid, is the gold standard spatial repellent. However, the effectiveness of DEET varies among mosquito species and tends to be less effective against Anopheles species mosquitoes. Additionally, the continuous usage of DEET can lead to resistance and reduced effectiveness and there is widespread resistance to synthetic pyrethroids like Transfluthirin. In this study we describe the testing of new chemicals for their ability to repel mosquitoes without contact, a phenomenon known as spatial repellency. We tested the spatial repellent activity and toxicity of two novel pyridinyl amides (1 and 2) chemical against 3 species of mosquitoes that can transmit malaria, Anopheles albimanus, Anopheles quadrimaculatus, and Anopheles gambiae. In spatial repellency evaluations in the laboratory, compound 2 was generally more effective than DEET, while compound 1 was about as active as these standards. Transfluthrin was the most active compound for inducing Anopheles mosquito repellency, knockdown, and lethality. Overall, this study provides insight for further synthesis of alternative amide compounds for use as spatial treatments.

Technical Abstract: It is important to identify safe repellents that can provide reliable protection from arthropod biting and prevent arthropod-borne diseases, such as malaria. In the present study, the spatial repellent activity and toxicity of two novel pyridinyl amides (1 and 2) were evaluated against Anopheles albimanus, Anopheles quadrimaculatus, and Anopheles gambiae. In vapor repellency bioassays, compound 2 was generally more effective than DEET and 2-undecanone, while compound 1 was about as active as these standards. Overall, transfluthrin was the most active compound for inducing anopheline mosquito repellency, knockdown, and lethality. Although they were not the most active repellents, the two experimental compounds s produced the largest electroantennographic responses in female antennae. Significant synergism was also observed for the mixture of a pyrethroid derived acid (TFA) and the repellent 2-undecanone compared to 2-undecanone by itself, similar to that observed previously in Aedes aegypti. Overall, this study provides insight for further synthesis of alternative amide compounds for use as spatial treatments.