The basic amines, 1-methylpiperazine and 1-methylpyrrolidine interfere with Aedes aegypti host-seeking behavior through a possible anosmic effect. This study investigated the effects of these compounds, along with triethylamine (an active ingredient in FlynapÔ anesthetic). Glass tube vapor phase assays of 1-methylpiperazine and 1-methylpyrrolidine on Ae. aegypti adult females showed initial repellency, followed by narcosis, knockdown, and paralysis. Under identical conditions, triethylamine showed quick knockdown without repellency, and the knockdown was reversible, unlike that of the other two amines. Electroantennographic (EAG) study showed significant responses of Ae. aegypti to the three basic amines; moreover, triethylamine increased the EAG response of background air (blank). I also studied the EAG responses of repellent/attractant standards (including VUAA-1, reported to be an Orco channel agonist) and a series of fluorinated phenylamide repellents. EAG responses of the pyrethroid-resistant Puerto Rico strain were significantly reduced for DEET, IR3535, and 2-undecanone, while no difference was observed for 1-octen-3-ol. These results corroborated our vapor phase repellency data for DEET, IR3535 and 2-undecanone, which showed significant cross resistance in the pyrethroid-resistant Puerto Rico strain. Among the experimental phenylamide repellents, only one showed a significantly greater EAG response than DEET. VUAA-1 gave no EAG response, but it significantly decreased the EAG response of the blank by 40%. Because a recent patent claimed thermal volatilization of VUAA-1 initiated an EAG response, we devised an induction coil heating system that induced vaporization of chemicals within seconds and without changing the overall air delivery temperature. Statistically significant increases in EAG responses were recorded for DEET and 1-octen-3-ol, at a temperature of 118 oC. These findings provide insights into the mode of action of basic amines and spatial repellents on mosquito behavior, and the induction heating system has the potential improve testing of rare and low volatility compounds with the EAG technique.

Vapor phase repellents: New methods, chemistry, and mechanisms of action

256th National Meeting (2018)

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