Effects of trifluoromethyl ketones and related compounds on the EAG and behavioural responses to pheromones in male moths

Trifluoromethyl ketones (TFMKs) and analogues affect pheromone detection and behaviour in male moths. 3-Octylthio-1,1,1-trifluoropropan-2-one (OTFP), one of the most effective antiesterase agents, decreased the EAG amplitude and increased the repolarization time in Spodoptera littoralis. It also modified EAG responses of Mamestra brassicae and Heliothis tea to their pheromones and analogues, containing an acetate, an alcohol or an aldehyde function. In addition, OTFP also reduced the amplitude of the EAG response to linalool, a monoterpenic alcohol, but not its kinetics. The responses of male S. littoralis to the pheromone in the wind tunnel were significantly reduced after pre-exposure to vapours of OTFP. Comparison of the activity of other TFMKs and analogues with that of OTFP revealed a good agreement on EAG and behaviour. The effects of TFMKs on the EAG kinetics are discussed considering the hypothesis of an inhibition of the pheromone deactivation in the antenna.