Behavioral and neurosensory responses of the boll weevil,Anthonomus grandis Boh. (Coleoptera: Curculionidae), to fluorinated analogs of aldehyde components of its pheromone

Competitive field tests with -fluorinated analogs of compounds III and IV (III--F and IV--F, respectively) of the boll weevil,Anthonomus grandis Boh., aggregation pheromone showed these compounds, when combined with the other pheromone components [(±)-I and II], to be as attractive as grandlure [(+)-I, II, and III+IV]. Dose-response curves constructed from electroantennograms of male boll weevils to serial stimulus loads of III, IV, III--F, IV--F, and the corresponding acyl fluorinated analogs (III-acyl-F and IV-acyl-F) showed the -fiuorinated analogs to be as active as the pheromone components (threshold=0.1 g), while the acyl fluorinated analogs had a 10-100 x higher threshold (=1-10 g). Single-neuron recordings showed that IV neurons and II neurons (Dickens, 1990) responded to IV--F and III--F, respectively, while IV-acyl-F and III-acyl-F were inactive. Since a previous study showed compounds I, II, and IV to be essential for behavioral responses in the field, it seems likely that the activity of the -fluorinated analogs observed here is due to the stimulation of IV neurons by IV--F as indicated in single neuron recordings.