A PORTABLE EAG SYSTEM FOR THE MEASUREMENT OF PHEROMONE CONCENTRATIONS IN THE FIELD

A robust and portable apparatus for the measurement of pheromone concentrations under field conditions has been developed. It uses the insect antenna (Lobesia botrana Hb.) itself as a sensitive and specific pheromone detector. Shock-proof contact with the electrodes is maintained by fixing the antenna in a specially-shaped plexiglass holder mounted within a glass tube. This allows measurements to be made while moving the apparatus. Continuous airflow through the tube is generated by a suction pump and the incoming air can be purified by passage through a charcoal filter. This allows to readjust the offset and to calibrate the instrument by the application of pheromone pulses of known concentrations. Removal of the filter allows the direct access of ambient air over the antenna which responds by generating an electro-antennogram (EAG) as a measure of the pheromone concentration. Using the calibration curve, relative pheromone concentrations in ambient air in a vineyard can be determined. Sample measurements from areas treated with artificial pheromone for pest control are presented.