Behavioral observations and measurements of aerial pheromone in a mating disruption trial against pea moth Cydia nigricana F (Lepidoptera, Tortricidae)

Synthetic sex pheromone of the pea moth Cydia nigricana, (E,E)-8,10-dodecadien-1-yl acetate (E8,E10-12:Ac), was applied in a 3-ha pea field at a rate of 17 g/ha, in two different dispenser formulations. Aerial concentrations within pea canopy, as determined by a field electroantennogram (EAG) apparatus, were 2 and 3 ng/m(3) in the two dispenser treatments. The validity of the EAG measurements was corroborated by sampling of field air, followed by gas chromatographic quantification of E8,E10-12:Ac. Males were attracted to fresh dispensers releasing E8,E10-12:Ac plus less than 2% of the antagonistic E, Z; Z, E; and Z, Z isomers. Two days after placement, the proportion of these isomers had increased to 6%. Males were then no longer attracted to the dispensers, but were observed to fly out of the treated field. Male attraction to calling females was almost entirely suppressed, and attraction to traps baited with synthetic pheromone was significantly reduced. Larval infestation in the pheromone-treated field was 2%, compared to 36% in a control field