Pheromone-dependent species recognition mechanisms between Neodiprion pinetum and Diprion similis on white pine.
The sex pheromones of Neodiprion pinetum and Diprion similis consist of 2 isomers, (2S,3S,7S)- and (2S,3R,7R)-, in either the acetate or propionate forms of 3,7-dimethylpentadecan-2-yl acetate, respectively. The (2S,3S,7S)- acetate isomer is utilized by N. pinetum as the major pheromone component and the (2S,3R,7R)-acetate as a synergist. Conversely, D. similis utilizes (2S,3R,7R)-propionate as the major pheromone component and (2S,3S,7S)-propionate as a synergist. This was confirmed in the field in stands of white pine (Pinus strobus) in both Michigan and Wisconsin for N. pinetum and in only Michigan for D. similis. Capillary gas-liquid chromatographic analyses revealed that these 2 isomers are present in the natural pheromones of both species at the ratios close to those predicted by artificial blending of the 2 optical isomers.