Field response of Colorado potato beetle to enantiomeric blends of CPB I aggregation pheromone

Colorado potato beetle, Leptinotarsa decem lineata, is attracted to (S)3,7dimethyl2oxo oct6ene1,3diol [(S)CPB I], a maleproduced aggregation pheromone. Pitfall trap studies were conducted to assess the relative attraction of L. decemlineata adults to synthetic mixtures of the (S) and (R)enantiomers of the phero mone. Of the following blends that were tested: 97%(S):3%(R), 87%(S):13%(R), 73%(S):27%(R), and 50%(S):50%(R) (racemic blend), only the blend containing 97% of the (S)enantionmer was attractive in one of the experiments. Our re sults demonstrate that the behavioral response of the beetle to pheromonebaited pitfall traps is unsubstantial in general, and that enantiomeric blends containing 13% or more of the opposite (R) enantiomer disrupt response to the phero mone. Any future research as well as integrated pest management strategies that incorporate CPB I as an aggregation pheromone should utilize blends containing more than 87% optical purity of the (S)enantiomer of the pheromone.