Ambiguous response of Riptortus clavatus (Heteroptera: Alydidae) to different blends of its aggregation pheromone components

Abstract

We investigated the attraction of Riptortus clavatus to different component compositions of its aggregation pheromone (mixture of three components) in the field by the use of sticky traps. In two-component tests, each of (E)-2-hexenyl(E)-2-hexenoate (EE) and (E)-2-hexenyl(Z)-3-hexenoate (EZ) mixed with myristyl isobutyrate (MI) showed equally synergistic effects in attracting R. clavatus relative to MI alone. There was no correlation between the degree of attractiveness and the dosages of EE or EZ added to MI. No significant difference was observed in the numbers of insects caught between traps baited with the three-component blend (MI + EE + EZ) and traps with two-component blends (MI + EE or MI + EZ). In addition, two-component blends (MI:EE or MI:EZ=2:1) were almost as attractive as the natural blend (MI:EE:EZ=1:5:1), and even in the absence of the main component, EE. R. clavatus responded to a wide range of the pheromone component blends without a particular optimum blending ratio. This might characterize the aggregation pheromone of this bug.