Formulation of highly volatile pheromone of the white grub beetle Dasylepida ishigakiensis (Coleoptera: Scarabaeidae) to develop monitoring traps

Abstract

Polyethylene tube formulation was developed for the highly volatile sex pheromone of the white grub beetle Dasylepida ishigakiensis, a serious sugarcane pest that appears above the ground for mating during a short period on Miyako Island, Okinawa, Japan. A polyethylene tube 1 cm long containing 12 mg (R)-2-butanol was found to be one of the most effective formulations for attracting and capturing male beetles when baited in a funnel trap in the field. Its attractiveness was comparable to that of a caged virgin female. Similarly prepared tubes containing (S)-2-butanol and 2-propanol showed no attractiveness. As for the enantiomeric purity of (R)-2-butanol, blending 10% or less (S)-2-butanol did not affect attractiveness, whereas no male beetles were captured with the racemic mixture. Blending (R)-2-butanol with 2-propanol in a ratio of 1 : 2 or less showed neither a synergistic nor inhibitory effect on beetle catches in the field, while the release rate of 2-propanol from the tube was approximately 50–60% of that of 2-butanol. A tube lure containing 12 mg (R)-2-butanol released ca. 50 ng of this compound per min at 20°C in the laboratory. This led to the estimation that the effective duration of this lure (>5 months) would be sufficient to cover the entire flight season of D. ishigakiensis beetles.