Optimization of blends of synthetic sex pheromone components for attraction of the sorghum plant bug Stenotus rubrovittatus (Matsumura) (Heteroptera: Miridae)

Abstract

Three components, hexyl butyrate (=butanoate) (6:nBu), (E)-4-oxohex-2-enal (E2O4-6:Ald) and (E)-hex-2-en-1-yl butyrate (E2-6:nBu), were identified as sex attractant pheromone components of the sorghum plant bug Stenotus rubrovittatus (Matsumura) (Heteroptera: Miridae) in a previous study. The optimum ratio and amount of the three components loaded into rubber septa for male attraction were investigated. A 5:10:1 blend of 6:nBu, E2O4-6:Ald and E2-6:nBu at 64 μg per rubber septum was most effective for male attraction and regarded as an 'optimized blend'. The attractiveness of the optimized blend lures did not differ between lures with and without a sunshade and was equal to that of 10 unmated females. The attractiveness of optimized blend lures after weathering for 14 d did not differ from fresh lures, whereas the attractiveness of optimized blend lures weathered for more than 21 d was lower than fresh lures. Female extracts of S. rubrovittatus contain 13 minor components; however, the attractiveness of lures impregnated with female extracts did not differ from optimized blend lures. This result suggests that minor components at the amounts contained in the female extract do not strongly enhance its attractiveness.