Compounds modifying male responsiveness to main female sex pheromone component of the currant borer, Synanthedon tipuliformis Clerk (Lepidoptera: Sesiidae) under field conditions

Various blends of (E,Z)-2, 13-octadecadien-1-ol acetate (E,Z2, 13-18:OAc), (Z)-13-octadecen-1-ol acetate (Z13-18:OAc) (two previously identified pheromone components of the currant borer, Synanthedon tipuliformis females), (E,Z)-, (Z,Z)-3, 13-octadecadien-1-ol acetates (E,Z- and Z,Z3, 13-18:OAc), and Z,Z-3, 13-octadecadien-1-ol (Z,Z3, 13-18:OH) were evaluated in field traps in three geographic regions. Male S. tipuliformis were attracted to E,Z2, 13-18:OAc in Tasmania, New Zealand, and Hungary. Captures were not influenced by the addition of Z13-18:OAc, tested in Tasmania and Hungary. In Hungary and New Zealand, the addition of E,Z3, 13-18:OAc to E,Z2, 13-18:OAc in a ratio of 100:3 was strongly synergistic; however, in Tasmania captures were reduced. The addition of Z,Z3,13-18:OAc to E,Z2, 13-18:OAc in a ratio of 10:11 resulted in strong inhibition of trap captures in Hungary. When Z,Z3, 13-18:OAc was added in different ratios to a 100:3 binary mixture of E,Z2, 13-18:OAc/E,Z3, 13-18:OAc in Hungary, it strongly reduced captures at, or above a ratio of 100:3:3 but no decrease was recorded at a ratio of 100:3:1. In New Zealand and Tasmania it reduced captures at a ratio of 100:3:1. Observations of behavioral responses of male S. tipuliformis in Hungary to synthetic baits in the field showed that E,Z2, 13-18:OAc by itself evoked close-range approaches to the source from only 20% of males, whereas the addition of E,Z3, 13-18:OAc in a ratio of 100:3 raised that value to 65%. Landing on the source was significant only at sources with a 100:3:0.1:3:10 blend of E,Z2, 13-18:OAc/E,Z3, 13-18:OAc/Z,Z3, 13-18:OAc/Z,Z3, 13-18:OH/Z13-18:OAc A 100:3 binary mixture of E,Z2,13-18:OAc/E,Z3, 13-18:OAc in a dose range of 10-100 microgram can he recommended for more effective field monitoring of S. tipuliformis populations in Hungary and in New Zealand. In Tasmania, at present, E,Z2, 13-18:OAc by itself is the most potent sex attractant of the species.