INHIBITION OF PHEROMONE ACTION IN SESAMIA-NONAGRIOIDES BY HALOACETATEANALOGS

The electrophysiological activity of some halogenated analogues of the major component of the sex pheromone of the com stalk borer Sesamia n onagrioides Lef. (1) is presented. The analogues comprise a series of fluoro-, chloro- and bromoacetate analogues 4-10 as well as trifluorom ethyl ketone 11. The fluoro derivatives 4-6 displayed remarkable elect ro-antennogram (EAG) intrinsic activities in comparison with the paren t acetate 1, while the remaining analogues elicited significantly lowe r response. The compounds have also been tested as inhibitors of the s ex pheromone perception in EAG and in the field. In the laboratory, fl uoro analogues 4-6 were better inhibitors than chloro derivatives 7-9, which in turn behaved similarly to the bromoacetate 10. Trifluorometh yl ketone 11, however, was a poor inhibitor of the pheromone action. I n the field, baits of mixtures of compounds 5-11 with the corn stalk b orer pheromone in 10:1 ratio inhibited the concomitant attraction of t he clover cutworm moth Scotogramma trifolii Rott., while the difluoro analogue 5, trichloroacetate 9 and trifluoromethyl ketone 11 also dimi nished the number of catches of the armyworm Mythimna unipuncta Haw. T he monofluoroacetate 4, trifluoro analogue 6 and bromo derivative 10 s ignificantly disrupted the pheromone action of the corn borer, whereas trifluoromethyl ketone 11 synergistically increased the number of mal es attracted to the pheromone trap alone. Addition of 11 to baits cont aining the corn borer pheromone caught S. nonagrioides selectively wit h regard to the other habitat-sharing species M. unipuncta and S. trif olii.