ABSTRACT
Trimedlure (tert-butyl 4- and 5-chloro-cis- andtrans-2-methylcyclohexane-1-carboxylate), a mixture of eight isomers, is used as an attractant for detecting and monitoring the male Mediterranean fruit fly. This paper reports the quantitative structure-activity relationship (QSAR), via CHEMX, of the eight purified isomers (racemic mixtures) of trimedlure. The relationship between structure and attractiveness is demonstrated by utilizing male medfly field catch on day 0 of the individual isomers vs. several molecular descriptors: volume, surface area, a torsion angle, and an interatomic distance.
ABSTRACT
Structure-activity relationships of naturally occurring enedials with antifeedant activity againstSpodoptera species have been extended via the synthesis and bioassay of a series of Reimer-Tiemann adducts. The activities attributed to the different chemical structures of these and other analogs interacting with the chemoreceptor site have been observed; a three-pronged mode of substrate binding via aromatic pyrrole formation, Michael addition of free sulfhydryl moieties, and van der Waals interactions of the A ring has been postulated to account for these observations.
ABSTRACT
The biological activity of analogs of the pheromone components of the European corn borer,Ostrinia nubilalis, (Z)- and (E)-11-tetradecen1-ol acetate, in which modifications were made in the terminal alkyl portion were studied in the three pheromonal types of the insect. European corn borer males respond to pheromonal stimuli at three levels of behavioral activity, i.e., short-range sexual stimulation, activation in the flight tunnel, and response in the field. Structural requirements for elicitation of response at these levels were found to be increasingly restrictive, respectively. Flighttunnel activity was induced only by compounds that had a total chain length of 13 or 14 carbons and in which branching at carbon 13 was limited to one methyl group or a cyclopropyl group. Three new analogs were active in the flight tunnel, viz., (E and (Z)-13-methyl-11-tetradecen-1-ol acetate and (Z)-12-cyclopropyl-11-dodecen-1-ol acetate. The cyclopropyl analog was the most active analog against theZZ type of the European corn borer. TheE isomer, however, was pheromonally inactive in theEE type and was shown to be a pheromone antagonist. This dissimilarity is most likely due to differences in structure of the receptors in the European corn borer strains. Analogs that were biologically active against the European corn borer were tested against the redbanded leafroller,Argyrotaenia velutinana, which also uses (Z)- and (E)-11-tetradecen-1-ol acetate as part of its pheromone. Results showed that the redbanded leafroller pheromone acceptor system is different from that of the European com borer; marginal behavioral response was elicited by only one of the new analogs. Thus, although both species use 11-tetradecen-1-ol acetate isomers as their pheromone, the mechanisms by which they are perceived are different.
