Gyplure

The preparation and use of gyplure as a gypsy moth attractant have recently been patented (22, 23). 

Gyplure, highly attractive to male gypsy moths, is readily available commercially at low cost. If used for survey alone, one pound of this material at a cost of 10 is sufficient to bait 50,000 traps per year for 300 years. However, several commercial batches showed little or no attractiveness to males in field tests, whereas others were highly active. This lack of attractiveness has been traced to the content of inactive r 5-gyplure in some batches, formed through the failure to control temperature and alkali concentrations in their preparation. 

As shown in Table I, a concentration of 20% or more crude trans--gyplure in formulations of cis-gyplurt is sufficient to cause inactivation the mechanism of this inactivation is not known. The trans- form was prepared by elaidinization of the cis isomer with nitrous acid. The propyl and butyl analogs of w-gyplure were completely devoid of activity in field tests. These results show that a cis double bond and an acetoxy group are necessary for activity (27). 

Table 1. Number of Male Gypsy Moths Caught by Cis-Gyplure Containing Various Amounts of Trans-Gyplure...

The comparative attractancy of gyplure and its homologs and analogs to male gypsy moths is shown in Table II. The natural attractant is active at 10 fig. in the laboratory and 10 fig. in the field m-gyplure is active at 10 fig. in the laboratory and 10 fig. in the field. Conversion of the gyplure double bond to the trans form causes a tremendous drop in activity (27). 

Table II. Comparative Attractancy of Gyplure and Its Homologs to Mole Gypsy Moths...

Several other 16-carbon compounds attract male gypsy moths, but their activity does not approach that of gyplure (21). Examples are 1,2-epoxyhexadecane and its hydrolysis product, 1,2-hexadecanediol. 

Volatility of the attractant molecule is an important consideration. The effectiveness of some lures over great distances implies an appreciable degree of volatility, a property that is, in part, tied to the size of the molecule. At first we believed that a compound with 11 or 12 carbon atoms was about the optimum size and this idea seemed to work with some of the fruit fly lures. A compound of this size is volatile enough to be detected but not so volatile that it would last only a short time. The finding of gyplure, the synthetic sex attractant of the gypsy moth [Porthetria dispar (L.)l, which has 20 carbon atoms... 

The search for related derivatives proved to be successful with respect to gyptol (2), which was erroneously considered to be the sex attractant of the gypsy moth by Jacobson et al. (1961). Jacobson and Jones (1962) prepared an active homologue from ricinoleyl alcohol containing two additional methylene groups in the chain (gyplure, 19). 

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