Activity and Persistence of Synthetic and Natural Sex Attractants of the Gypsy Moth in Laboratory and Field Trials

The sex attractant emitted by virgin female Porthetria Dispar (L.) to attract the male moth for mating has been identified and synthesized recently. This compound, disparlure, has been found active, and when suitably formulated, levels as low as 0.001 μg/trap are active even after 3 months aging in the field. Activity of disparlure is extended by combining it with volatile or nonvolatile keepers. Trioctanoin is a satisfactory keeper of the nonvolatile type, and formulations with it, e.g. 5 mg with 1 μg disparlure, are highly effective for at least 3 months and are far more attractive and persistent in survey traps than the presently used extracts of virgin females. Triolein and 2 other unsaturated compounds appear to degrade disparlure, especially low lure concentrations. Several keepers of the volatile type provide good activity hut are not so suitable for use in survey traps. Volatility of disparlure lies between the volatilities of methyl palmitate and 1,2-epoxyoctadecane. Effects of factors such as lure concentrations, configuration of the epoxide, keepers and keeper concentration, aging of disparlure formulations, trap capacity, and degree of insect infestation on moth captures are discussed. Disparlure did not become repellent at levels up to 1000 μg /trap. With light infestations of the moth, log-log plots of trap captures vs. concentration of attractant per trap were linear. An ether related to disparlure was synthesized and was slightly active. Cis and trans gyptol and gyplure and ricinoleyl alcohol were purified, and the pure compounds and impurities were tested; some of the materials are slightly active. None of the tested compounds or impurities masked the activity of disparlure significantly. The natural extract was studied also. After epoxidation, the hydrocarbon fraction of the natural extract of female tips was very active and persistent when mixed with trioctanoin. Addition of natural tip extract to disparlure depressed catches.