Microanalytical methodology relating to the identification of insect sex pheromones and related behavior-control chemicals.

Methods currently in use in the extraction, isolation, and identification of insect sex attractants, which are needed for use in pest control, are described briefly. Because amounts of these materials in insects are generally minute, specialized microanalytical methods and techniques have been developed to aid in the determination of their chemical structures.

Disruption of gypsy moth mating with microencapsulated disparlure.

Broadcast applications of microencapsulated disparlure at rates of 2.5 to 15.0 grams per hectare are capable of reducing successful mating of wild gypsy moths under field conditions. In test plots, population densities were as high as 32 pairs of pupae in an area of about 700 square meters.

Sex Pheromones: (E,E)-8,10-Dodecadien-1-ol in the Codling Moth.

Although (E,E)-8,10-Dodecadien-l-ol was reported to be a sex pheromone of the codling moth [Laspeyresia pomonella (L.)], its presence in the moth was questioned, mainly because it has not been isolated. A computerized search of data from gas chromatography-mass spectrometry of a partially purified extract equivalent to 45 abdominal tips of female moths produced a mass spectrum that matched that of the authentic coinpound. Other data also confirmed the presence of the compound.

Attraction of male gypsy and nun moths to disparlure and some of its chemical analogues.

The attractive power of disparlure-the sex attractant of the gypsy moth (Lymantria/Porthetria dispar)-vs. four synthetic analogous epoxides was tested in 1972 in a pine forest near Heidelberg. With two levels of concentration in the traps (2 and 20 µg), a total of 1112 nun moths (Lymantria/Porthetria monacha) and 257 gypsy moths were caught in 9 experiments. Approximately equal percentages of the two species were caught with a given compound. Disparlure was by far the most effective attractant. The other substances were between three and twenty times less effective. These experiments support the assumption that disparlure is also at least part of the sexual attractant of the nun moth. In two additional experiments, moth captures by a series of increasing disparlure concentrations (2-100 µg/trap) were determined. The catches of both species increased nonlinearly with the bait concentration. The experiments are discussed with respect to new (unpublished) electrophysiological recordings from disparlure receptor cells in both species. Special attention is given to the supposed masking effect of the disparlure precursor (an olefin). This substance is ineffective as an attractant, but has been reported to reduce the attraction of gypsy moth males to disparlure or to live females. However, the olefin elicits excitatory reactions in the same type of receptor cell that responds to disparlure and the related epoxides. Furthermore, no masking of the electrophysiological response was observed with the receptor cells when the olefin was added to disparlure.

Insect sex pheromones: minor amount of opposite geometrical isomer critical to attraction.

(Z)-II-Tetradecenyl acetate is the reported sex pheromone of European corn borer and redbanded leafroller moths. However, geometrically pure preparations of the compound are weakly attractive to these species. Presence of the E geometrical isomer in the Z is necessary for maximum sex attraction and these moths are "tuned" to respond optimally to specific proportions of Z to E. This discovery is important to considerations of moth pheromonal specificity, evolution, and in application of knowledge of the pheromones to insect-pest suppression.