Volatile Profiles of Almonds and Pistachios and Their Sex-Specific Detection by Navel Orangeworm Moths

The navel orangeworm (Amyelois transitella) is a major pest of almonds and pistachios in California, causing crop damage and facilitating fungal and mycotoxin contaminations. This study characterized volatile compounds emitted from almond- and pistachio-derived materials, including kernels, shells, hulls, and mummies, and evaluated their ability to elicit antennal responses in male and female moths using electroantennography. Volatiles were collected using solid-phase microextraction, Tenax adsorption, and solvent or steam-distillation, and analyzed by gas chromatography-mass spectrometry. Eighty-eight volatile compounds were identified, including 50 not previously reported from almond or pistachio emissions, and 80 compounds were tested for antennal activity. Male antennae responded significantly stronger to alkenes and carboxylic acids, particularly C8-C14 carbon-chain compounds. Notably, the strongest antennal responses were elicited by low-abundance components of the volatilome, indicating heightened sensitivity to minor odorants. These findings provide a chemical basis for developing improved semiochemical-based tools for navel orangeworm monitoring and management.