Absolute Configuration of the Spherical Mealybug Nipaecoccus viridis Sex Pheromone, γ‑Necrodyl Isobutyrate: Chemoenzymatic Synthesis and Bioassays

The spherical mealybug, Nipaecoccus viridis (Hemiptera: Pseudococcidae), is a major global pest causing feeding damage to leaves and fruits of citrus varieties, soybean, mango, pomegranate, and grapevines. Females of the mealybug release a sex pheromone that was identified recently as a mixture of γ-necrodyl isobutyrate and γ-necrodol. The identification required synthesis based on a natural source of trans-α-necrodol, of unknown chirality, obtained from essential oil of Spanish lavender, Lavandula luisieri. To determine the chirality of the sex pheromone, here, we synthesize the γ-necrodyl acetate enriched in (+)-(S)-enantiomer and separate the enantiomers using a lipase enzyme. We confirm that the natural components, both in the mealybug and in the lavender essential oil, consist of (−)-(R)-enantiomers. Bioassays conducted in the lab and field show that males are attracted to (−)-(R)-γ-necrodyl isobutyrate alone.