A pheromone analogue affects the evaporation rate of (+)‐disparlure in Lymantria dispar1. Issue 4 (9th August 2013) - Sollai, Giorgia
Abstract BACKGROUND The gypsy moth Lymantria dispar L. is a widespread pest that causes economic damage to cork oak forests. Females produce the sex pheromone (+)‐(7R, 8S)‐epoxy‐2‐methyloctadecane, known as (+)‐disparlure [(+)D], for long‐distance attraction of conspecific males. A (+)D analogue, 2‐decyl‐1‐oxaspiro[2.2]pentane (OXP‐01), neither stimulating nor attractive by itself, causes short‐time inhibition of male response in a 1:1 blend with (+)D. The authors investigated whether and how the biological activity of the natural pheromone is affected by OXP‐01 on a long‐time basis (up to 16 days), also by looking at possible physicochemical reciprocal interactions. RESULTS Blending of (+)D with OXP‐01 decreased, under low evaporation rate, the pheromone effectiveness, as assessed by electroantennogram recordings. In male trappings, within the first 24 h, OXP‐01 decreased and later enhanced the blend attractiveness, but only under high evaporation rate. Gas chromatography–mass spectroscopy indicates that quantitative retrieval of (+)D from blend cartridges is higher than for pure pheromone, and nuclear magnetic resonance measurements show that OXP‐01 produces, possibly by Van der Waals interactions, a bimolecular entity with pheromone causing retention and lengthening of its attractiveness over time. CONCLUSION The biological and physicochemical interactions between (+)D and OXP‐01 may provide valuable information for the optimisation of pheromone‐based control strategies for gypsy moths. © 2013 Society of Chemical Industry