Quantitative analysis of contents and volatile emissions from α-copaene and quercivorol lures, and longevity for attraction of Euwallacea nr. fornicatus in Florida

Abstract

Ambrosia beetles in the cryptic species complex Euwallacea nr. fornicatus vector a fungal pathogen responsible for Fusarium dieback, a disease that impacts avocado (Persea americana), woody ornamentals, and numerous native trees in the USA (California, Florida), Israel, and other countries. Currently, these pests are detected with quercivorol lures (containing p-menth-2-en-1-ol isomers), but recent research identified an essential oil enriched in (-)-α-copaene as a new attractant. In this study, lure longevity and efficacy were assessed in three 12-week field tests conducted in Florida by deploying traps baited with quercivorol, α-copaene, and a combination of the two. A fourth test compared different formulations of quercivorol. Concurrent with field experiments, gas chromatographic analyses were conducted to quantify initial lure contents as well as volatile emissions from lures field-aged for 12 weeks. In all tests, the lure combination captured significantly more E. nr. fornicatus than the individual lures; and in two trials, synergistic attraction was observed. Field life of the combination lure was 12 weeks; longevity of single lures varied from 9 to 12 weeks. Twelve terpenoids were detected from the α-copaene-enriched oil, suggesting there may be additional attractants. Analysis of the quercivorol lure showed it contained 88% trans- and 9% cis-p-menth-2-en-1-ol. Results indicate that the combination of quercivorol and α-copaene provides a long-lasting, effective lure for early detection of E. nr. fornicatus in Florida. Further research is needed to determine which isomer of p-menth-2-en-1-ol is attractive to Florida E. nr. fornicatus, and if other members of the species complex are attracted to (-)-α-copaene.