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

Authors: OWENS, DAVID - Orise Fellow; Kendra, Paul; Tabanca, Nurhayat; Narvaez, Teresa; Montgomery, Wayne; Schnell, Elena; CARRILLO, DANIEL - University Of Florida

Submitted to: Journal of Pest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2018
Publication Date: 1/3/2019
Citation: Owens, D., Kendra, P.E., Tabanca, N., Narvaez, T.I., Montgomery, W.S., Schnell, E.Q., Carrillo, D. 2019. Quantitative analysis of contents and volatile emissions from a-copaene and quercivorol lures, and longevity for attraction of Euwallacea nr. fornicatus in Florida. Journal of Pest Science. 92(1):237-252. doi:10.1007/s10340-018-0960-6.
DOI: https://doi.org/10.1007/s10340-018-0960-6

Interpretive Summary: A group of invasive ambrosia beetles, collectively called the Euwallacea nr. fornicatus species complex, transmits a fungal pathogen that causes Fusarium dieback disease in susceptible host trees, which include avocado and many native trees in the US (both California and Florida) and other countries. Currently, these pests are detected with quercivorol lures, but recent ARS research identified an oil rich in a-copaene as a new attractant. In this study, scientists from the ARS Subtropical Horticulture Research Station (Miami, FL) and the University of Florida (Homestead) conducted field tests to evaluate the longevity and efficacy of these two lures, alone and in combination, for pest detection in Florida avocado groves. In addition, lab tests were performed to analyze volatile emissions from the lures and relate that information to the number of beetles captured in the field. In all tests, a combination of quercivorol and copaene captured significantly more E. nr. fornicatus than either lure deployed separately; and in two trials, synergistic attraction was observed. Field life of the combination lure was 12 weeks; longevity of single lures varied from 9-12 weeks. Analysis of the lures also indicated there may be additional attractants. Results showed that a 2-component lure containing quercivorol and a-copaene is the best attractant currently known for E. nr. fornicatus, providing long lasting, effective pest detection. This information will benefit avocado growers in the US, as well as the action agencies that monitor for pest ambrosia beetles.

Technical 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) 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 (-)-a-copaene as a new attractant. In this study, lure longevity and efficacy were assessed in three 12-wk field tests conducted in Florida avocado groves by deploying traps baited with quercivorol, a-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 wks. 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 wk; longevity of single lures varied from 9-12 wk. Twelve terpenoids were detected from the a-copaene-enriched oil, suggesting there may be additional attractants. Analysis of the quercivorol lure showed it contained 88% cis- and 9% trans- p-menth-2-en-1-ol. Results indicate that the combination of quercivorol and a-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 (-)-a-copaene.