Risk assessment of Hass avocado and Mexican Lauraceae for attack by redbay ambrosia beetle (Coleoptera: Curculionidae: Scolytinae)

Authors: Kendra, Paul; LARISSA, GUILLEN - Institute De Ecologia - Mexico; Tabanca, Nurhayat; Montgomery, Wayne; Schnell, Elena; DEYRUP, MARK - Archbold Biological Station; Cloonan, Kevin

Submitted to: Agricultural and Forest Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2022
Publication Date: 1/12/2023
Citation: Kendra, P.E., Larissa, G., Tabanca, N., Montgomery, W.S., Schnell, E.Q., Deyrup, M.A., Cloonan, K.R. 2023. Risk assessment of Hass avocado and Mexican Lauraceae for attack by redbay ambrosia beetle (Coleoptera: Curculionidae: Scolytinae). Agricultural and Forest Entomology. 25(2): 285-302. https://doi.org/10.1111/afe.12551.
DOI: https://doi.org/10.1111/afe.12551

Interpretive Summary: The redbay ambrosia beetle (RAB) is an invasive wood-borer first detected in Georgia in 2002, but since has spread to 11 additional states. Females carry fungal spores that are transferred to host trees during gallery excavation. These spores develop into fungal gardens which provide food for RAB; however, the fungus causes laurel wilt, a lethal disease of avocado, redbay, sassafras and other U.S. trees in the laurel family. With continued spread through Texas, RAB will likely enter Mexico. In advance of this event, scientists from the USDA-ARS (Miami, FL) and Instituto de Ecología (Veracruz, Mexico) conducted research to assess the risk posed to Hass avocado (the major variety grown in Mexico) and to 8 native Mexican laurels. Studies included field tests to determine RAB attraction, lab tests to assess boring behavior, and chemical analyses to correlate wood volatiles with RAB attraction. Results indicated that Hass avocado and 2 native laurels (Persea schiedeana and Ocotea sp.) are highly attractive, elicit strong boring responses, and emit known attractant chemicals (a-copaene and a-cubebene). This information facilitates development of predictive models for Mexican laurels at risk for RAB attack, and emphasizes the need for effective, early detection systems for this invasive pest in Mexico, particularly in the avocado production areas.

Technical Abstract: trees in the Lauraceae. Since first detected in Georgia, U.S.A. in 2002, this invasive pest has become established in eleven additional states. With continued spread, X. glabratus will likely enter Mexico. In advance of such an event, the current study was initiated to assess the risk posed to eight native laurels and Hass avocado, the predominant cultivar grown commercially in Mexico. Wood bolts from each species were used as substrates in (a) field tests to determine relative attraction of female X. glabratus, (b) laboratory bioassays to evaluate boring preferences, and (c) GS-MS analyses to identify host kairomones. For comparison, tests also included control bolt treatments consisting of silkbay (an attractive U.S. laurel) and Simmonds avocado (a Florida cultivar susceptible to laurel wilt). Hass avocado and two native laurels (Persea schiedeana and Ocotea sp.) were found to be highly attractive to females and elicited strong boring responses. These species were high in sesquiterpene hydrocarbons, including a-copaene and a-cubebene. Results of this study suggest that X. glabratus could become a serious agricultural and forest pest upon incursion into Mexico, with potentially severe economic and ecological impact.