Community of bark and ambrosia beetles (Coleoptera: Curculionidae) infesting Brazilian peppertree treated with herbicide and the volatile tree response

Authors: Wheeler, Gregory; Kendra, Paul; David, Aaron; Lake, Ellen; SIGMON, JOEY - University Of Florida; Palacios, Jean

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2021
Publication Date: 9/14/2021
Citation: Wheeler, G.S., Kendra, P.E., David, A.S., Lake, E.C., Sigmon, J., Palacios, J.N. 2021. Community of bark and ambrosia beetles (Coleoptera: Curculionidae) infesting Brazilian peppertree treated with herbicide and the volatile tree response. Environmental Entomology. 50(6):1311–1321. https://doi.org/10.1093/ee/nvab096.
DOI: https://doi.org/10.1093/ee/nvab096

Interpretive Summary: Brazilian peppertree is one of the most invasive weeds of natural and agricultural areas of Florida, Hawaii, and Texas (USA). Herbicides are the main tool used to manage populations of this weed. The insects associated with the weed have been well-studied but there are no reports of bark or ambrosia beetles. We found an outbreak of ambrosia beetles, many well-known economic pests of ornamentals, from Brazilian peppertree bolts collected at a restoration site in Florida that had been treated with herbicide (triclopyr ester). A similar collection of beetles was captured on ethanol-baited sticky traps at the site. Almost all the beetles collected emerged from bolts from trees that had been treated with herbicide. Ethanol was detected from the herbicide treated bolts suggesting this was attractive to the beetles. Other volatiles monitored from bolts were not association beetle infestation. Further studies are needed to determine if invasive populations of Brazilian peppertree treated with herbicides constitute reservoirs for pest bark and ambrosia beetles that spillover onto neighboring ornamental hosts.

Technical Abstract: Brazilian peppertree, Schinus terebinthifolia Raddi (Anacardiaceae), is one of the most invasive weeds of natural and agricultural areas of Florida, Hawaii, and Texas (USA). Herbicides are the main tool used to manage populations of this weed. Faunal inventories of the insects associated with invasive populations of the weed have mostly listed leaf feeding phytophagous, pollinator or predacious species. Among these, bark and ambrosia beetles were collected only once from S. terebinthifolia in the invaded range and there are no reports from the native range. A diverse assemblage of bark and ambrosia beetles, many well-known economic pests of ornamentals, was reared from S. terebinthifolia bolts collected at a restoration site in Florida that had been treated with herbicide (triclopyr ester). A similar collection of beetles was captured on ethanol-baited sticky traps. No beetles emerged from bolts of untreated trees, almost none emerged from those hacked with a machete (3.1 % of total), whereas nearly all the beetles collected emerged from bolts that had been treated with herbicide (62.3%) or the combination hacked and herbicide (34.6%). Ethanol was detected from the herbicide and hack & squirt treated bolts suggesting this was the attractive kairomone. However, abundant amounts of other volatiles were collected from all bolts, especially those from the hacked treatment, but no association was detected between volatile emissions and beetle infestation. Further studies are needed to determine if invasive populations of S. terebinthifolia treated with herbicides constitute reservoirs for pest bark and ambrosia beetles that spillover onto neighboring ornamental hosts.