Quercivorol as a lure for the polyphagous and Kuroshio shot hole borers, Euwallacea spp. nr. fornicatus (Coleoptera: Scolytinae), vectors of Fusarium dieback

Abstract

View the peer-reviewed version (peerj.com/articles/3656), which is the preferred citable publication unless you specifically need to cite this preprint. The polyphagous shot hole borer and Kuroshio shot hole borer, two members of the Euwallacea fornicatus species complex (Coleoptera: Curculionidae: Scolytinae), are invasive ambrosia beetles that harbor distinct species of Fusarium fungal symbionts.Together with the damage caused by gallery construction, these two phytopathogenic Fusarium species are responsible for the emerging tree disease Fusarium dieback, which affects over 50 common tree species in Southern California. Host trees suffer branch dieback as the xylem is blocked by invading beetles and fungi, forcing the costly removal of dead and dying trees in urban areas. The beetles are also threatening natural riparian habitats, and avocado is susceptible to Fusarium dieback as well, resulting in damage to the avocado industries in California and Israel. Currently there are no adequate control mechanisms for shot hole borers. This paper summarizes efforts to find a suitable lure to monitor shot hole borer invasions and dispersal. Field trials were conducted in two counties in Southern California over a span of two years. We find that the chemical quercivorol is highly attractive to these beetles, and perform subsequent field experiments attempting to optimize this lure. We also explore other methods of increasing trap catch and effects of other potential attractants, as well as the deterrents verbenone and 25 no adequate control mechanisms for shot hole borers. This paper summarizes efforts to find a 26 suitable lure to monitor shot hole borer invasions and dispersal. Field trials were conducted in 27 two counties in Southern California over a span of two years. We find that the chemical 28 quercivorol is highly attractive to these beetles, and perform subsequent field experiments 29 attempting to optimize this lure. We also explore other methods of increasing trap catch and 30 effects of other potential attractants, as well as the deterrents verbenone and piperitone. 31

Host Range Expansion and Increasing Damage Potential ofEuwallaceanr.fornicatus(Coleoptera: Curculionidae) in Florida

“…However, there are indications that the presence of ethanol decreases trap captures of the E. nr. fornicatus species present in California (Dodge et al 2017). Analytical chemistry techniques sensitive to low-molecular weight compounds, such as solid phase microextraction, may further aid in identification of attractive kairomones.…”

Dispersal behaviour of Euwallacea nr. fornicatus (Coleoptera: Curculionidae: Scolytinae) in avocado groves and estimation of lure sampling range

“…nr. fornicatus (Carrillo et al ., ) and may be repellent at high doses (Dodge et al ., ; Byers et al ., ). This may be a result of their colonization behaviour with respect to attacking healthy hosts because ethanol is a volatile emitted by stressed and dying trees (Kimmerer & Kozlowksi, ).…”

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“…That evidence as well as its attraction across all three species infers that quercivorol likely serves as a Fusarium-produced kairomone that is more broadly attractive to members of the Euwallacea species complex. Quercivorol has recently been demonstrated to attract all three species in the field (Carrillo et al 2015;Dodge et al 2017).…”

“…Quercivorol has been documented as an attractant for the E. fornicatus species complex (Carrillo et al 2015;Kendra et al 2017;Dodge et al 2017). It was first reported as an aggregation pheromone for the ambrosia beetle Platypus quercivorus (Coleoptera: Platypodidae) because it attracted both males and females (Tokoro et al 2007).…”

“…#2), which was first detected in Hawaii in 1910 (Schedl 1941) and more recently in Miami-Dade County, FL in 2002(Rabaglia et al 2008; and the Kuroshio shot hole borer (KSHB) (Euwallacea sp. #5), which was first detected in San Diego County, CA in November 2013 (Eskalen et al 2013;O'Donnell et al 2015;Carrillo et al 2016;Boland 2016;Stouthamer et al 2017;Dodge et al 2017). Each of these three beetle species carry different species of symbiotic Fusarium in their mandibular mycangia (O'Donnell et al 2015;Carrillo et al 2016), and the inability of PSHB and TSHB larvae to survive when fed Fusarium from the other species suggests that isolation between species also takes place in their obligatory feeding requirements for their associated Fusarium species as well (Freeman et al 2013a).…”