Evaluation of repellents for the redbay ambrosia beetle, Xyleborus glabratus, vector of the laurel wilt pathogen

Abstract

The redbay ambrosia beetle, Xyleborus glabratus, is the vector of the laurel wilt disease fungal pathogen, Raffaelea lauricola. Since the vector's initial detection in the USA in the early 2000s, laurel wilt has killed millions of redbay, Persea borbonia, trees and other members of the plant family Lauraceae. To protect host trees from beetle attack and laurel wilt infection, we tested the efficacy of host‐ and non‐host‐derived and commercial compounds as X. glabratus repellents in field experiments. In our first trial, the major constituents of the non‐host tree, longleaf pine, Pinus palustris, and SPLAT Verb (verbenone 10%) were paired with manuka oil attractants and beetle captures were counted. Verbenone and a 1 : 1 blend of myrcene and camphene were intermediate to both the manuka positive and blank negative controls. Subsequently, we tested different blends of methyl salicylate (MeSA), a host defence and signalling compound, and verbenone in SPLAT dispensers using freshly cut redbay bolts as an attractant. All treatments reduced X. glabratus captures and boring holes as compared to the redbay (‐) repellent positive control; however, SPLAT Verb and SPLAT MeSA‐Verb (5% each) achieved the highest repellency, with results comparable to that of the non‐host (laurel oak). These trials establish that host‐derived and commercially available repellent compounds can reduce X. glabratus attacks and therefore have potential as part of an integrated management strategy against laurel wilt and its vector.

Evaluation of semiochemical based push-pull strategy for population suppression of ambrosia beetle vectors of laurel wilt disease in avocado

“…The push-pull strategy of applying combined repellent and attractant stimuli in order to manipulate the distribution of a pest is an integrated pest management tool that has been established in several systems 39 . The use of repellents has been successful in natural stands of Laureacae against laurel wilt 27 , but in a monoculture, agricultural setting, we hypothesized that the additional pull treatment may be necessary to affect beetle populations based on our first trial where repellents alone in avocado were ineffective.…”

“…Under laboratory conditions, we assessed the repellency of verbenone and methyl salicylate on two putative vectors of R. lauricola: X. bispinatus and X. volvulus. Verbenone was selected because it has been used in multiple systems as a general bark beetle repellent and has also been proven highly effective in natural forests against the redbay ambrosia beetle, X. glabratus 27,[40][41][42][43][44] . Methyl salicylate, the other putative repellent used in our studies, is a volatile chemical commonly associated with plant stressors 45 .…”

“…SPLAT containing either 10% w/v of verbenone or MeSA was dispensed as eight individual 1 g dollops per tree using a caulk gun (HDX, Heavy Duty Caulk Gun, Home Depot, Cobb County, GA, USA) to all trees per 3 × 3 tree plot. The application dosage was based on field efficacy observed previously with release of both verbenone and MeSA in previous field studies with X. glabratus 27 .…”

Trap Tree and Interception Trap Techniques for Management of Ambrosia Beetles (Coleoptera: Curculionidae: Scolytinae) in Nursery Production

“…Neither trapping method was sufficient to protect nursery trees alone. Several studies have been undertaken to evaluate the efficacy of repellent 'push' semiochemicals like verbenone for management of ambrosia beetle pests of the nursery industry (Burbano et al 2012, Hughes et al 2017. The results of these 'push' studies have been variable across ambrosia beetle species, both spatially and temporally, and none of the investigated repellents resulted in complete protection of host trees.…”

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“…To see if we could repel SHB in the field, ChemTica Internacional provided pouches of Beetleblock Verbenone, a bark and ambrosia beetle repellent. Verbenone has been used in the past to successfully deter economically important bark beetles in the genera Ips and Dendroctonus (Borden et al 1991;Fettig et al 2009), and has more recently been utilized for ambrosia beetle pests (Burbano et al 2012;Hughes et al 2017;Jaramillo et al 2013). We tested the effect of verbenone on SHB by pairing the verbenone pouch with a quercivorol lure (Synergy Semiochemicals, Batch #3361), to determine if the repellent offset the attractiveness of quercivorol.…”