Journal of Economic Entomology (2021) 114, 2162-2171

Arthur M. Agnello, David B. Combs, Camila C. Filgueiras, Denis S. Willett and Agenor Mafra-Neto (2021)
Reduced infestation by Xylosandrus germanus (Coleoptera: Curculionidae: Scolytinae) in apple trees treated with host plant defense compounds
Journal of Economic Entomology 114 (5), 2162-2171
Abstract: The ambrosia beetle Xylosandrus germanus (Blandford) is an invasive pest that has caused tree decline and death in numerous NY dwarf apple orchards during the past ten years, despite efforts to control them using trunk sprays of chlorpyrifos or pyrethroids, either alone or combined with the repellent verbenone. From 2017 to 2019, we tested trunk applications of different repellents and plant defense compounds for protection against X. germanus in potted apple trees adjacent to infested orchards. Treatments included topical formulations of verbenone and methyl salicylate (MeSa), alone and in combination, at different rates and timings. Additional treatments evaluated included the systemic acquired resistance activators acibenzolar-S-methyl, Reynoutria sachalinensis extract, and salicylic acid. The combination verbenone+MeSa treatments had the lowest incidences of attack sites and galleries containing adults or brood, although results varied among years. In a separate trial, we found no significant difference in numbers of adults caught in ethanol-baited traps placed 5–20 m from an apple bolt treated with the verbenone+MeSa repellent, suggesting that the repellent's effect did not extend to those distances from the treated target. Cross-sectional discs of trunk tissue sampled in August were analyzed for levels of phytohormones. Quantities of ergosterol, abscissic acid, salicylic acid, jasmonic acid, methyl salicylate, methyl jasmonate, trans-cinnamic acid, and indole-3-cinnamic acid did not significantly vary across treatments; however, trees with greater beetle damage contained higher levels of jasmonic and salicylic acid, which are key molecules in plant defense pathways.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Arthur M. Agnello, Agenor Mafra-Neto

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Xylosandrus germanus	Apple (Malus)	U.S.A. (NE)