Methyl salicylate can benefit ornamental pest control, and does not alter per capita predator consumption at close-range

Authors: Lee, Jana; Flores, Salvador; Graham, Katerina; SKILLMAN, VICTORIA - Oregon State University

Submitted to: Frontiers in Ecology and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/22/2021
Publication Date: 1/27/2022
Citation: Lee, J.C., Flores, S.M., Graham, K.V., Skillman, V.P. 2022. Methyl salicylate can benefit ornamental pest control, and does not alter per capita predator consumption at close-range. Frontiers in Ecology and Evolution. 9. Article 788187. https://doi.org/10.3389/fevo.2021.788187.
DOI: https://doi.org/10.3389/fevo.2021.788187

Interpretive Summary: Methyl salicylate (MeSA) is released by plants when insects feed on it, and can be used to attract predators and parasitoids into the field for pest control. MeSA is commercially sold as slow-release lures or as a sprays. We tested MeSA lures in ornamental fields where few studies have been done, and checked whether it increased natural enemies, reduced pests and provided crop protection. A two-year study in spruce container yards revealed more aphid parasitoids, fewer aphids on shoot tips, and less shoot-tip damage in MeSA-treated spruce during the first year. A two-year study in red maple fields revealed more predatory lady beetles and rove beetles, and parasitic wasps with MeSA. Fewer pest thrips were also captured in MeSA plots, though it is not clear whether this was due to enhanced predation or reduced colonization of the pest. Maple growth as measured by stem diameter change did not differ with MeSA use. A two-year study examining predation on brown marmorated stink bug eggs in mature ornamental stock blocks, found no consistent increase in predation. While MeSA is expected to enhance biological control by herding in natural enemies, the impacts on predator efficiency is unknown. Thus, our second objective examined how volatile presence would impact feeding rates. Predatory ground beetles, lady beetles, and lacewings consumed their prey at similar rates in the presence/absence of MeSA when food was presented directly, or when foraging in a small outdoor arenas.

Technical Abstract: Methyl salicylate (MeSA) is an herbivore-induced plant volatile widely tested for attracting natural enemies for pest control. MeSA is commercially sold as slow-release lures or as a sprays. While MeSA application has enhanced natural enemies in a numerous food crops, its ability to reduce pests for crop protection is not as frequently demonstrated. Our first objective was to test MeSA lures in ornamental fields where few studies have been done, and monitor natural enemies, pests and crop protection. A two-year study in spruce container yards revealed more aphid parasitoids, Psuedopraon sp., fewer aphids, Mindarus obliquus, on shoot tips, and less shoot-tip damage in MeSA plots during the first year. A two-year study in red maple fields revealed more predatory lady beetles and rove beetles, and parasitic Ceraphronidae, Diapriidae, and Chalcidoidea in one or both years with MeSA. Fewer pest thrips were also captured in MeSA plots, though it is not clear whether this was due to enhanced predation or reduced colonization. Maple growth as measured by stem diameter change did not differ with MeSA use. A two-year study examining predation on sentinel Halyomorpha halys eggs in various mature ornamental stock blocks, found no increase in predation except for one month, though green lacewings, lady beetles, and predatory thrips occurred more in MeSA plots in the first year. While MeSA is expected to enhance biological control by herding in natural enemies, the impacts that applied volatiles have on predator efficiency is unknown. Thus, our second objective examined how volatile presence would impact feeding rates. Carabid adults, Pterostichus melanarius, adult ladybeetles Coccinella septempunctata and Harmonia axyridis, and larval lacewings, Chrysoperla rufilabris consumed their prey at similar rates in the presence/absence of MeSA when food was presented directly, or when foraging in a small outdoor soil arena or leaflet with prey.