Potential of quercetin to reduce herbivory without disrupting natural enemies and pollinators

Authors: Riddick, Eric

Submitted to: Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2021
Publication Date: 5/22/2021
Citation: Riddick, E.W. 2021. Potential of quercetin to reduce herbivory without disrupting natural enemies and pollinators. Agriculture. 11:476. https://doi.org/10.3390/agriculture11060476.
DOI: https://doi.org/10.3390/agriculture11060476

Interpretive Summary: Quercetin is an abundant phytochemical in plants and pollen. It is believed to function as a plant defensive compound against insects that attack crop plants. In this study, the hypothesis that quercetin could be used as a less-toxic, natural biocide against plant-feeding insects without harming beneficial insects was tested. The results indicated that quercetin had more harmful (than non-harmful) effects on behavior, physiology, and life history of plant-feeding insects, when data from five insect orders were combined. On the other hand, quercetin had more non-harmful (than harmful) effects on beneficial insects, including natural enemies and pollinators. This study suggests that quercetin has great potential as a natural biocide to control insect pests without disrupting the services provided by natural enemies and pollinators in cropping systems.

Technical Abstract: Quercetin is one of the most abundant flavonoids in terrestrial plants and pollen. In living plants, quercetin can function as a secondary metabolite to discourage insect herbivory. Literature on insect-quercetin interactions was searched and data synthesized to test the hypothesis that quercetin can become an effective biocide to reduce herbivory without disrupting natural enemies and pollinators. The USDA, National Agricultural Library, DigiTop Navigator platform was used to search the literature for harmful versus nonharmful effects of quercetin on insect behavior, physiology, and life history parameters. Quercetin effects were evaluated on herbivores in five insect orders, natural enemies in two orders, and pollinators in one order. Quercetin was significantly more harmful to Hemiptera, Diptera, and Lepidoptera but significantly more nonharmful to Coleoptera. Harmful and nonharmful effects to Orthoptera were indistinguishable. Quercetin had significantly more harmful (than nonharmful) effects on herbivores when data from the five insect orders were combined. Quercetin concentration (mg/mL) did not significantly affect these results. Quercetin was significantly more nonharmful to natural enemies (Coleoptera and Hymenoptera, combined) and pollinators (Hymenoptera). This study suggests that quercetin could prevent herbivory without disrupting natural enemies and pollinators, but field experiments are necessary to substantiate these results.