Silicon enhances natural enemy attraction and biological control through induced plant defences

• Published in: Bulletin of entomological research 2010-06, Vol.100 (3), p.367-371
• Main Authors: Kvedaras, O.L., An, M., Choi, Y.S., Gurr, G.M.
• Format: Article
• Language: English
• Subjects: adjuvants; adult insects; Agriculture - methods; Agronomy. Soil science and plant productions; Animals; Arthropoda; Arthropods; Baits; Biological and medical sciences; Biological control; biological control agents; chemical treatment; Coleoptera - drug effects; Coleoptera - physiology; cucumbers; Cucumis sativus; Cucumis sativus - drug effects; Cucumis sativus - parasitology; Dicranolaius bellulus; Entomology; Fundamental and applied biological sciences. Psychology; Genetics and breeding of economic plants; Helicoverpa armigera; herbivore-induced plant volatiles; host plants; insect attractants; insect control; insect pests; Insects; integrated pest management; Larvae; Melyridae; Moths - physiology; natural enemies; odor compounds; olfactometer; Pest animals; Pest Control, Biological; Pest resistance; Pests; Plant pathology; plant pests; Plant resistance; potassium silicates; Predators; Predatory Behavior - drug effects; predatory insects; resistance mechanisms; Silicates - pharmacology; Silicon; trophic interactions; trophic relationships; Varietal selection. Specialized plant breeding, plant breeding aims
• ISSN: 0007-4853; 1475-2670
• DOI: 10.1017/S0007485309990265

Silicon (Si) is known to have a role in constitutive plant defence against arthropod pests, and recent work has illustrated involvement in induced plant defences. The present tri-trophic study tested the hypothesis that Si increases natural enemy attraction to pest-infested plants and improves biological control. Cucumber plants treated with potassium silicate (Si+) and untreated control plants (Si−) were maintained in separately vented glasshouse compartments. Y-tube olfactometer studies showed that adult Dicranolaius bellulus were significantly more attracted to Si+ plants upon which Helicoverpa armigera larvae had fed compared with Si−, pest-infested plants. Predators were not significantly more attracted to Si+ plants when comparing uninfested cucumbers. In a field experiment, we placed H. armigera-infested and uninfested Si+ and Si− cucumber plants in a lucerne stand. Removal rates of H. armigera egg baits showed predation was greater for Si+ infested plants than for other treatments. Results suggest that Si applied to plants with a subsequent pest infestation increases the plants' attractiveness to natural enemies; an effect that was reflected in elevated biological control in the field.