Silicon enhances natural enemy attraction and biological control through induced plant defences.
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.
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EH Graham Centre for Agricultural Innovation, New South Wales Department of Primary Industries, Private Mail Bag, Wagga Wagga, NSW 2650, Australia. olivia.kvedaras@dpi.nsw.gov.au
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D000383:Agriculture / Q000379:methods; D000818:Animals; D001517:Coleoptera / Q000187:drug effects* / Q000502:physiology; D018553:Cucumis sativus / Q000187:drug effects / Q000469:parasitology; D009036:Moths / Q000502:physiology*; D010572:Pest Control, Biological; D011235:Predatory Behavior / Q000187:drug effects*; D017640:Silicates / Q000494:pharmacology*
D017640:Silicates