Plant defences limit herbivore population growth by changing predator–prey interactions

• Published in: Proceedings of the Royal Society. B, Biological sciences Vol. 284; no. 1862; p. 20171120
• Main Authors: Kersch-Becker, Mônica F., Kessler, André, Thaler, Jennifer S.
• Format: Journal Article
• Language: English
• Published: England The Royal Society 13-09-2017; The Royal Society Publishing
• Edition: Royal Society (Great Britain)
• Subjects: Animals; Aphids; Cyclopentanes - chemistry; Ecology; Herbivory; Jasmonic Acid; Methyl Salicylate; Oxylipins - chemistry; Plant Physiological Phenomena; Plant Resistance; Plants - chemistry; Population Growth; Predation; Predator-prey interactions; Predators; Predatory Behavior; Prey; Salicylates - chemistry; Salicylic acid; Volatile Organic Compounds; herbivory; methyl salicylate; plant resistance; volatile organic compounds; aphids; jasmonic acid
• ISSN: 0962-8452; 1471-2954
• DOI: 10.1098/rspb.2017.1120

Plant quality and predators are important factors affecting herbivore population growth, but how they interact to regulate herbivore populations is not well understood. We manipulated jasmonate-induced plant resistance, exposure to the natural predator community and herbivore density to test how these factors jointly and independently affect herbivore population growth. On low-resistance plants, the predator community was diverse and abundant, promoting high predator consumption rates. On high-resistance plants, the predator community was less diverse and abundant, resulting in low predator consumption rate. Plant resistance only directly regulated aphid population growth on predator-excluded plants. When predators were present, plant resistance indirectly regulated herbivore population growth by changing the impact of predators on the herbivorous prey. A possible mechanism for the interaction between plant resistance and predation is that methyl salicylate, a herbivore-induced plant volatile attractive to predators, was more strongly induced in low-resistance plants. Increased plant resistance reduced predator attractant lures, preventing predators from locating their prey. Low-resistance plants may regulate herbivore populations via predators by providing reliable information on prey availability and increasing the effectiveness of predators.