Once bitten… caterpillar attacks allow aphids to sneak up on plants

Plants face a formidable array of attackers and have to defend themselves. In a new paper published in New Phytologist, scientists describe two surprising discoveries: that plants prioritise the protection of flowers over leaves, and that simultaneous attack by aphids, caterpillars and bacteria leaves plants vulnerable to aphids but more protected from caterpillars.

When plants come under attack, they often build up defences by increasing hormonal concentrations and producing defensive compounds that can make them less palatable to attackers. In experiments on flowering plants with different dual combinations of caterpillar, aphid, and microbe attackers, concentrations of typical plant hormones, such as jasmonates, were higher in flowers than in leaves, showing that plants prioritise their reproductive organs when under attack.

Image: Aphids of Brevicoryne brassicae and the aphid parasitoid Diaeretiella rapae on Brassicanigra flowers. Credit: Dani Lucas-Barbosa..
Aphids of Brevicoryne brassicae and the aphid parasitoid Diaeretiella rapae on Brassica nigra flowers. Credit: Dani Lucas-Barbosa.

The scientists also found that dual attack by caterpillars and bacteria left plants less able to defend themselves against attack by aphids.

“Our study sheds new light on inducible defences of flowering plants if compared with most of the research that addressed plants in the vegetative stage,” said the lead authors of the paper, Lucille Chrétien and Dr Dani Lucas-Barbosa, of Wageningen University, in The Netherlands. “We think that our study is also innovative in its approach because we quantified several phytohormones involved in plant defence and reproduction, and use multivariate analyses to examine changes in the phytohormone profile upon exposure of flowering plants to single and dual attack.”

Read the press release.

Read the paper: Chrétien, L. T. S., David, A., Daikou, E., Boland, W., Gershenzon, J., Giron, D., Dicke, M. and Lucas-Barbosa, D. (2017) Caterpillars induce jasmonates in flowers and alter plant responses to a second attacker. New Phytologist. doi: 10.1111/nph.14904

Mike Whitfield (@mgwhitfield)
Development Coordinator
New Phytologist

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