Institute for Biodiversity and Ecosystem Dynamics

Spider mites are able to disarm plant defence system

3 March 2011

When herbivores such as spider mites attack a plant, complex plant defence mechanisms are activated. Dr. Renato de Almeida Sarmento of the Institute for Biodiversity and Ecosystem Dynamics (IBED) at the University of Amsterdam and of the Federal Universities of Viçosa and Tocantins, Brazil, discovered that certain spider mites are able to disrupt these mechanisms, effectively disarming the plant.

When herbivores such as spider mites attack a plant, complex plant defence mechanisms are activated. Dr. Renato de Almeida Sarmento of the Institute for Biodiversity and Ecosystem Dynamics (IBED) at the University of Amsterdam and of the Federal Universities of Viçosa and Tocantins, Brazil, discovered that certain spider mites are able to disrupt these mechanisms, effectively disarming the plant.

Plants have complex mechanisms to defend themselves against pathogens and herbivores. Some of these defences are triggered on contact with either type of threat. Such mechanisms range from structural reinforcement, e.g. thickening of the cell walls, to an increased production of toxic compounds, e.g. nicotine in tobacco plants. In the case of herbivore attack, plants may even produce volatiles that attract the herbivore’s enemy. However, the interaction between plants and herbivores is a continuous evolutionary struggle to outwit one another. Therefore, scientists have long suspected that herbivores might be able to disrupt some of the plant’s defence mechanisms.

In a recent study, Dr. Renato de Almeida Sarmento at the Population Biology Research Group of IBED was the first to produce experimental evidence of the suppression of plant defences by herbivores. With a team of international scientists, he found that the spider mite Tetranychus evansi is able to suppress the induction of defence compounds such as proteinase inhibitors in tomato plants. The spider mites do this by suppressing the induction of the salicylic and jasmonic acid signalling routes that are part of the defence mechanism. The disruption proved so effective that the levels of the defence compounds became even lower than in plants that were not under attack. As a result, the mite-infested plants became a better food source and more attractive for the mites.

The findings of Sarmento and his team shed a whole new light on plant-herbivore interactions, plant protection and plant resistance to invasive species. New insights that are not only of scientific interest, but also have important practical implications e.g. in the design and improvement of sustainable pest control systems for crops.

Publication information

The study was published in Ecology Letters 14:229-236 in February 2011 [doi: 10.1111/j.1461-0248.2010.01575.x], and is part of the PhD thesis of Sarmento entitled ‘An acarine herbivore interferes with direct and indirect plant defences’.

The article was published 'open access' making it freely accessible to all interested.

Published by  IBED