Spider mites secrete proteins via their saliva that suppress the natural resistances in their host plants. This was discovered by a group of researchers under supervision of Merijn Kant and Rob Schuurink of the UvA institute for Biodiversity and Ecosytem Dynamics and the Swammerdam Institute for Life Sciences. The results were published on 18 April as a ‘featured article’ in The Plant Journal.
Spider mites are minute herbivores, about 0,5 mm in size, capable of rapidly destroying a wide range of different plants. This study shows that these herbivores can manipulate plants such that these become a better food source. Tomato plants regulate activation of diverse defensive mechanisms, such as the production of toxins, by means of two hormonal metabolic routes. Both routes are essential for plants to withstand herbivores – not only mites but also insects and even rodents.It is generally known that some herbivores are insensitive (‘resistant’) to the toxins of plants.
This new study shows that spider mites, instead of becoming resistant, simply prevent a plant from producing toxins by blocking both defense routes by means of saliva injected into the plant. Spider mites capable of performing this trick are pests on many agricultural and horticultural crops.
Villarroel CA, Jonckheere W, Alba JM, Glas JJ, Haring MA, Van Leeuwen T, Schuurink, RC, Kant MR. (2016). Salivary proteins of spider mites suppress defenses in Nicotiana benthamiana and promote mite reproduction. The Plant Journal 86: 119–131
The article forms the key chapter in the recently published thesis of Carlos Villarroel entitled: 'Molecular Sabotage of Host Plant Defenses by Spider Mites'.