Ecology and Evolution (2020) 10, 4375-4390

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Bram Knegt, Tomas T. Meijer, Merijn R. Kant, E. Toby Kiers and Martijn Egas (2020)
Tetranychus evansi spider mite populations suppress tomato defenses to varying degrees
Ecology and Evolution 10 (10), 4375-4390
Abstract: Plant defense suppression is an offensive strategy of herbivores, in which they manipulate plant physiological processes to increase their performance. Paradoxically, defense suppression does not always benefit the defense-suppressing herbivores, because lowered plant defenses can also enhance the performance of competing herbivores and can expose herbivores to increased predation. Suppression of plant defense may therefore entail considerable ecological costs depending on the presence of competitors and natural enemies in a community. Hence, we hypothesize that the optimal magnitude of suppression differs among locations. To investigate this, we studied defense suppression across populations of Tetranychus evansi spider mites, a herbivore from South America that is an invasive pest of solanaceous plants including cultivated tomato, Solanum lycopersicum , in other parts of the world. We measured the level of expression of defense marker genes in tomato plants after infestation with mites from eleven different T. evansi populations. These populations were chosen across a range of native (South American) and non-native (other continents) environments and from different host plant species. We found significant variation at three out of four defense marker genes, demonstrating that T. evansi populations suppress jasmonic acid- and salicylic acid-dependent plant signaling pathways to varying degrees. While we found no indication that this variation in defense suppression was explained by differences in host plant species, invasive populations tended to suppress plant defense to a smaller extent than native populations. This may reflect either the genetic lineage of T. evansi —as all invasive populations we studied belong to one linage and both native populations to another—or the absence of specialized natural enemies in invasive T. evansi populations.
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Database assignments for author(s): Martijn Egas

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Tetranychus evansi		Spain (continental)
	Tetranychus evansi		Japan
	Tetranychus evansi		Taiwan
	Tetranychus evansi		Kenya
	Tetranychus evansi		Israel
	Tetranychus evansi		Brazil (south)
	Tetranychus evansi		Spain (Canary Is.)
	Tetranychus evansi	Tomato (Solanum lycopersicum)	Spain (continental)