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Domestication of tomato has reduced the attraction of herbivore natural enemies to pest-damaged plants
Xiaohong Li, Michael Garvey, Ian Kaplan, Baoping Li, Juli Carrillo
- Plant domestication can alter species interactions and influence novel associations among crops and insects. We performed a series of preference and performance experiments to test predator and herbivore attraction to domesticated and wild plants and to evaluate the efficacy of herbivore-induced plant volatiles (HIPVs) across a domestication gradient in tomato, including wild relatives, landraces and domesticated commercial cultivars.
- We employed a tri-trophic system consisting of the specialist lepidopteran herbivore Manduca sexta and two of its natural enemies: an egg predator, the stilt bug Jalysus wickhami, and a larval parasitoid, the wasp Cotesia congregata.
- In olfactometer trials, natural enemies consistently preferred HIPVs of wild tomatoes over domesticated cultivars, with landraces in between. Plant-domestication effects were also apparent in terms of decision speed: predators were slower to orient towards damaged crops than to damaged wild relatives.
- By contrast, M. sexta moths were more likely to oviposit on domesticated than on wild or landrace tomatoes, indicating that insect responses to plant odours vary with trophic level. Field trials confirmed olfactory preference tests: caterpillars recovered from wild tomato relatives were more likely to be parasitized than those recovered from landraces or domesticated tomatoes.
- The results of the present study suggest that tomato domestication has reduced the efficacy of HIPVs in attracting predators compared with wild relatives and also that this decreased attraction leads to lower attack rates by enemies in the field. This outcome has implications for understanding the specificity of tri-trophic plant defences and the compatibility of natural enemies for biocontrol in agro-ecosystems.
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