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Plant Cell Environ. 2016 Sep;39(9):1920-7. doi: 10.1111/pce.12752. Epub 2016 May 12.

Powdery mildew suppresses herbivore-induced plant volatiles and interferes with parasitoid attraction in Brassica rapa.

Author information

1
Institute of Biology, University of Neuchâtel, Switzerland.

Abstract

The co-occurrence of different antagonists on a plant can greatly affect infochemicals with ecological consequences for higher trophic levels. Here we investigated how the presence of a plant pathogen, the powdery mildew Erysiphe cruciferarum, on Brassica rapa affects (1) plant volatiles emitted in response to damage by a specialist herbivore, Pieris brassicae; (2) the attraction of the parasitic wasp Cotesia glomerata and (3) the performance of P. brassicae and C. glomerata. Plant volatiles were significantly induced by herbivory in both healthy and mildew-infected plants, but were quantitatively 41% lower for mildew-infected plants compared to healthy plants. Parasitoids strongly preferred Pieris-infested plants to dually-infested (Pieris + mildew) plants, and preferred dually infested plants over only mildew-infected plants. The performance of P. brassicae was unaffected by powdery mildew, but C. glomerata cocoon mass was reduced when parasitized caterpillars developed on mildew-infected plants. Thus, avoidance of mildew-infested plants may be adaptive for C. glomerata parasitoids, whereas P. brassicae caterpillars may suffer less parasitism on mildew-infected plants in nature. From a pest management standpoint, the concurrent presence of multiple plant antagonists can affect the efficiency of specific natural enemies, which may in turn have a negative impact on the regulation of pest populations.

KEYWORDS:

Cotesia glomerata; Erysiphe cruciferarum; infochemical networks; insect-plant interactions; multiple herbivory

PMID:
27043839
DOI:
10.1111/pce.12752
[Indexed for MEDLINE]

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