Effects of organic and conventional fertilizer treatments on host selection by the aphid parasitoid Diaeretiella rapae
Effects of organic and conventional fertilizer treatments on host selection by the aphid parasitoid Diaeretiella rapae
The type and quantity of fertilizer supplied to a crop will differ between organic and conventional farming practices. Altering the type of fertilizer a plant is provided with can influence a plant’s foliar nitrogen levels, as well as the composition and concentration of defence compounds, such as glucosinolates. Many natural enemies of insect herbivores can respond to headspace volatiles emitted by the herbivores’ host plant in response to herbivory. We propose that manipulating fertilizer type may also influence the headspace volatile profiles of plants, and as a result, the tritrophic interactions that occur between plants, their insect pests and those pests’ natural enemies. Here, we investigate a tritrophic system consisting of cabbage plants, Brassica oleracea, a parasitoid, Diaeretiella rapae, and one of its hosts, the specialist cabbage aphid Brevicoryne brassicae. Brassica oleracea plants were provided with either no additional fertilization or one of three types of fertilizer: Nitram (ammonium nitrate), John Innes base or organic chicken manure. We investigated whether these changes would alter the rate of parasitism of aphids on those plants and whether any differences in parasitism could be explained by differences in attractivity of the plants to D. rapae or attack rate of aphids by D. rapae. In free-choice experiments, there were significant differences in the percentage of B. brassicae parasitized by D. rapae between B. oleracea plants grown in different fertilizer treatments. In a series of dual-choice Y-tube olfactometry experiments, D. rapae females discriminated between B. brassicae-infested and undamaged plants, but parasitoids did not discriminate between similarly infested plants grown in different fertilizer treatments. Correspondingly, in attack rate experiments, there were no differences in the rate that D. rapae attacked B. brassicae on B. oleracea plants grown in different fertilizer treatments. These findings are of direct relevance to sustainable and conventional farming practices
Pope, T.W.
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Girling, R.D.
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Staley, J.T.
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Trigodet, B.
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Wright, D.J.
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Leather, S.R.
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van Emden, H.F.
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Poppy, G.M.
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2012
Pope, T.W.
45ed1744-3848-4f3f-a401-c548eebabe30
Girling, R.D.
1044dcd8-9b1a-4f9c-bd42-7aa960de5470
Staley, J.T.
10f165cb-994a-470f-a635-5a764a36f64e
Trigodet, B.
e8615ed0-17de-4f10-bd37-8960e1c8d3f5
Wright, D.J.
6d56f7af-c503-42d2-b6f0-feee56242022
Leather, S.R.
639ee9f1-38b3-49a1-b4cd-573b04220f41
van Emden, H.F.
0da1838d-7ddf-4b63-ab36-60b8c270de27
Poppy, G.M.
e18524cf-10ae-4ab4-b50c-e73e7d841389
Pope, T.W., Girling, R.D., Staley, J.T., Trigodet, B., Wright, D.J., Leather, S.R., van Emden, H.F. and Poppy, G.M.
(2012)
Effects of organic and conventional fertilizer treatments on host selection by the aphid parasitoid Diaeretiella rapae.
Journal of Applied Entomology.
(doi:10.1111/j.1439-0418.2011.01667.x).
Abstract
The type and quantity of fertilizer supplied to a crop will differ between organic and conventional farming practices. Altering the type of fertilizer a plant is provided with can influence a plant’s foliar nitrogen levels, as well as the composition and concentration of defence compounds, such as glucosinolates. Many natural enemies of insect herbivores can respond to headspace volatiles emitted by the herbivores’ host plant in response to herbivory. We propose that manipulating fertilizer type may also influence the headspace volatile profiles of plants, and as a result, the tritrophic interactions that occur between plants, their insect pests and those pests’ natural enemies. Here, we investigate a tritrophic system consisting of cabbage plants, Brassica oleracea, a parasitoid, Diaeretiella rapae, and one of its hosts, the specialist cabbage aphid Brevicoryne brassicae. Brassica oleracea plants were provided with either no additional fertilization or one of three types of fertilizer: Nitram (ammonium nitrate), John Innes base or organic chicken manure. We investigated whether these changes would alter the rate of parasitism of aphids on those plants and whether any differences in parasitism could be explained by differences in attractivity of the plants to D. rapae or attack rate of aphids by D. rapae. In free-choice experiments, there were significant differences in the percentage of B. brassicae parasitized by D. rapae between B. oleracea plants grown in different fertilizer treatments. In a series of dual-choice Y-tube olfactometry experiments, D. rapae females discriminated between B. brassicae-infested and undamaged plants, but parasitoids did not discriminate between similarly infested plants grown in different fertilizer treatments. Correspondingly, in attack rate experiments, there were no differences in the rate that D. rapae attacked B. brassicae on B. oleracea plants grown in different fertilizer treatments. These findings are of direct relevance to sustainable and conventional farming practices
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Published date: 2012
Organisations:
Environmental
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Local EPrints ID: 196935
URI: http://eprints.soton.ac.uk/id/eprint/196935
ISSN: 0931-2048
PURE UUID: 3a6aeef1-316c-473d-8125-ccdbb50ce554
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Date deposited: 16 Sep 2011 07:37
Last modified: 14 Mar 2024 04:09
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Author:
T.W. Pope
Author:
R.D. Girling
Author:
J.T. Staley
Author:
B. Trigodet
Author:
D.J. Wright
Author:
S.R. Leather
Author:
H.F. van Emden
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