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Plant volatiles mediate tritrophic interactions

barley, aphids and ladybirds

Ninkovic, Velemir (2002). Plant volatiles mediate tritrophic interactions. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae. Agraria, 1401-6249 ; 321
ISBN 91-576-6152-9
[Doctoral thesis]

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The effects of plant-plant interactions via volatiles (aerial allelopathy) on herbivores and their natural enemies were investigated. The model system consisted of four barley varieties, an aphid pest, Rhopalosiphum padi (L.), and a common aphid predator, ladybird, Coccinella septempunctata (L). Aerial allelopathy significantly affected plant leaf temperature and biomass allocation, favouring root growth during the vegetative period, the main period for development of R. padi populations in Swedish barley fields. There was no effect of aerial allelopathy on relative growth rate and total biomass. A decrease in biomass allocation to the leaves was compensated for by an increase in specific leaf area. Significant changes in leaf temperature and biomass allocation of responding plants showed that the allelopathic effect was systemic. The effects were strictly dependent on which genotypes were combined, and the capacity of a plant to cause allelopathic induction was not necessarily linked to its capacity to respond. The four barley cultivars used did not differ in aphid attractivity and acceptance when tested separately. In specific cultivar combinations aerial allelopathy caused significant changes in both laboratory and field experiments. The results from field and laboratory conditions were not immediately congruent. There were differences between those cultivar combinations that caused changes in leaf temperature and those that affected aphid acceptance, indicating that the aphid response was not merely an effect of temperature preference. There were no differences in olfactory attraction of aphids to different cultivars, but significant changes were induced by aerial allelopathy. Olfactometer experiments with ladybird showed that aphid-attacked plants and previously attacked plants with the aphids removed were more attractive than undisturbed aphids or undamaged plants. Olfactory cues contributed to aggregation of ladybird adults in weed-infested plots in a barley field. Adults of ladybird responded positively to a mixture of barley-weed volatiles but a more complex mechanism possibly involving aerial allelopathy cannot be excluded. It is concluded that plant/plant interaction in the barley-weed-aphid-ladybird system has a significant effect on each trophic level i.e. plant physiology and development, aphid host plant relations and the searching behaviour of a common predator.

Authors/Creators:Ninkovic, Velemir
Title:Plant volatiles mediate tritrophic interactions
Subtitle:barley, aphids and ladybirds
Series Name/Journal:Acta Universitatis Agriculturae Sueciae. Agraria
Year of publishing :April 2002
Number of Pages:32
ALLI. Ninkovic, V. Effects of plant-plant communication in barley on biomass allocation. (Manuscript). II. Pettersson, J., Ninkovic, V. & Ahmed, E. 1999. Volatiles from different barley cultivars affect aphid acceptance of neighbouring plants. Acta Agriculture Skandinavica Section B, Plant and Soil 49, 152-157. III. Ninkovic, V., Olsson, U. & Pettersson, J. 2002. Mixing barley cultivars affect aphid host plant acceptance in field experiments. Entomologia Experimentalis et Applicata, in press. IV. Ninkovic, V., Al Abassi, S. & Pettersson, J. 2001. The influence of aphid-induced plant volatiles on ladybird beetle searching behavior. Biological control 21, 191-195. V. Ninkovic, V. & Pettersson, J. 2002. Searching behaviour of the sevenspotted ladybird, Coccinella septempunctata (L.) - effects of plant-plant odour interaction. (Submitted manuscript).
Place of Publication:Uppsala
ISBN for printed version:91-576-6152-9
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:H Protection of plants and stored products > H10 Pests of plants
F Plant production > F40 Plant ecology
Subjects:Not in use, please see Agris categories
Agrovoc terms:coccinella septempunctata, rhopalosiphum padi, pests of plants, hordeum vulgare, allelopathy, olfactory organs, plant animal relations, sweden
Keywords:Coccinella septempunctata, Rhopalosiphum padi, Hordeum vulgare, aerial allelopathy, plant-plant interaction, biomass allocation, aphid acceptance, olfactory response
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ID Code:224
Department:(NL, NJ) > Dept. of Entomology (until 061231)
Deposited By: Staff Epsilon
Deposited On:07 Apr 2003 00:00
Metadata Last Modified:02 Dec 2014 10:02

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