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Wildflower companion plants increase pest parasitation and yield in cabbage fields: Experimental demonstration and call for caution

Balmer, Oliver; Géneau, Céline E.; Belz, Elodie; Weishaupt, Bettina; Förderer, Gerda; Moos, Sebastian; Ditner, Nadine; Juric, Ivan and Luka, Henryk (2014) Wildflower companion plants increase pest parasitation and yield in cabbage fields: Experimental demonstration and call for caution. Biological Control, 76, pp. 19-27.

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Online at: https://www.sciencedirect.com/science/article/pii/S1049964414000917

Summary

Monocultures typical of intensive agriculture offer ideal conditions to specialized herbivores while depriving their natural enemies of habitat and nutritional resources. The resulting release of herbivores from both bottom-up and top-down control causes pest outbreaks in economically important crops. Boosting locally occurring natural enemy populations through species-specific habitat management to restore natural herbivore control has been much advocated but remains rarely tested in the field. Here, we investigated whether adding specifically selected flowering plants to monocultures increases parasitation rates of herbivores and crop yield. We performed replicated field experiments in 2 years and found that adding cornflowers (Centaurea cyanus) into cabbage (Brassica oleracea) fields significantly increased larval and egg parasitation and egg predation of the herbivore, reduced herbivory rates, and increased crop biomass in at least 1 year. These findings show that addition of a single, well-chosen flowering plant species can significantly increase natural top-down pest control in monocultures but success is variable. This is relevant on two applied levels. First, well chosen companion plants may partially substitute pesticides in agriculture if the approach is optimized, reducing negative effects such as unspecific killing of non-target organisms, residues in food, contamination of soils and water-bodies and increasing pesticide resistances. Our results suggest that, from an agro-economical point of view, egg parasitoids or predators may be the best targets for habitat management because strong natural selection acts on larval parasitoids to keep their hosts alive for their own development. Second, the addition of non-crop vegetation to monocultures benefits biodiversity conservation directly through resource diversification and indirectly through the reduction of pesticide application that increased natural control makes possible.


EPrint Type:Journal paper
Keywords:Trophic interaction, Parasitoid, Floral subsidy, Wildflower strip, Microplitis, Mamestra, functional agrobiodiversity, vegetable growing, cabbage
Subjects: Crop husbandry > Production systems > Vegetables
Environmental aspects > Biodiversity and ecosystem services
Crop husbandry > Crop health, quality, protection
Research affiliation: Germany > University of Berlin - HU
Switzerland > FiBL - Research Institute of Organic Agriculture Switzerland > Entomolgy
UK > Other organizations
Switzerland > Other organizations
DOI:https://doi.org/10.1016/j.biocontrol.2014.04.008
Deposited By: Luka, Dr. Henryk
ID Code:36391
Deposited On:26 Aug 2019 11:51
Last Modified:26 Aug 2019 11:53
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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