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Nectar exploitation by herbivores and their parasitoids is a function of flower species and relative humidity.

Winkler, Karin and Wäckers, Felix L. and Kaufman, Leyla V. and Larraz, Virginia and van Lenteren, Joop C. (2009) Nectar exploitation by herbivores and their parasitoids is a function of flower species and relative humidity. Biological Control, 50 (3). pp. 299-306. ISSN 1049-9644

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Abstract

In conservation biological control, diversification of the agro ecosystem with flowering vegetation is seen as an important tool to support the broad range of predators and parasitoids that require nectar and pollen sources to survive and reproduce. In order to identify flowering plants that provide suitable food sources for natural enemies without supporting the pest species, we analyzed the exploitation of 19 flowering plants by two important lepidopteran cabbage pests, Pieris rapae and Plutella xylostella, and their hymenopteran parasitoids, Cotesia glomerata and Diadegma semiclausum. The experiments were conducted at 90% r.h., while Pieris rapae was tested both at 45% r.h. and at 90% r.h. At 45 ± 5% r.h., corresponding with field conditions at which P. rapae is predominantly active, the butterfly was unable to feed on a number of exposed floral nectar sources whose nectar was successfully exploited at 90% r.h. The broader nectar exploitation by P. rapae at the high humidity is presumably explained by the resulting decrease in nectar viscosity. When comparing D. semiclausum and its herbivorous host P. xylostella, the herbivore exploited a broader range of plants. However, those plants that benefited both the parasitoid and the herbivore had a much stronger effect on the longevity of the parasitoid. The results from the accessibility bioassay suggest that flowers where nectar is not accessible can have a negative impact on insect survival presumably by stimulating foraging without providing accessible nectar. Our results underline the importance of considering species-specific environmental conditions when fine-tuning the choice of nectar sources to be used in conservation biological control programs.

Item Type: Article
Journal or Publication Title: Biological Control
Uncontrolled Keywords: Conservation biological control ; Nectar ; Cabbage ; Pieris rapae ; Plutella xylostella ; Cotesia glomerata ; Diadegma semiclausum ; Herbivore ; Parasitoid ; Accessibility ; Longevity ; Selectivity
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments:
ID Code: 28206
Deposited By: Mr Richard Ingham
Deposited On: 16 Nov 2009 14:05
Refereed?: Yes
Published?: Published
Last Modified: 23 Jul 2014 14:50
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/28206

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