In agroecosystems, conservation biological control is often constrained by low availability of pollen and nectar. Although floral resources can be integrated into agricultural systems, this usually requires sacrifice of productive land. This thesis describes experiments which test the influence of floral resources provided by species which have marketable value in their own right as food or medicinal crops. Floralresource strips comprising such species were intercropped with Brassica crops at plot, field and commercial scales in replicated field experiments. The abundance and distribution of key Brassica crop pests a,nd their natural enemies in the presence of floral resources was examined. Parasitoids displayed distinct flower species preferences; Fagopyrum esculentum significantly increased parasitoid abundance. Parasitoids also responded to distance; their abundance significantly declined with increasing distance from floral strips, especially in F. esculentum, and parasitism levels declined significantly after 8 m. Borago offtcinalis also proved attractive to parasitoids and Tanacetum parthenium to Syrphidae. In addition, F. esculentum and B. offtcinalis were found to suppress the second generation of Pierid larvae at field scale. This evidence suggests that several flower species could be intercropped within a Brassica crop to promote biological pest control.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:658572 |
| Date | January 2013 |
| Creators | Key, Georgina |
| Publisher | Lancaster University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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