Colonization of wild herbs by insects in sown and naturally developed field margin strips and in cereal fields

Published source details Denys C., Tscharntke T. & Fischer R. (1997) Die Besiedlung von Wildkräutern durch Insekten in eingesäten und selbstbegrünten Ackerrandstreifen und im Getreideacker . Verhandlungen der Gesellschaft für Ökologie, 27, 411-418.
Share Tweet Email

Actions

This study is summarised as evidence for the following.

	Action	Category
	Create uncultivated margins around intensive arable or pasture fields Action Link
	Leave headlands in fields unsprayed (conservation headlands) Action Link
	Plant nectar flower mixture/wildflower strips Action Link

Create uncultivated margins around intensive arable or pasture fields

A replicated, controlled study in summer 1995 near Göttingen, Germany (Denys et al. 1997) found higher species richness of arthropods colonizing potted mugwort Artemisia vulgaris plants in naturally regenerated margins than in unsprayed cereal control edges. However arthropod species numbers on mugwort did not differ between any of the established margin types or between mugwort plants placed in one or six-year-old regenerated margins and mugwort plants in larger set-aside areas of the same vegetation and age. Effects of the margins on individual abundance was not clear, but polyphagous spiders of the genus Theridion were recorded in significantly higher numbers on mugwort in 6-year-old regenerated margins than in 1-year-old margins, wildflower strips and sprayed cereal edges. Besides the 1- and 6-year-old naturally regenerated margins, wildflower strips (19 species sown), Phacelia strips (P. tanacetifolia plus three species), sown cereal strips and cereal control edges were investigated. Potted mugwort plants (four pots) were placed in all margin types and the controls. Mugwort plants were visited six times in June and July to count all herbivores and their predators on the plants before being taken to the lab in September to assess all arthropods feeding inside the plants. Vegetation of all margins was surveyed in June. Results from the same study are also presented in (Denys 1997, Denys & Tscharntke 2002).
Leave headlands in fields unsprayed (conservation headlands)

A replicated, controlled study in summer 1995 investigating five field margin types plus controls in intensively managed farmland near Göttingen, Germany (Denys et al. 1997) (same study as (Denys 1997, Denys & Tscharntke 2002)) found higher species richness of arthropods colonizing potted mugwort Artemisia vulgaris plants in fertilized but unsprayed cereal strips than in the unsprayed cereal control edges. However, arthropod species numbers on mugwort did not differ between cereal strips and any of the other established margin types. Besides the cereal strips, one- and six-year-old naturally regenerated margins, wildflower strips (19 species sown), phacelia strips (Phacelia tanacetifolia plus three species), and cereal control edges were investigated. Potted mugwort plants (four pots) were placed in all margin types and the controls. Mugwort plants were visited six times in June and July to count all herbivores feeding on the plants and their predators before being taken to the lab in September to assess all arthropods feeding within the plants. Vegetation of all margins was surveyed in June.
Plant nectar flower mixture/wildflower strips

A replicated, controlled study in summer 1995 near Göttingen, Germany (Denys et al. 1997) found higher species richness of plants and arthropods colonizing potted mugwort Artemisia vulgaris and red clover Trifolium pratense plants in wildflower strips than in unsprayed cereal control edges. However, the number of arthropod species on mugwort did not differ between any of the other established margin types. The number of arthropod species colonizing red clover flower heads decreased significantly with increasing distance from wildflower strips into adjacent cereal fields, but no such decline was found for individual numbers. Two types of wildflower strips were sown either with a wildflower seed mixture (19 species) or phacelia mixture (Phacelia tanacetifolia plus three species). Other margin types were one-year-old and six-year-old naturally regenerated margins and cereal strips. Potted mugwort (four pots) and red clover (three pots) plants were placed in all margin types and the controls. Mugwort plants were visited six times in June and July to count all herbivores and their predators on the plants before being taken to the lab in September to assess all arthropods feeding inside the plants. Red clover flower heads were collected five times in June-July and dissected for arthropods living inside the plants. Vegetation of all margins was surveyed in June. Results from the same study are also presented in Denys 1997, Denys & Tscharntke 2002.