Structure, function and management of semi‐natural habitats for conservation biological control: a review of European studies

Abstract

Different semi-natural habitats occur on farmland, and it is the vegetation's traits and structure that subsequently determine their ability to support natural enemies and their associated contribution to conservation biocontrol. New habitats can be created and existing ones improved with agri-environment scheme funding in all EU member states. Understanding the contribution of each habitat type can aid the development of conservation control strategies. Here we review the extent to which the predominant habitat types in Europe support natural enemies, whether this results in enhanced natural enemy densities in the adjacent crop and whether this leads to reduced pest densities. Considerable variation exists in the available information for the different habitat types and trophic levels. Natural enemies within each habitat were the most studied, with less information on whether they were enhanced in adjacent fields, while their impact on pests was rarely investigated. Most information was available for woody and herbaceous linear habitats, yet not for woodland which can be the most common semi-natural habitat in many regions. While the management and design of habitats offer potential to stimulate conservation biocontrol, we also identified knowledge gaps. A better understanding of the relationship between resource availability and arthropod communities across habitat types, the spatiotemporal distribution of resources in the landscape and interactions with other factors that play a role in pest regulation could contribute to an informed management of semi-natural habitats for biocontrol. © 2016 Society of Chemical Industry.

Spatial diversification of agroecosystems to enhance biological control and other regulating services: An agroecological perspective

“…Moreover, a reason of the non-significant increase in natural enemies could be that such diversified systems do not necessarily provide stable habitats with nonprey resources needed for numerous natural enemies (Lundgren, 2009). Holland et al (2016) reviewed the ability of a diversity of non-crop habitats in Europe to enhance conservation biological control at the local scale. They reported that linear woody (i.e.…”

Landscape complexity promotes hoverflies across different types of semi‐natural habitats in farmland

“…The importance of SNH for biodiversity and beneficial organisms, such as natural enemies of crop pests, should depend on the habitat type and its characteristic vegetation traits as well as their proportion and spatial distribution in the surrounding landscape (Holland et al., ). In particular, SNH dominated by herbaceous vegetation are expected to considerably differ in their value for beneficial organisms compared to woody SNH (Holland et al., ).…”

“…The importance of SNH for biodiversity and beneficial organisms, such as natural enemies of crop pests, should depend on the habitat type and its characteristic vegetation traits as well as their proportion and spatial distribution in the surrounding landscape (Holland et al., ). In particular, SNH dominated by herbaceous vegetation are expected to considerably differ in their value for beneficial organisms compared to woody SNH (Holland et al., ). For example, woody SNH offer more shelter from harsh weather conditions and can therefore be particularly important for overwintering arthropods (Rusch et al., ; Sarthou, Badoz, Vaissière, Chevallier & Rusch, ), while herbaceous SNH, and especially flower strips, often provide diverse floral resources (Haaland, Naisbit, & Bersier, ; Tschumi et al., ).…”

Do flower mixtures with high functional diversity enhance aphid predators in wildflower strips?

“…Wildfl ower strips (WFS) are one of several types of habitats used by insects in agricultural landscapes (Holland et al, 2016). There is extensive evidence that, when sown at fi eld margins, WFS support a higher abundance and diversity of insects compared to adjacent crops (reviewed by Haaland et al, 2011).…”