Biological pest control is one way of contributing to the ecological intensification of agriculture. Flower strips can encourage natural antagonists of agricultural pests. This helps to reduce pest infestation and hence damage to agricultural crops, as well as avoiding the use of plant-protection products.
For efficient and sustainable food production, agriculture depends upon various ecosystem services. In addition to soil formation and the provision of clean water, these also include the pollination of crops by insects, or the biological control of pests. It is precisely these ecosystem services, however, that are threatened by intensive management. In particular, certain plant-protection products and a simplified agricultural landscape without hedges, extensive meadows or fallow land threaten important pollinating or pest-regulating beneficials. This can make even more interventions necessary, such as the use of plant-protection products.
Promoting ecosystem services
Instead of threatening ecosystem services, modern production systems can encourage them, with a view to replacing – or at least reducing – anthropogenic inputs. For their development, antagonists of important crop pests, such as ladybirds, ground beetles or hoverflies depend upon floral resources such as pollen and nectar, as well as on undisturbed habitats. By offering these dwindling resources to beneficials, they can be encouraged and used where they are needed.
Plants for beneficials
Flower strips tailored to the needs of beneficials could represent a practical tool for farmers, helping them strengthen biological pest control in the field. This was demonstrated by trials with ‘tailored flower strips’, sown as annual strips with plant species such as cornflower, coriander, buckwheat, poppy and dill next to an arable crop. Densities of the harmful cereal leaf beetle in adjoining winter-wheat fields were 40 to 53% lower than when no flower strip was sown on the field edge. This low pest pressure actually resulted in 61% less damage to the wheat plants.
A comparable pattern could also be seen with potatoes. In fields next to tailored flower strips, the number of aphids was 75% lower on average than in fields without flower strips. Such measures make it likely that damage will remain low – below the threshold of damage beyond which plant-protection products would become necessary. In this way, tailored flower strips can help to reduce the use of plant-protection products in agriculture. This can even be cost-effective, since it can help save money whilst achieving higher yields.
The project ‘100 tailored flower strips in practice’ is currently investigating these results more closely. In order for annual flower strips to fully develop their potential, it is important for them to be well connected to perennial habitats with hedges, extensive meadows and wildflower strips; and to be combined with a management approach that protects the beneficials.
In addition to the antagonists of cereal leaf beetles and aphids, other animal as well as plant species benefit from these flowering habitats. Moreover, the diversity of hoverfly species in tailored flower strips and adjoining crops was significantly higher than in crops without flower strips. What’s more, flower strips are an aesthetic asset for agricultural landscapes.
Since 2015, farmers have been able to create ‘flower strips for pollinators and other beneficials’ as biodiversity-promoting areas (BPAs) for ecological compensation. Together with its partner institutions FiBL, HAFL and SBV, Agroscope coordinates the further development of flowering habitats in the agricultural landscape via the ‘flowering habitats’ platform.