08
Feb
Intermediary Strips of Wildflowers across Fields Reduces Pesticide Use
(Beyond Pesticides, February 8, 2018) New trials are being launched in the United Kingdom (UK) to monitor fields that have long strips of wildflowers planted through croplands to boost natural predators and potentially reduce pesticide spraying. The large-scale trials are meant to determine how effective these strips can be as a tool for practitioners wishing to enhance biological pest control in the field.
The field trials, carried out by the Centre for Ecology and Hydrology (CEH), are being conducted on 15 large arable farms in central and eastern England and would be monitored for five years. Until now, wildflower strips have been placed at the edge of fields as refuges. However, natural predators in these strips would be unable to access the center of large planted fields, and thereby unable to effectively target pests that are in the fields. In the new trials, six-meter wide strips of annual wild and cultivated plants – with 13 to 16 species – will be planted 100 meters apart so that predators will be able to attack aphids and other pests typically found in fields.
The researchers at CEH’s ASSIST program (Achieving Sustainable Agricultural Systems) will determine whether in-field strips are feasible tools for practitioners wishing to enhance biological pest control in the field. The most important focus is on supporting diverse communities of predatory and parasitic insects that kill pests. Research increasingly suggests that complex communities of predators and parasitoids are the most effective at controlling pests. Researchers will also be looking out for any sign that drawing the wild insects into the center of fields, and therefore closer to where pesticides are sprayed does more harm than good.
Resources provided by in-field strips and normal field margins benefit the greatest diversity of important predators. According to Ben Woodcock, PhD, ecological entomologist at CEH, sowing specific grasses and wildflowers in the field can support predators in the crop canopy or those that target internal pests living in stems or seed pods. Many parasitic wasps, for instance, need access to open flowers so that they can feed on pollen and nectar. Without this resource, the number of eggs they can lay is dramatically reduced and with it pest control.
Concern over the environmental damage caused by pesticides has grown rapidly in recent years, especially with the drastic decline in pollinator populations. Using wildflower margins to support insects including hoverflies, parasitic wasps and ground beetles have been shown to slash pest numbers in crops and even increase yields. Similar fields are underway in other parts of Europe where flowers such as cornflowers, coriander, buckwheat, poppy and dill are planted in strips. According to reports, densities of leaf beetle pests in fields of winter wheat were 40 to 53% lower than when no flower strips were sown. This low pest pressure even resulted in a 61% reduction in damage to the wheat plants.
Strips of flowering plants, especially with plants attractive to beneficial insects like pollinators, have been used to increased biodiversity on farms and provide refuge for these insects. Flower strips are also designed to provide early season pollen and nectar resources for important crop pollinators, such as bumblebees and solitary bees. In this respect, they provide dual benefits – enhanced natural pest control and crop pollination. In order for annual flower strips for beneficials to be fully maximized, it is important for them to be well integrated into linked perennial habitats with hedgerows, low-input meadows and wildflower strips, and secondly, for them to be combined with a management approach that protects beneficials. This also means protecting them from harmful pesticides. Previous research has shown that hedgerows improve a farm’s ecology and reduce the need for pesticides. Read Beyond Pesticides’ Hedgerows for Biodiversity: Habitat is needed to protect pollinators, other beneficial organisms, and healthy ecosystems.
Dr. Woodcock notes that strips can be easy to manage and readily re-established in another field or location in the same field. With GPS-linked farm machinery allowing the exact location of these strips to be known, this can reduce the chances of accidental spraying of the strips.
To attract beneficial insects and protect their habitats in your own backyard, there are several steps you can take. Like any other living organism, pollinators need food, water, and shelter in order to thrive. For more information, see Managing Landscapes with Pollinators in Mind
Source: The Guardian, CEH Blog
