Evaluation of Supplemental Flowering Plant Strips for Sustainable Enhancement of Beneficial Insects

The primary short-term goal of this graduate student grant project was to test a strategy for utilization of  native plants to increase biodiversity in a perennial fruit system. This project is of particular relevance to specialty crop farmers that are under pressure to reduce pesticide inputs while also producing the highest quality food. Walton was concerned that these crops are becoming more important in the North Central Region as commercial farms diversify, small farms are established to supply fresh food to local markets, and the public increasingly values fresh  produce grown near to the point of sale. Walton tested whether sown native flower strips could support beneficial insects and thereby provide greater pest control and pollination in specialty crop landscapes, with the aim of building a foundation for more effective conservation of natural enemies and pollinators in the region. 

Impact of Results/Outcomes

Walton compared blueberry fields with native perennial flower plantings on their perimeters to fields without flower perimeters in order to determine theimpact of this conservation strategy on beneficial insects in crop fields. They found significantly more pollinators and natural enemies of crop pests in the fields adjacent to wildflower plantings. Natural enemies (mostly parasitoid wasps) were especially impacted by the presence of flowers, and were found in greater abundance in fields with flower plantings even 40 meters inside fields. Also, a late-season recovery of natural enemies following pre-harvest insecticide applications was seen only in fields adjacent to wildflower plantings. Native perennial wildflower conservation plantings, such as those evaluated by this research, have tremendous potential for benefiting society, the environment, and agricultural sustainability. For the grower, they can reduce erosion, encourage beneficial insects, and improve the aesthetic value of their land. For the environment, they can reduce pesticide and nutrient runoff, provide wildlife refuge, and reduce the impact of pesticide drift. All of the above in turn benefit society by improving human welfare and ensuring a sustainable food supply. We expect that as more research and  ducation is devoted to this and similar practices more farms will incorporate them into their management strategy. 

Economic Analysis  

Estimates based on current costs of native seed  mixes range from $700 - $3000 per acre, depending on the species composition of the seed mix. The flowering plant strips evaluated in this study were approximately 1/33 of an acre and the impact was measured at the scale of a 1 acre field of blueberry. In other words, to receive the a benefit equivalent to that documented by our research a grower would need to spend between 21 and 90 dollars per acre for seed. This does not include the cost of planting, herbicide, soil preparation, etc. However, this is a one time cost if perennials are used and can be expected to provide a benefit for several years at no additional cost.

Publications/Outreach

The information gathered during this multi-year  tudy has been presented to growers in the North central region through a variety of outlets. Walton presented results at the 2008 Great Lakes Fruit, Vegetable and Farm Market Expo in Grand Rapids, MI and the 2008 Entomological Society of America annual meeting in Reno, NV. A meeting was held at one of their field sites September of 2008, attended by about 20 growers. Growers were able to see a flower planting in bloom and hear presentations by representatives of USDA-NRCS, the Xerces society, project participant Dr. Rufus Isaacs of Michigan State University, and Walton, covering topics such as native pollinator conservation and how growers can receive incentives from NRCS to plant wildlife habitat on their farms. 

Farmer Adoption

In a survey of Michigan blueberry growers in March of 2009, 17% responded yes to the question, “Do you currently have a region of your farm dedicated to beneficial insect conservation?,” 8% said that they were planning to do so, and 59% said no and that they had never considered doing so. In the same survey, 17% of the growers said that they were receiving funds from the Natural Resources Conservation  ervice (NRCS) or the Farm Services Agency (FSA), but in a follow-up question only 1 of those growers  urveyed was receiving those funds specifically for beneficial insect conservation. A new FSA program introduced in January of 2008, State Acres for Wildlife Enhancement (CRP-SAFE), provides cost-sharing, rental payments, and implementation incentives to landowners who undertake practices to restore habitats that benefit high priority species conservation. In Michigan, FSA has set a goal for SAFE of preserving 2,500 acres for pollinator conservation in 22 counties in the Western Lower Peninsula. This SARE funded research will help FSA meet this goal as more growers are made aware of the benefits of integrating flowering plants into their croplands.

Want more information? See the related SARE grant(s) GNC07-086, Evaluation of supplemental lowering plant strips for sustainable enhancement of beneficial insects.