- Fruits: apples, berries (blueberries), cherries
- Animals: bees
- Education and Training: demonstration, on-farm/ranch research, participatory research
- Farm Business Management: cooperatives, budgets/cost and returns, feasibility study, value added
- Natural Resources/Environment: biodiversity, habitat enhancement
- Pest Management: biological control
- Production Systems: agroecosystems, holistic management, organic agriculture
Comparing results from the past three years we have found that the abundance of both native bees and insect natural enemies increased while herbivorous insects did not change in crop fields adjacent to conservation strips. There were significantly more of these beneficial insects in fields and orchards adjacent to the wildflower plantings compared to those adjacent to control (unenhanced) perimeters. Measuring the ecosystem services from these beneficial insects, after two years of wildflower establishment, in the third year of measurements we found a significant increase in percent fruit set, average berry weight, number of mature seeds per berry in blueberry fields adjacent to the conservation strips, compared with the control fields. We used the average berry weight and percent fruit set to calculate a predicted fruit yield for our blueberry farms, and although not statistically significant, the fruit yield was higher in blueberry fields adjacent to the wildflower plantings. In fields adjacent to conservation strips we also found an increase in biological control of sentinel corn earworm eggs (in blueberry) and of leafminer larvae (in apple) compared to crop fields adjacent to grass field margins. The establishment of native, perennial wildflowers along the borders of crops fields in the form of conservation strips is an initially costly practice, but with time these conservation strips will lead to an increase in the number of native bees and natural enemies. Form the data collected in this project, we can conclude that this practice will ultimately increase pollination and decrease pests in adjacent crop fields.
In order to improve grower knowledge of beneficial insect identification and how to support these insects with the use of flowering plots, we provided presentations at numerous extension meetings and conference during the past three years. These presentations generally included information on beneficial insect identification and biology, establishment and maintenance of wildflower plantings, and current results from this ongoing project. At the field days we invited growers, extension agents, government agency representatives, and anyone interested beneficial insect conservation to come learn about our project. The project team surveyed growers in attendance at the field days before and after the meetings, finding that their level of knowledge of conservation practices for building biodiversity in fruit farms increased after the training. These meetings have generated much interest in the use of conservation strips to help conserve beneficial insect, with growers taking the initiative to adopt this approach on their own. Adoption of this practice is increasing in Michigan, with increasing sales of native plant seed, and greater enrollment in government programs for pollinator conservation. These include two of our project growers who are establishing additional USDA-supported plantings in their farms after seeing the results of this project.
There has been a growing interest in recent years about the economic and ecological benefits of re-incorporating natural resources into agricultural systems (Landis et al. 2000, Kleijn and Sutherland 2003, Bianchi et al. 2006), in part because of the documented declines in populations of beneficial insects (e.g. Beismeijer et al. 2006). Crop fields within the North Central Region used for fruit and vegetable production have strips of land around them that are typically mown, tilled, or treated with herbicide. These headlands are potential areas for re-integrating flowering plants to support natural enemies and pollinators, if the benefit of these practices are documented and demonstrated to growers. In a review of the response of farmland biodiversity to set-aside schemes in the Europe and North America, Van Buskirk and Willi (2004) found evidence for increases in farm biodiversity in the presence of set-aside areas that provide non-sprayed, non-tilled areas for flowering plants. Deliberate integration of flowering plants in farms has been employed to achieve similar effects in the available field margin land (reviewed by Wratten and Van Emden, 1995). Manipulation of the environment around cropped areas by establishing flowering plants can increase natural enemy populations (Long et al. 1998, Rebek et al. 2005) and provide forage for wild bees to increase their abundance (Kells et al. 2001, Buchi 2002).
Providing a broad range of flowering plants is an essential component of rebuilding a strong beneficial insect community in farmland. These insects are dependent on access to pollen and nectar for their food and reproduction, and these can only be provided by flowers. The provision of plants that flower before and after the crop is in bloom will provide resources for native bees throughout their emergence period, and will also provide some diversity of food sources within the crop monoculture. Natural enemies will also benefit from the availability of pollen and especially nectar that can be used to fuel their flight to feed on pest insects in the crop. By providing these resources close to crop fields the insects spend less time flying to search for these resources and more time engaged in the activities that will provide benefit to producers.
A well designed flowering field border would provide nectar and pollen to natural enemies of crop pests during periods when pest numbers are low, thus maintaining high populations of predators and parasites supported by provision of nutrients throughout the season (Landis et al. 2000, Büchi 2002, Ahern 2002, Sanchez 2003, Wanner et al. 2006a,b). Selection of plants to provide these resources is an important first step in development of this tactic. Funded by a recent NC-SARE Research Grant to Doug Landis, 43 species of herbaceous perennial plants adapted to grow in full sun and tolerant of varying soil moisture were evaluated at Michigan State University for their relative attraction to natural enemies (Fiedler and Landis, 2007) and pollinators (Tuell, Fiedler, Landis, and Isaacs, in review). This research was conducted in a corn-soybean dominated landscape at the MSU campus farms, and the project has identified 26 highly-ranked species out of the 43 native flowering Midwest prairie plants that were tested. The plants that received high ranks were A) highly attractive to one or more beneficial insect group and B) easy to grow and not weedy. The results from this previous work provided us with the information necessary to design a field margin treatment with flowering plants that will support beneficial insects at farms in the North Central Region. While increasing beneficial insects is seen as a valuable goal, a critical question is “Does increasing beneficial insects lead to a benefit to the grower?”. It is important to determine and understand the benefits of resource strips for reducing pests and increasing pollination in adjacent crop fields.
The North Central Region contains the nation’s largest concentration of blueberry and cherry producers and a high proportion of the eastern apple industry. By increasing the diversity and abundance of native pollinators and insect natural enemies, fruit growers will increase the long-term sustainability of their production. Through this project, by re-integrating native flowering plants with overlapping blooms into agricultural landscapes, we determined the effectiveness of relatively inexpensive seeded conservation strips to achieve increases in beneficial insect populations and the services they can provide to fruit producers. This was done at a diverse group of fruit farms (blueberry, cherry, and apple) where we established native wildflowers in the farm landscapes for evaluation to support farm productivity and enhancement of farm environmental stewardship. We hypothesized that the artificially-planted native wildflower strips will provide an economic benefit to growers by increasing local populations of beneficial insects and the services they provide. To determine how these conservation strips affect beneficial insects we used various techniques to sample insects in crop fields adjacent to established conservation strips, as well as in fields adjacent mown grass field margins as a control. We also measured pollination parameters and biocontrol of sentinel pest eggs as techniques to evaluate how ecosystem services are affected by the existence of conservation strips. This work provides some much-needed research that will help lead to recommendations for owners of agricultural lands about practices they can adopt to enhance farm biodiversity, and the degree of economic benefit they may expect in return.
Ahern, R.G., and Brewer, M.J., 2002. Effect of different wheat production systems on the presence of two parasitoids (Hymenoptera: Aphelinidae; Braconidae) of the Russian wheat aphid in the North American Great Plains. Agriculture, Ecosystems, and Environment. 92: 201-210.
Bianchi, F.J.J.A.,Booij, C.J.H., & Tscharntke, T. 2006. Sustainable pest regulation in agricultural landscapes: a review on landscape composition, biodiversity and natural pest control. Proc. R. Soc. B. 273, 1715-1727.
Büchi, R., 2002. Mortality of pollen beetle (Meligethes spp.) larvae due to predators and parasitoids in rape fields and the effect of conservation strips. Agriculture, Ecosystems, and Environment. 90:255-263.
Fiedler, A. 2006. Evaluation of native Michigan perennial plants to provide resources for natural enemies. M.S. Thesis, Michigan State University.
Gardiner, M. M., D. A. Landis, C. Gratton, C. D. DiFonzo, M. O’Neal, J. M. Chacon, M. T. Wayo, N. P. Schmidt, E. E. Mueller, and G. E. Heimpel. 2009. Landscape diversity enhances biological control of an introduced crop pest in the north-central USA. Ecological Applications 19: 143-154.
Kells, A.R., Holland, J.M., Goulson, D. 2001 The value of uncropped field margins for foraging bumblebees. Journal of insect conservation. 5: 283-291.
Kleijn, D., & Sutherland, W.J., 2003. How effective are European agri-environment schemes in conserving and promoting biodiversity? Journal of Applied Ecology. 40: 947-969.
Landis, D.A., Wratten, S.D., & Gurr, G.M., 2000. Habitat management to conserve natural enemies of arthropod pests in agriculture. Annu. Rev. Entomol. 45: 175-201.
Long, R.F., Corbett A., Lamb C., Reberg-Horton, C., Chandler J., Stimmann, M., 1998. Beneficial insects move from flowering plants to nearby crops. Calif. Agric. 52: 23-26. Michigan State University IPM Program. 2005. Financial incentives for IPM. Michigan State University IPM Program, Lansing, MI. www.ipm.msu.edu/farmbill.htm
Rebek, E.J., Sadof, C.S., & Hanks, L.M., 2005. Manipulating the abundance of natural enemies in ornamental landscapes with floral resource plants. Biological Control. 33: 203-216.
Sanchez, J.A., Gillespie, D.R., McGregor, R.R., 2003. The effects of mullein plants (Verbascum thapsus) on the population dynamics of Dicyphus hesperus (Heteroptera:Miridae) in tomato greenhouses. Biological Control 28: 313-319.
Van Buskirk, J. and Willi, Y. 2004. Enhancement of farmland biodiversity within set-aside land. Conservation Biology 18, 987-994.
Wanner, H., Gu, H., Dorn, S. 2006a. Nutritional value of floral nectar sources for flight in the parasitoid wasp, Cotesia glomerata. Physiological Entomology. 31: 127-133.
Wanner, H., Gu, H. Gunther, D., Hein, S., Dorn, S. 2006b. Tracing spatial distribution of parasitism in fields with flowering plant strips using stable isotope marking. Biological Control. 39: 240-247.
Wratten S.D. and Van Emden, H.F. 1995. Habitat manipulation for enhanced activity of natural enemies of insect pests. In: Glen, D.M., Greaves, M.P. and Anderson, H.M. (Eds.) Ecology and Integrated Farming Systems. Wiley, Chichester, pp. 117-145.
Our objectives of this project were to 1) increase pollination and reduce pest abundance in fruit crops by deploying native plant conservation strips to support native bees and natural enemies, 2) increase producer and public awareness of using flowering plant diversity in farms to support beneficial insects including natural enemies and pollinators, 3) improve producer knowledge of beneficial insect identification and biology, and 4) develop guidelines for increased implementation of insect conservation strips in farmland.