Native Plant Conservation Strips for Sustainable Pollination and Pest Control in Fruit Crops

2011 Annual Report for LNC08-297

Project Type: Research and Education
Funds awarded in 2008: $148,837.00
Projected End Date: 12/31/2011
Region: North Central
State: Michigan
Project Coordinator:
Co-Coordinators:
Brett Blaauw
Michigan State University

Native Plant Conservation Strips for Sustainable Pollination and Pest Control in Fruit Crops

Summary

In spring 2011, the third year of this project, we sampled beneficial and pest insects within crop fields adjacent to the flower plots and those adjacent to mown grass field margins, finding significantly more beneficial insects in crop fields adjacent to wildflower plantings. Comparing results from the past three years we have found that the abundance of both pollinators and natural enemies increase while herbivorous insects did not change in crop fields adjacent to wildflower plantings, with significantly more of these beneficial insects being in crop fields adjacent to the wildflower plantings compared to those adjacent to a grass field margin. In order to determine the effects of wildflower plantings on pollination, we measured fruit yield in crop fields adjacent to the flower plots and those without flowering plots. After two years of establishment time, the third year of measurements we found a significant increase in percent fruit set and number of mature seeds in blueberry fields adjacent to the wildflower plantings. We used the average berry weight and percent fruit set to calculate an estimate of fruit yield, and although not statistically significant, the fruit yield was higher in blueberry fields adjacent to the wildflower plantings. In fields adjacent to wildflower plantings we also found an increase in biocontrol of corn earworm eggs (in blueberry) and of leafminer larvae (in apple) compared to crop fields adjacent to grass field margins.

In order to improve grower knowledge of beneficial insect identification and supporting those insects with the use of flowering plots, we presented at numerous extension meetings and conference during the past year. These presentations generally included information on beneficial insect identification and biology, establishment and maintenance of wildflower plantings, and current results from this ongoing project.

Objectives/Performance Targets

This research project has four main objectives: 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.

Accomplishments/Milestones

Objective 1. Increase pollination and reduce pest abundance in fruit crops by deploying native plant conservation strips to support native bees and natural enemies:

As with the previous two years, we continued to use a combination of observational sampling, vacuum sampling, yellow sticky cards, and pollination measurements to determine whether wildflower plantings lead to an increase in beneficial insect abundance and improved biological control and pollination services within adjacent crop fields compared to fields adjacent to grass field margins. We also added an experiment where we used corn earworm eggs to measure the biological control services in blueberry fields adjacent to wildflower plantings and fields adjacent to grass field margins.

To measure pollinator abundance during crop bloom, observations were made at each of the crop fields adjacent to the wildflower plantings and the grass field margins, recording the identity and number of flower-visiting insects (bees, flies, wasps, etc.). Compared to the 2009 results, in 2011 we observed a higher proportion of native bees visiting crop flowers (Figure 2). Comparing over a three-year period, the abundance of native bees has significantly increased over time in crop fields adjacent to wildflower plantings (Figure 3). Abundance and diversity of pollinators during crop bloom were further assessed in the fruit crops through vacuum sampling using a modified reversed-flow leaf blower. These samples are still being assessed.

To measure pollination levels in blueberry and apple, flower buds were tagged, counted, and then covered with a fine nylon mesh bag to exclude insect pollination. After bloom the number of fruit per bagged and open samples were counted to determine percent fruit set. Prior to harvest, fruit from tagged clusters at each location were collected and weighed to determine average percent fruit set, fruit weight, and number of mature seeds were counted as a measure of pollination success. Given time for the wildflowers to establish and for insects to inhabit theses areas, after the third year of this project we found a significant increase in percent fruit set and number of mature seeds in blueberry fields adjacent to the wildflower plantings (Figure 4). Average berry weight did not significantly differ between the two treatments, but there was a trend of larger berries being found in fields adjacent to wildflower plantings (Figure 4). The blueberry pollination data were used to calculate the estimated fruit yield for 2011. Although not statistically significant, the fruit yield was higher in blueberry fields adjacent to the wildflower plantings (Figure 5). It is expected that as the wildflower plantings continue to establish, the benefits observed will continue to increase. Even a slight increase in fruit yield may potentially cover the costs of establishing and maintaining these wildflower plantings.

The abundance and diversity of natural enemies and pest insects were determined in the fruit crops in each of the fields adjacent to the wildflower plantings and also those adjacent to grass field margins using observational and yellow sticky trap techniques. In 2011 we observed a diverse community of natural enemies in crop fields, which included ants, long-legged flies, and hoverflies (Figure 6). Comparing over a three-year period, the abundance of natural enemies has significantly increased over time in crop fields adjacent to wildflower plantings, and the abundance is significantly higher in fields adjacent to the plantings compared to fields adjacent to mown grass margins (Figure 7). In addition to these observations, we also sampled natural enemies within the crops using yellow sticky traps. These samples are still being assessed.

As a new experiment for the 2011 field season, during June, July, and August we used sentinel corn earworm eggs (Lepidoptera) as a prey item to determine how wildflower plantings affect biocontrol in crop fields. Although corn earworms are not pests of blueberries, eggs were killed by freezing to ensure they would not hatch and pose no threat to the crop. The eggs were glued onto cardstock squares and deployed at the five blueberry farms. Two egg cards were placed at three positions, in the wildflower planting, along the border of the crop field, and 15 m into the interior of the crop field. Egg cards were also placed at the three corresponding positions in crop fields adjacent to a grass field margin. We measured biocontrol services by comparing egg damage/removal before being placed into the field with the egg damage/removal after being in the field exposed to natural enemies for four days. The number of damaged or missing eggs was used to calculate the biocontrol services index (BSI; Gardiner et al. 2009). We calculated significantly higher BSI values and hence higher biocontrol for egg cards in the wildflower plantings and along the crop border adjacent to the wildflower plantings when compared to those in the corresponding positions in the grass field margin treatment (Figure 8.). Although it was not statistically significant, BSI for the crop interior positions was also higher in crop fields adjacent to wildflower plantings (Figure 8).

As another method to quantify the effect of wildflower plantings on biocontrol services, in the apple orchards we collected leaves infested with spotted tentiform leafminer larvae. Fifty infested leaves were collected from edge and interior rows in orchards adjacent to wildflower plantings as well as those adjacent to mown grass field margins. The infested leaves were dissected and assessed for the presence of parasitized larvae. We found a higher percent parasitism of leafminer larvae in infested leaves collected in orchards adjacent to the wildflower plantings (Figure 9).

In order to determine how pest insects respond to wildflower plantings, we also measured the community and abundance of insect herbivores in crop fields adjacent to wildflower plantings. In 2011 we found primarily Japanese beetles, leafminers, and aphids in blueberry fields (Figure 10). Comparing over a three-year period, the abundance of insect herbivores has not significantly changed over time in crop fields adjacent to wildflower plantings or in grass field margins (Figure 11). Although insect herbivores are still present, wildflower plantings do not increase herbivore abundance in crops fields.

Reference:
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.

Objective 2. Increase producer and public awareness of using flowering plant diversity in farms to support beneficial insects including natural enemies and pollinators:

In order to improve producer and public awareness of using flowering plant diversity in farms to conserve beneficial insects including natural enemies and pollinators, we presented at numerous extension meetings and conferences during the past year. These presentations included information about using wildflower plantings to support beneficial insects and current results from this SARE funded project. In February 2012, Rufus Isaacs also presented results from this project to Michigan State Representatives at a Xerces Society sponsored pollinator conservation event.

The following are the authors, titles of presentations, and the meetings we presented results from this SARE funded project at:

Rufus Isaacs, Julianna Tuell, and Brett R. Blaauw. 2011. Habitat manipulation to support integrated crop pollination. Entomological Society of America Annual Meeting in Reno, NV. Oral presentation.

Brett R. Blaauw and Rufus Isaacs. 2011. How does wildflower planting size affect insect pollinators and their delivery of pollination ecosystem services? Entomological Society of America Annual Meeting in Reno, NV. Oral presentation.

Brett R. Blaauw and Rufus Isaacs. 2011. Variation in natural enemies and biological control with the size of native wildflower plantings. Royal Entomological Society – Ento’11 in Chatham, UK. Oral presentation.

Brett R. Blaauw and Rufus Isaacs. 2011. Response of natural enemies and their ecosystem services to wildflower patch size. Entomological Society of America – North Central Branch Annual Meeting in Minneapolis, MN. Oral presentation.

Rufus Isaacs, Julianna Tuell, and Brett R. Blaauw. 2011. Integrated Pollinator Management. Van Buren Conservation District’s Farming for the Future workshop, Paw Paw, MI. Oral presentation co-author.

Brett R. Blaauw and Rufus Isaacs. 2011. Enhancing Natural Enemies in Crops Using Flowering Plants. Great Lakes Fruit, Vegetable and Farm Market EXPO in Grand Rapids, MI. Invited oral presentation.

Brett R. Blaauw and Rufus Isaacs. 2011. Conserving Native Bees in Blueberry and Other Small Fruit. Great Lakes Fruit, Vegetable and Farm Market EXPO in Grand Rapids, MI. Invited oral presentation.

Brett R. Blaauw and Rufus Isaacs. 2012. The use of wildflower plantings to conserve beneficial insects in Michigan tree fruit. Northwest Michigan Orchard and Vineyard Show, Acme, MI.

Brett R. Blaauw and Rufus Isaacs. 2012. The effect of native wildflower planting size on beneficial insects and their ecosystem services. Science, Practice & Art of Restoring Ecosystems Conference, East Lansing, MI.

Objective 3. Improve producer knowledge of beneficial insect identification and biology:

During the third year of this project, to help improve producer knowledge of beneficial insect identification and biology, we presented at numerous extension meetings. These presentations included a brief introduction to the identification of beneficial insects and the resources these insects need to thrive in agricultural settings. We also handed out an updated two-page beneficial insects guide that outlines some of the most beneficial and common natural enemies and pollinators that growers are likely to detect at their farms.

Objective 4. Develop guidelines for increased implementation of insect conservation strips in farmland:

In order to develop guidelines for increasing implementation of wildflower plantings for the conservation of beneficial insects in farmlands we have taken extensive notes on the continuing processes used in establishing maintaining wildflower plots at our farm sites. Establishing wildflower plantings can be an expensive undertaking, so it is very important that we understand costs and benefits before we can best guide growers in adopting this conservation strategy. To make sure our guidelines are clear and remain affordable for growers we also distributed questionnaires to our grower cooperators to determine how much of their time and money was put into helping us establish and maintain the wildflower plantings.

We also created a short video entitled, “A Quick Guide to Establishing Wildflower Plantings for the Conservation of Beneficial Insects,” to give growers an introduction to the benefits, establishment, and maintenance of wildflower plantings to conserve beneficial insects. The video is posted on the Isaacs Lab webpage – http://www.isaacslab.ent.msu.edu/Videos.html

Impacts and Contributions/Outcomes

After completing three years of this project giving time for wildflowers to grow and establish in the wildflower plantings, we now have data and results that appear to support our objectives. Our data show that the abundance of beneficial insects increases in crop fields adjacent to wildflower plantings over time. Our data also show that that after three years, pollination was higher in blueberry fields adjacent to wildflower plantings compared to fields adjacent to mowed grass margins. This increase in pollination led to a subsequent increase in average fruit yield at the blueberry sites. This year we also continued our good relationships and communication with our grower cooperators, and distributed information about our project and its objectives to local growers and the public through presentations and informational handouts. Convinced by the early results from this project, one of our apple grower cooperators has began work on establishing another wildflower planting at his farm.

As a way of increasing exposure of our project and spreading information and sources on insect conservation, we created a project sign for our grower cooperators (Figure 12). These signs are displayed near or within the wildflower plantings, so that visitors to the farms can get an introduction to this SARE funded project. We also had an article featured in the January issue of the Fruit Growers News – http://fruitgrowersnews.com/index.php/magazine/article/using-habitat-to-increase-pollination/ – that gave a brief description of our project and how to conserve pollinators using wildflower plantings.

Collaborators:

Dennis Hartmann

Mr.
09548 CR 215
PO Box 195
Grand Junction, MI 49056
Karlis Galens

Mr.
70788 CR 376
PO Box 195
Covert, MI 49043
Nikki Rothwell

rothwel3@gmail.com
Dr.
Michigan State University
6686 S. Center Hwy
Traverse City, MI 49684
Office Phone: 2319461510
Jerry Brandt

Mr.
304 Herman Rd.
Suttons Bay, MI 49682
Chris Bardenhagen

Mr.
7881 E. Pertner Rd
Suttons Bay, MI 49682
Denny Vanderkooi

Mr.
10821 Pierce St.
Zeeland, MI 49464
David Epstein

epstei10@msu.edu
Mr.
Michigan State University
B18 Food Safety and Toxicology Center
PO Box 195
East Lansing, MI 48824
Office Phone: 5174324766
R.J. Rant

Mr.
14810 Woodside Trail
PO Box 195
Grand Haven, MI 49417
Brett Blaauw

blaauwb1@msu.edu
Mr.
Michigan State University
202 Center for Integrated Plant Systems
East Lansing, MI 48824
Office Phone: 5174329554
Website: www.isaacslab.ent.msu.edu
Carlos Garcia Salazar

garcias4@msu.edu
Mr.
Michigan State University Extension
12220 Fillmore St.
Suite 122
West Olive, MI 49464
Office Phone: 6169944580
Steve Tennes

4648 Otto Rd
Charlotte, MI 48813
John Calsbeek

Mr.
5737 Clymer Rd
Coloma, MI 49038
Jim Koan

1431 Duffield Rd
Flushing, MI 48433