Exploring the relationship between cranberry and its honey bee pollinators

In agriculture, the efficiency of pollinators is often talked about from the perspective of influence on plant yield.  Less often is the benefit of the plant to the pollinator considered.  This article does just that, and comes up with some interesting findings on how Vaccinium cropping systems affect the health of pollinator (specifically, honey bee) communities.

Pollen diversity collected by honey bees in the vicinity of Vaccinium spp. crops and its importance for colony development


Access to a rich diversity of flowering plants is very important for the development of honey bee colonies introduced in crops for pollination. The aim of this observational study was to determine the impact of surrounding pollen diversity on the health of honey bee colonies introduced in lowbush blueberries (Vaccinium angustifolium Ait.) in June and cranberries (Vaccinium macrocarpon Ait.) in July. The results suggest that monocultures of lowbush blueberries are not suitable for optimal brood rearing. In the blueberry environments we studied, the dominant pollen collected by honey bees were Alnus Mill. spp. and Taraxacum officinale F.H. Wigg., which are deficient in some essential amino acids. Significant reduction of brood rearing during honey bees’ stay in blueberry monocultures in June may, therefore, be explained by nutritional deficiencies. In July, the polliniferous flora in the vicinity of cranberry monocultures was poorer but of better nutritional quality. Pollen analysis allowed the identification of Brassicaceae, Trifolium L. spp., and V. macrocarpon as the three dominant taxa collected by honey bees during this period. The complete lists of plant taxa foraged by honey bees for pollen during the pollination of lowbush blueberries and cranberries are provided.

If you would like to read the article in full, here is the citation information and a link to where you can access it for free:

Girard, M., M. Chagnon, and V. Fournier. July 2012. Pollen diversity collected by honey bees in the vicinity of Vaccinium spp. crops and its importance for colony development. Botany 90 (7): 545–555.

Study suggests climate change is affecting cranberry development

Perhaps the most interesting finding of this research (at least to us as entomologists!) is the ecological mismatch potentially created between the cranberry plant and one of its established regional pests.  This could have concrete implications for pest management.

Cranberry flowering times and climate change in southern Massachusetts


Plants in wild and agricultural settings are being affected by the warmer temperatures associated with climate change. Here we examine the degree to which the iconic New England cranberry, Vaccinium macrocarpon, is exhibiting signs of altered flowering phenology. Using contemporary records from commercial cranberry bogs in southeastern Massachusetts in the United States, we found that cranberry plants are responsive to temperature. Flowering is approximately 2 days earlier for each 1 °C increase in May temperature. We also investigated the relationship between cranberry flowering and flight dates of the bog copper, Lycaena epixanthe—a butterfly dependent upon cranberry plants in its larval stage. Cranberry flowering and bog copper emergence were found to be changing disproportionately over time, suggesting a potential ecological mismatch. The pattern of advanced cranberry flowering over time coupled with increased temperature has implications not only for the relationship between cranberry plants and their insect associates but also for agricultural crops in general and for the commercial cranberry industry.

If you are interested in reading the full article, here is the publication information and a link to purchase it:

Ellwood, E.R., S.R. Playfair, C.A. Polgar, and R.B. Primack. 2013.  Cranberry flowering times and climate change in southern Massachusetts.  Int J Biometeorology. September. doi: 10.1007/s00484-013-0719-y.


New publication

In an exciting and ongoing research pursuit, Shawn and his collaborators are working on a method to precisely determine the trophic position of any organism in a given ecosystem.  The latest paper, titled “Trophic Hierarchies Illuminated via Amino Acid Isotopic Analysis” can be found in the September issue of PLOS ONE, here:


When will spring arrive??

The concept of ‘normal’ temperatures might be a thing of the past. After record warm temperatures last year, and record cold temperatures this year, tracking degree days is more crucial than ever. A degree day (DD) at its simplest is an average of the daily high and low temperature minus a developmental threshold. As DDs accumulate over the course of a summer, they can be used to predict certain events like bloom, moth flights, etc., regardless of the calendar date. Currently only the thresholds for the cranberry plant are published (lower threshold: 41°F, upper threshold: 85°F). These thresholds are used for predicting the stage of plant growth but only provide a rough estimate for insect development. We are working on determining the specific thresholds for Sparganothis fruitworm and we should have these results ready by the end of the summer (stay tuned!).

So how delayed are we? The DD accumulations calculated from March 1-May 15 for the past 6 years for Tomah, WI (41/85°F thresholds, single sine method, horizontal cutoff) are:

2008 – 369
2009 – 463
2010 – 607
2011 – 354
2012 – 832 (wow!)
2013 – 336

It seems that slowly, but surely, spring is arriving.

If you are interested in calculating your own DD accumulations, the University of California-IPM has an excellent DD calculator available on their website. Scroll down to the bottom of the page, enter your upper and lower thresholds (the default calculation methods are fine for the rough estimate) and click on calculate. You can then either enter your weather data online or upload a file.


Cranberries and Climate Change in Grow Magazine

Cranberries were featured in the latest article about the challenges that agricultural producers face in a changing climate. Rebecca Harbut and Ed Grygleski were interviewed about the unusual weather patterns that stressed the vines this past growing season. See pages 3 and 4 of the article for their contribution.

The College of Agricultural and Life Sciences, at University of Wisconsin-Madison, publishes Grow Magazine three times a year, highlighting agricultural research in Wisconsin. The University offers a free subscription, go here for the subscription form. For a pdf copy of the latest Grow issue, Spring 2013, go here.

— Liz Bosak

Cranberry Pollination Research at the University of Wisconsin

In the spring and summer of 2012, Hannah Gaines, a PhD student in the Entomology Department at the University of Wisconsin, did experiments in the field and in the greenhouse to better understand what non-bee factors may be influencing cranberry pollination.

Hannah's cages

Monitoring one of my pollination treatment cages in the field.

Hannah's greenhouse experiment

Hand pollinating cranberry plants in the greenhouse.

Hannah's greenhouse experiment

Hand pollinating cranberry plants in the greenhouse.

To learn more about her work on native pollinators, see this article.

Next Tuesday, the Steffan and Zalapa labs will be at the 2013 Cranberry School

From the Steffan lab, Annie, Liz, and Shawn will be discussing results of research projects from the 2012 field season. Juan Zalapa will be updating attendees on his genetics program. The WSCGA will be hosting their Winter Meeting and Cranberry School on January 22 and 23, 2013 at the Holiday Inn and Convention Center in Stevens Point, WI.

Other research highlights from the University of Wisconsin and UW-Extension include presentations by Rebecca Harbut, Jed Colquhoun, Jack Perry, Lisa Wasko-De Vetter, Christelle Guedot, Eric Zeldin, and Patty McManus.

Wisconsin State Cranberry Growers’ Association’s Meeting Is in 10 Days

The WSCGA will be hosting their Winter Meeting and Cranberry School on January 22 and 23, 2013 at the Holiday Inn and Convention Center in Stevens Point, WI. The Winter Meeting on January 22 features a trade-show with vendors offering products ranging from irrigation equipment to pollination services. The Cranberry School is an educational event with a series of presentations on a variety of production-related topics that spans both days.

The Pesticide Applicator Training will take place from 8:00 AM until 11:45 AM on Tuesday, January 22.

Davey Hyer and Jane Larson from the Wisconsin Department of Agriculture, Trade, and Consumer Protection with be talking about “Cranberry Farm Inspections: Strengths and Areas for Improvement.” Bill Outhouse and Walt Coussens will be discussing the use of food grade oils and grease for harvest equipment lubrication. Have truck maintenance issues? Well, Harry Newmann will be there to answer your questions. Many more subjects will be covered including safe working conditions, oil spill prevention and containment, animal damage, harvest technologies, irrigation water pH, and personal protective equipment.

Many researchers from the USDA-Agricultural Research Service, University of Wisconsin, and University of Wisconsin-Extension will be presenting at this year’s Cranberry School:

–Spotted Wing Drosophila, Sparganothis Phenology, and a new look at the flooding data, Shawn Steffan, USDA-ARS

–Carrying-on some tasty bits of the UW Cranberry Breeding Program, Eric Zeldin, UW Horticulture

–Genetics Program Update, Juan Zalapa, USDA-ARS

–Sustainability Survey, Jed Colquhoun, UW Extension

–Irrigation and Soil Moisture Monitoring, Rebecca Harbut, UW Extension

–What’s New in the Pesticide Screening Program, Jack Perry, UW Pesticide Screening Program

–Reflecting on Bud Appearance and its Role in Yield Prediction, Lisa Wasko-DeVetter, UW Horticulture Grad Student

–Pheromone Mating Disruption, Annie Deutsch, UW Entomology Grad Student

–Meet Our New Entomologist, Christelle Guedot, UW Extension

–Disease Observations from 2012, Patty McManus, UW Extension

–Targeting Red-Headed Flea Beetle Larvae, Liz Bosak, USDA-ARS

Spotted Wing Drosophila in Cranberry: Is this an Issue?

Here is an article from the Wisconsin State Cranberry Growers’ Association newsletter about recent research in the Steffan lab:

Cranberries and spotted wing Drosophila (SWD) in Wisconsin

Shawn Steffan (USDA-ARS Madison, WI), Jana Lee (USDA-ARS Corvallis, OR), Laura Lavine (Washington State University), Doug Walsh (Washington State University), Chase Metzger (Washington State University), Juan Zalapa (USDA-ARS Madison, WI), Christelle Guédot (University of Wisconsin-Madison), and Phil Pellitteri (University of Wisconsin-Madison).

This holiday season, there will be one demographic that won’t want to eat fresh cranberries: spotted wing Drosophila maggots. Drosophila suzukii, commonly known as SWD, does not appear to like cranberries very much. Following multiple replicated trials using ripe, under-ripe, and over-ripe organic Wisconsin cranberries, SWD females would not (or could not) insert eggs into under-ripe or ripe cranberries. This suggests that healthy, current-year fruit should be safe from attack.

Scaptomyza (Drosophilid)

Among the over-ripe, decaying cranberries (harvested, frozen, thawed, refrigerated) just two eggs were found among many berries, but no mature larvae were detected, and no adults emerged. Fortunately, rotting fruit don’t make it into the harvest because they generally don’t float. Decaying fruit get devoured every spring and summer by other drosophilid flies (see photograph above), various beetles, and countless hordes of mites and springtails.

While none of the SWD larvae successfully developed within the highly acidic flesh of fresh cranberries, studies using physically damaged cranberries showed that SWD could develop to adulthood. Again, these berries represented wounded, decaying fruit, not the sort of berries that would get harvested. That said, SWD populations could build within cranberry beds and potentially play a role in regional source-sink dynamics.

Unfortunately, SWD females love blueberries and raspberries—this we learned early. The good news for cranberry growers is that SWD adults have only rarely been trapped in/near cranberry beds, and in these cases, a blueberry or raspberry patch was nearby.

So, the take-home message: current-year cranberries (that aren’t damaged and/or rotting) appear to be safe from SWD attack. Conversely, last-year’s decaying bounty of unharvested cranberries may be vulnerable. SWD populations will likely be found each spring and summer in fruit-growing regions, but the risk to cranberry production seems minimal.

If you are suspicious of any infested fruit, contact your local Extension agent.

For other fruit crops, here is a list of resources that may be helpful:

University of Wisconsin Extension has released an article on Spotted Wing Drosophila, Drosophila suzukii, with several suggestions for scouting and trapping the fruit flies.

University of Wisconsin-Madison has a website about the Spotted Wing Drosophila in Wisconsin.

The University of Minnesota and Michigan State University have web pages with extensive lists of resources including a map of counties with SWD in Minnesota and Wisconsin.

North Carolina State University’s Small Fruit and Specialty Crop IPM blog

Pacific Northwest Insect Management Handbook SWD page

–Liz Bosak

Drought in Washington State May Impact Cranberry Harvest

Cranberry, a fruit native to North America, is grown primarily in Wisconsin, Massachusetts, New Jersey, Maine, Oregon, British Columbia, Quebec, and Washington. Contrary to the public’s perception from television commercials, cranberries are not grown underwater. Flooding is used periodically throughout the growing season for harvest, pest control, and frost protection. Cranberry marshes are intimately tied to their wetland areas to provide water for irrigation, frost protection, and flooding.

Wisconsin cranberry growers have avoided many negative effects of the drought but the same is not true for growers in Washington. Reduced water resources may delay or prolong the harvest. For the full Seattle Times article, go here.