Great New Paper Out: Effects of Pesticides on Bees

Continuing with the pollination theme, here’s a new paper out on the topic:

Crop Pollination Exposes Honey Bees to Pesticides Which Alters Their Susceptibility to the Gut Pathogen Nosema ceranae


Recent declines in honey bee populations and increasing demand for insect-pollinated crops raise concerns about pollinator shortages. Pesticide exposure and pathogens may interact to have strong negative effects on managed honey bee colonies. Such findings are of great concern given the large numbers and high levels of pesticides found in honey bee colonies. Thus it is crucial to determine how field-relevant combinations and loads of pesticides affect bee health. We collected pollen from bee hives in seven major crops to determine 1) what types of pesticides bees are exposed to when rented for pollination of various crops and 2) how field-relevant pesticide blends affect bees’ susceptibility to the gut parasite Nosema ceranae. Our samples represent pollen collected by foragers for use by the colony, and do not necessarily indicate foragers’ roles as pollinators. In blueberry, cranberry, cucumber, pumpkin and watermelon bees collected pollen almost exclusively from weeds and wildflowers during our sampling. Thus more attention must be paid to how honey bees are exposed to pesticides outside of the field in which they are placed. We detected 35 different pesticides in the sampled pollen, and found high fungicide loads. The insecticides esfenvalerate and phosmet were at a concentration higher than their median lethal dose in at least one pollen sample. While fungicides are typically seen as fairly safe for honey bees, we found an increased probability of Nosema infection in bees that consumed pollen with a higher fungicide load. Our results highlight a need for research on sub-lethal effects of fungicides and other chemicals that bees placed in an agricultural setting are exposed to.

Pettis, J.S., E.L. Lichtenberg, M. Andree, et al. July 2013.  PLOS ONE, 8:7 Article Number: e70182   DOI: 10.1371/journal.pone.0070182

UW Kemp Research Station

Recently the Steffan lab went on the first-ever annual Steffan lab retreat at the Kemp Research station in Woodruff, WI (  It was AWESOME.  Situated on the picturesque Tomahawk Lake, we were able to enjoy the beautiful Wisconsin wilderness and check out wild cranberry.  Led by our fearless leader for the weekend, Kyle Johnson—a Lepidoptera and bog expert—we got to see some really cool stuff. 
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View from the back deck.
We visited a few different wild sites.  The first was an oligotrophic bog, which means nutrient poor.  Here the plants receive nutrients from the air instead of the ground.  The flora found here is unique to these types of highly acidic ecosystems, which is a relatively rare environmental condition so these are not plants one would come across often.
Fruiting wild cranberry (Vaccinium oxycoccos) among a bed of moss.
This was what the ground looked like, which was like walking across a spongy mat.
Wild cranberry harvest.  
Tamarack tree, a common bog tree.
Kyle collecting berries.
 Lepidoptera on leatherleaf.
More lichens (British soldiers)!
Kyle’s pet wolfspider.
Next stop was to pick up some wintergreen leaf with which to make tea to warm us up back at the station.  The ground here was pretty much covered with the stuff.


Wintergreen, leaves and berries.


Across the road from the wintergreen we came upon these little guys, Lycopodia.  This is where we discovered the Lycophile among us – Janet.  This is her favorite group of plants, and after finding out why the rest of us have to agree that they are in fact,  very cool.  Fun Lycopodia fact #1, these plants are as ancient as the dinosaurs when they grew into massive trees.  Fun Lycopodia fact #2, early photographers would ignite spores of the Lycopodia plant, which were naturally flammable, to create a flash for their photographs.


Slime mold.
Our last stop was this place, which felt like how we imagine entering an enchanted forest would be.  These mossy hummocks were so cool and so beautiful.



Close-up of a hummock.  There was more of the sphagnum moss, like at the wild cranberry bog, but then also this delicate-looking little vine plant, snowberry.


And in case we ran out of wintergreen tea, we picked up this to make Labrador tea.  This plant was so aromatic it was just in the air, which was downright lovely and contributed to the “enchanted forest” feel of this setting.


Cranberry sauce made from our wild harvest, which was delicious. 


Perusing around the station Annie came across this leaf gall.


Kerry, being a trooper.


Exploring around the station.  While this doesn’t look strange, the ground they are walking on is essentially floating so it feels as if they are walking on a water bed.

Group shot.
We decided if we were a band this is the photo we would use for our album cover, and we would be called “The Oligotrophics.”
Sunset on Lake Tomahawk.
Thanks again, Kyle, for inspiring and spearheading a really educational (and really fun!) weekend.

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.