Field Experiment II. Alternative Forage Pesticide Mitigation

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Background

For years, commercial beekeepers have been experiencing late summer bee kills and colony decline in the north end of Rabun County, Georgia, USA. Something was killing bees each summer. Corn was suspected. Bee kills and corn are often associated with neonicinoids. However, a previous experiment, Field Experiment I. Environmental Pesticide Concentrations showed that the problem here is not neonicotinoids, but cyhalothrin.

We would like to test whether controlled plantings of alternative forage, timed to bloom when the corn tassels, will reduce the insecticide levels in the hive. The theory is that providing a pollen source with higher protein content will attract bees and keep them off the corn. This is similar to a trap crop, but instead of attracting agricultural pests away from nearby crops, we would be attracting bees away from the crops. If this works, it could be considered a form of companion planting with great potential.

Procedure

  1. Identify pesticide in pollen.
  2. Determine source, timing of bloom, protein content of toxic pollen.
  3. Plant enough higher quality pollen sources in strategic locations to provide adequate pollen to the hives in the area.

Field Observations

  1. Survey number of bees on each corn plot:
    1. first time corn tasseling/pollen production.
    2. once a week twice a day, morning and afternoon.
  2. Trap pollen at the hive and determine quantities of each type coming in.
  3. Test pollen for cyhalothrin

Crop Requirements

Need crops that would meet our requirements of:

  1. a pollen source that honey bees work
  2. with a higher protein content than corn
  3. that can be planted to bloom from about the 3rd week in July through the end of August.
  4. that provides a benefit to the farmer (eg cattle feed),
  5. can be easily planted (maybe with the same equipment used to plant corn),
  6. easily grown without insecticides,
  7. can be planted in established pastures without burndown,

The only crop that we've been able to come up with is buckwheat.

Burndown required to reduce competition

References

The Benefits of Pollen to Honey Bees Amanda Ellis, Jamie Ellis, Michael O'Malley, and Catherine Zettel Nalen http://edis.ifas.ufl.edu/in868

Plant species differ in the quantity and quality of pollen produced. Some plants may produce an abundance of pollen, but the pollen may be of poor quality, whereas others may produce very little but high quality pollen. Plants that are closely related (within the same genus) tend to have similar amounts of crude protein available in their pollens. Plants with relatively high crude protein values include canola (Brassica napus – 23%) and almond (Prunus dulcis – 26%), while plants with lower crude protein levels include raspberry/blackberry (Rubus spp. – 19%), willow (Salix spp. – 17%), sunflower (Helianthus annuus – 16%), and pine (Pinus spp. – 7%). It is important to note that there are several different methods used to analyze protein content in pollen which, in turn, can yield different results. Consequently, one must use published protein levels in various pollens as a general guideline and not a definitive value. It has been observed that honey bee workers choose pollen based on the odor and physical configuration of the pollen grains rather than based on nutritive value. A typical size honey bee colony (approximately 20,000 bees) collects about 57 kg of pollen per year. On average, 15-30% of a colony's foragers are collecting pollen. A single bee can bring back a pollen load that weighs about 35% of the bee's body weight. Bees carry this pollen on their hind legs, on specialized structures commonly called "pollen baskets" or corbicula (Figure 3). Once pollen is brought back to the colony, the workers condition it by adding glandular secretions containing enzymes and acids that prevent harmful bacterial activity and prepare the pollen for long-term storage (Figure 4). Stored pollen often is called "bee bread". Bees also add beneficial microbes to the pollen and they produce enzymes that help the pollen release nutrients and amino acids. Bee bread is consumed by a colony relatively quickly and only stored for a couple of months if there is a surplus. A colony's annual requirement for pollen has been estimated to range from 15 to 55 kg. A good publication to review for pollen contents of many common plants is Fat Bees Skinny Bees – a manual on honey bee nutrition for beekeepers (https://rirdc.infoservices.com.au/downloads/05-054). The authors of this manual include a list of pollen compositions from some common Australian plants. When reviewing the list, remember that plants within the same genus often have similar protein contents. This list can serve as a guideline for predicting protein content of pollen from similar plants in the United States. A worker bee consumes on average 3.4–4.3 mg pollen per day, with a peak at the age of nurses (Crailsheimet al., 1992). Nutrition and health in honey bees Robert Brodschneider, Karl Crailsheim http://www.honeybee.com.au/Library/Pollenindex.html https://u.osu.edu/beelab/files/2014/08/Johnson_Lin_Webinar_081914_handout-1-1z6bl1d.pdf



Rapeseed (Canola)

Plentiful high quality pollen Nectar crystallizes quickly Buckwheat


Lavender Lavandula

Requires hot, dry climate with well drained rocky soil vetch