Utah Pest News Summer 2010

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Increasing the Number of Pollinators on the Farm

Osmia ribifloris
Fig. 1. The beautifully iridescent Osmia ribifloris is a bee that you might encounter on a Utah farm.

Growers are well aware of the contribution of bees and other pollinators on the farm.  But how can you increase the number of pollinators on your farm?  Many growers do not have time to manage honey bees, and renting hives has become increasingly expensive.  However, it is possible to attract wild bees, including feral honey bees and native bees, without too much difficulty.

A three-step approach is recommended for increasing pollinator populations on your land.  First, evaluate the bees and bee habitat that already exist on your farm.  Second, adjust your farm management practices to protect bees and their habitat.  Third, provide new bee habitat.  Increasing pollinator populations should be easy to work into your time and financial constraints, and also easy to adapt to your unique situation.

A simple, yet important, first step is to become aware of the pollinators and habitat that are already present on your farm.  As you go about your day’s work, be alert to what bees you see and where you see them.  Remember, not all bees look like honey bees.  Some bees are quite tiny, and others can be quite large.  Many bees are black and yellow, but some are bright green or iridescent bluish-black (Fig. 1).  When you spot bees, observe them.  Do they seem attracted to a particular plant?  Often the flowers that bees find most attractive are the simple, wide-spread native wildflowers, rather than the fancy, highly-bred flowers that people find pleasing.

In addition to noting where bees are foraging, pay attention to where they are nesting.  Wood-nesting solitary bees can be found in beetle tunnels in old trees or in soft-centered twigs, such as raspberry canes.  Ground-nesting solitary bees like undisturbed soil where plants are not growing.  If you see them flying low in a flower-free area, and it looks like they are searching for something, they are probably close to their nest.  Bumble bees also nest in the ground, often in old rodent burrows or under small, protected piles of leaf debris or grass.

The second step is independent of the first step.  Management practices can be adjusted to protect bees even if you have not surveyed for them on your property; however, knowledge of bees’ whereabouts will result in more efficient and productive management adjustments.  One thing that every grower can do is to minimize the risk that pesticides pose to bees.  Scouting for pests and only spraying when pest populations are high will decrease the chance of killing bees, as will choosing “softer” pesticides.  The pesticide label is a useful source of information about risks to bees, but it is important to note that most pesticides are tested for toxicity to honey bees.  As more research is being done, it is apparent that not all bees are affected in the same way as honey bees, and the effects of pesticides on most bees are not known.  Spraying when bees are not active (either very early or very late in the day) can help minimize risk.  Another good practice is to establish buffer zones, areas around the outer edge of the crop that will remain unsprayed.

In addition to pesticide considerations, there are other adjustments that can make management practices more bee-friendly.  Allowing crops to flower before tilling can provide additional forage and extend the reproductive season for some bees.  When you do till, remember that many bees nest in the ground, about 8-18 inches deep (depending on species), sometimes right next to the plants that they pollinate.  If you know that an area contains bee nests, consider tilling less deep or finding an alternative to tilling if possible.

A common mistake is to destroy flowers that might distract pollinators from the target crop.  Actually, having additional flowers available before and after crop bloom can increase bees’ nesting season and increase their populations.  You may also consider leaving weeds that are good food plants for bees.  Of course, noxious weeds must be removed, but think about letting the less troublesome weeds remain for foraging bees.

If you have implemented pollinator-friendly changes in your management practices, and would like to take the final step to enhancing your farm for pollinators, you can actively create bee habitat.  You can start by increasing the amount and variety of blooming plants available for bees.  Using native plants is a good idea, but not a requirement.  Make sure that you consider their bloom periods, so that there are continuous flowers from season to season.  A large assortment of plants is usually recommended, but often growers find that it is easier to manage a few varieties that are particularly suited to their farm conditions.  As long as you are increasing and extending available forage, you are enhancing pollinator populations.

Creating additional pollinator nesting sites can also be easily achieved.  The majority of bees are ground-nesters, which would benefit from patches of undisturbed, loosely packed soil without extensive vegetation.  South-facing slopes are preferable, but any land that is fairly close to forage and is not overly moist will be suitable for nesting bees.  A large proportion of the bee fauna are cavity-nesters that would be well served by large pieces of wood with holes drilled in them.  Drill holes of several different sizes to attract different bee species.  If you have habitat for ground-nesters and habitat for wood-nesters, you have accounted for the majority of the native bees that are likely to take up residence on your farm.

Encouraging more pollinators on the farm does not need to be difficult or time consuming.  Keep it simple, especially in the beginning while you are figuring out what works best for your unique conditions.  Be aware of the pollinators that you already have, take steps to preserve them, and if it is right for you, increase the pollinator habitat that you have available.  The 2008 Farm Bill contains several programs which provide monetary support for growers that implement conservation plans and increase bee habitat.  In a future article, I will discuss how you can take advantage of these programs.

-Cory Vorel, USU CAPS Coordinator

Cane, J., and L. Kervin.  2009, Gardening for Native Bees in Utah and Beyond;    http://extension.usu.edu/files/publications/fact sheet/plants-pollinators09.pdf.
Farming and Gardening for Pollinators; http://www.nbii.gov/portal/server.pt/community/farming_and_gardening_for_pollinators/986.
Vaughn, M., M. Shepherd, C. Kremen, and S. H. Black. 2007,  Farming for Bees: Guidelines for Providing Native Bee Habitat on Farms.
Warner, G.  2009. Cultivating beneficials: An insectary can attract bees and other beneficial insects to the orchard. Good Fruit Grower, 60(17): 54-55.
     Farming for Pollinators: Native Bees and Your Crops.
     Farming with Pollinators: Increasing Profit and Reducing Risk.