Seed density in wildflower mixes for pollinators

If you are considering adding wildflowers to your hedgerow (or even your parking strip) new work out of UC Davis suggests that you might not need to add as many seeds as you think to achieve lots of blooms that benefit wild pollinators. Exciting news because it means you can save money while still attracting bees!

The research team planted 3 different densities of a mix of native forbs (herbaceous, annual or perennial plants). They found that the ratio of different plant species to one another had the strongest effects, with one species, gumplant Grindelia camporum, dominating the mixes. Gumplant blooms in the late summer, when most other plants have senesced, making the blooms they provide highly valuable to late season pollinators. For a big early season bloom, the researchers found that chick lupine Lupinus densiflorus provided the highest coverage in their study plots.

Here is a list of the different plant species they used if you want to experiment, but adding more species might increase the overall cost of your planting. Be sure to mix-and-match different bloom periods and life-cycles.


For more detailed information, check out their article from the journal Restoration Ecology:

Wilkerson et al. 2014. Diminishing returns from higher density resotration seedings suggests trade-offs in pollinator seed mixes.

Bees making headlines on the radio!

Melittologist Lawrence Packer was interviewed by Terry Gross on Wednesday’s Fresh Air. He wrote a new book that highlights that conserving diversity in nature and agriculture is key to keeping bees healthy.

Packer‘s new book is called Keeping the Bees: Why All Bees Are at Risk and What We Can Do To Save Them. Read a brief book review and an excerpt.

Then on Science FridayDennis vanEngelsdorp , who has been a pioneer in promoting and studying honey bee health, spoke about new research that shows the threats of neonicotinoid pesticides to insectivorous birds. Previous work has shown that neonics are highly toxic to invertebrates, but this is the first study I am aware of that connects the pesticide to harm in vertebrates.

The dirt on bees

A week ago I gave a talk all about my research on native bee nesting in agricultural landscapes at East Bay Nerd Nite- it was called “the dirt on bees.” You can watch the raw, uncut video in all it’s glory and learn about where bees are nesting and what it might mean for our food security. It’s is available on the Nerd Nite website, my talk starts at 1 hour, 13 minutes, so be sure to cue it up or there is a lot of dead time:

President Obama establishes a task force to develop a “National Pollinator Health Strategy”

Over the weekend the white house issued a presidential memorandum that calls attention to the continuing decline of honey bee and native pollinators and set a new agenda to begin addressing the issues head-on. First the memorandum establishes a task forces comprised of numerous governmental departments and organizations. It then goes on to highlight the objectives of the task force, specifically to 1. create a pollinator research action plan, 2. generate a public education plan, and 3. build public-private partnerships to increase and encourage pollinator-friendly habitat.

Buried within the memorandum is a directive for the EPA to assess the effects pesticides, including neonicotinoids, on bees. Another interesting focus is for member agencies to re-evaluate permit and management of power line right-of-ways, areas that could be managed for pollinator habitat. The Department of Agriculture has been given 90 days to come up with best practices to enhance pollinator habitat on federal lands- something it would be very neat to be involved in (so we could help them focus on nesting habitat).

At the same time, the USDA has pledged $8 million to agricultural conservation reserve programs in the midwest states to establish new habitat for honey bees (habitats which also benefit native bees).

In all, Pollinator Week was a resounding success in terms of actions taken on capital hill. This is the largest national effort at pollinator conservation since the Pollinator Habitat Conservation Act in the 2008 Farmbill. I look forward to the exciting research and conservation efforts spurred by this timely and important legislation.

“Buzz about bees” discussion pannel

Next week is Pollinator Week! 

You can start it off Monday June 16th by going to or live streaming a discussion about bees and their decline, co-sponsored by the Berkeley Food Institute and the Pesticide Action Network:

What’s the buzz about?: A conversation about bee declines, impacts on our food system and what you can do about it

Most of the worlds sunflower is grown in California . . . initially

Sunflower field near Winters, CA

Sunflower field near Winters, CA

Although I study sunflower, even I was surprised to learn that most of the world crop originates in California. The Central Valley is the incubator for seeds that then get shipped around the world and grown into the plants that provide us with sunflower seeds and sunflower oil. Those thousands of acres of buttery yellow blooms create the blooms elsewhere next year!

Learn more about the interesting, global process here:

Help count pollinators this Thursday

Citizen science is a great way to get involved in important projects and provide key data. The University of California is asking you to go outside and count all the pollinators you see for 3 minutes, then add that data to their map. This will help them learn which pollinators people re seeing all over the state.

To learn more about how you can contribute, check out their web page:

Massive honey bee die off in almonds this year

Honey bees that were brought in to pollinate almonds in California experienced steep declines this year- including colony collapse and deformation of young bees. What’s causing the problems? Eric Mussen, a honey bee specialist at UC Davis thinks it could be from a new “cocktail” of pesticides that are not very dangerous to bees when sprayed alone, but highly toxic when mixed together. To learn more about the specifics, see the full article here:

Everything you wanted to know about neonicotinoid pesticides

Neonicotinoids (neonics) are the most commonly used pesticide globally.  They are widespread partly because they are highly toxic to insects without being very toxic to mammals, and can be applied in a variety of ways. They are most commonly applied as a seed coat- when the plant germinates it draws the pesticide into all it’s cells, from leaves to pollen- but can also be applied as a spray.

Using a seed coat pesticide marks a shift away from an integrated pest management approach that uses natural enemies and only uses chemicals when certain thresholds of damage are surpassed, toward application of pesticides before they are needed, in fact, before the crop even germinates.

In a new review in Ecological Applications, Dr. Dave Goulson, outlines the environmental risks of this new class of pesticide that is sweeping agricultural areas throughout the world. He asks whether the evidence shows that neonicotinoids are safe, or whether they have dangerous consequences we should consider.

First, how much economic edge do neonics give farmers over other types of pesticides? Though this is relatively unstudied, Goulson suggests that the little evidence available points to little benefit. In trials of treated and untreated soybeans, there were no differences in crop yields between fields treated with the main neonic on the market, imidacloprid, and those that were not. In winter wheat, a seed coating cost more than the added benefits accrued from lack of pest damage. One study, again on wheat, found that there were benefits of a foliar spray, but none from a seed coating.

Pesticide coated seeds are sown directly into the ground, and evidence is increasingly showing that most of the pesticide doesn’t make it into the plant, but instead accumulates in the soil. Only about 16-20% of the active ingredient is absorbed by the crop. Some (~2%) flies off as dust while seed are being sown. The rest remains in the soil, building over time, or goes into waterways as part of agricultural runoff. The chemical can remain in the soil for between 200-1000 days depending on the soil conditions. Fields in France were randomly sampled for traces of neonicotinoids, and the majority of samples from conventional farms had traces of the chemical, even those that had not been treated for more than 2 years. This could lead to uptake of neonics by non-target plants, including crops and hedgerows.

Neonics have been detected in all kinds of waterways, including rivers, streams, storm-water ponds and tidal creeks. The substance has even been found in groundwater. Neonics may be under-detected because they are not currently part of water monitoring programs. The levels and frequencies of contamination may be higher than currently thought. Again, plants along waterways or irrigated with contaminated water may absorb the pesticide, even when application was not intended.

Having consistent levels of the chemical in the environment can lead to increases in resistance, which could be very damaging if it occurs in pest insects. Resistance has already been recording as occurring in as little as 3 years from introduction of the pesticide- which is heightened in species that have short generation times.



Given that neonics are present in may environments after they are sprayed, the next question Goulson asks is whether this has lingering effects on populations of invertebrates- particularly beneficial insects, such as pollinators. Neonics are commonly used as a seed coat on crops that provide floral resources to bees, particularly oilseed rape and sunflower. They are also used as foliar sprays on fruit crops, such as raspberries. The highest concentrations of the pesticide are found when they are applied through irrigation water. Bees collecting pollen and nectar can be exposed multiple times, which can either lead to death, or other non-lethal complications such as reduction in foraging and homing ability (being able to return to their nest). Bumble bees were found to produce fewer offspring when they foraged on neonic treated crops. Most studies to date have focused on adult bees, but larval bees that consume pollen could also be exposed to low concentrations of the active ingredient, and therefore exhibit similar problems as those seen with mature bees.

According to Goulson, it is apparent that the increasing rate of neonicotinoid application in crop fields is having a negative effect on biodiversity conservation in agricultural landscapes. This means a reduction in expected ecosystem services provided by beneficial insects such as pollinators and natural enemies. Concentrations in the soil may harm essential organisms that paly a role in soil health and fertility. He suggests re-evaluating the current high use of neonics in farming, and considering appropriate reductions that better balance all aspects that go into farming and stewardship.


Goulson, Dave. “Review: An overview of the environmental risks posed by neonicotinoid insecticides.” Journal of Applied Ecology 50.4 (2013): 977-987.