Gratton lab member Kaitlin was recently invited by American Scientist to write a brief response to the federal strategy to protect pollinators put forth by the interagency Pollinator Health Task Force in May of this year. In a post for their Macroscope column, she discusses what she sees as the pros and cons of the plan. She also briefly reviews how pesticides are approved and banned under US law. Kaitlin worked as a staff scientist for the US Environmental Protection Agency Office of Pesticide Programs, in the Biological Analysis Division and with their Pollinator Protection Team, before joining the Gratton lab.
Post by Christina Locke and Claudio Gratton
We are often asked about neonicotinoid pesticides, or “neonics”, and their effects on bees. Neonics are the most widely used insecticides globally, and are in the news a lot these days due to concerns about their effects on birds, fish and beneficial insects including pollinators. Some countries, states and municipalities have moved to limit their use because of these concerns.
Neonics became commercially available in the 1990s and quickly became popular for their high toxicity to insects and relatively low toxicity to vertebrates. Neonics are water soluble, systemic insecticides, which means they can be taken up by a plant’s roots and spread to the whole plant, including its pollen and nectar. Unlike other classes of pesticides like pyrethroids that are acutely toxic to insects but break down quickly in the environment, neonics persist in plants, soil and water for long periods of time–weeks to months, and even longer in soil and woody vegetation. Besides concerns about acute toxicity of adult bees, there are serious concerns of chronic sub-lethal effects (like confusion) that affect bee behavior and colony health over time. Many laboratory studies have shown detrimental effects of neonics on bee feeding, learning and memory. Four of the five most common neonics are considered highly toxic to bees when bees are exposed directly to the chemical or its residues. However, field studies have been less conclusive and most show little effect of neonics on honeybees. This doesn’t mean that neonics are off the hook. A well designed study recently published in Nature shows significant adverse effects of neonic seed treatments on wild bees. Bumblebee colony growth and reproduction, as well as solitary bee nesting, were reduced in fields treated with neonics while effects on honeybees were not detected. Exposure to neonics is especially of concern in mass-flowering crops like canola that are very attractive to pollinators. In cities, too, inappropriate neonic use on highly attractive flowering trees can lead to massive bee kills.
U.S. EPA action on neonics
The U.S. Environmental Protection Agency (EPA) has taken several steps in the past several years regarding neonics and honeybee testing:
Change in pesticide risk assessment protocol to a tiered system that tests pesticide effects on multiple honeybee life stages and colony-level effects. Old testing methods focused only on adult bees.
Review of neonicotinoids began in 2008 and is scheduled for completion in 2016 for most neonics.
No new registered uses will be allowed for neonics until new risk assessments are complete.
New labeling requirements for pesticides known to be toxic to honeybees (see photo at right).
Proposed prohibition of neonic use on flowering crops where contracted pollinators (usually managed honeybees) are present. This restriction is currently undergoing public review through June 29–go to regulations.gov to submit a comment on docket “Mitigation for Pesticide Products that are Acutely Toxic to Bees.”
Investigating bee kills tied to specific pesticides through a voluntary bee kill reporting system (anyone can report a bee kill).
Guidelines to assist states and tribes developing their own pollinator protection plans. Federal funding may also become available to support plan development.
Of course, there are limitations of these actions. The EPA pesticide risk assessments test effects on honeybees only, not other pollinators like wild bees and butterflies, and not insects that eat crop pests like lady beetles. Though neonics are more toxic to insects than other organisms, they can and do affect vertebrates. In birds, direct ingestion of neonic-treated seed is associated with decreased egg size, lower fertilization rates and death. There is room to expand the dialogue on neonic seed treatments, the use of which is widespread, and at least in soybeans has no clear yield benefit. Even as movements are taken on neonics, new systemic pesticides like flupyradifurone are being approved, and although they are purported to be less detrimental to bees than neonics, they have not yet undergone as much scientific scrutiny. Still, protections designed for honeybees are expected to benefit other beneficial insects, and steps taken thus far by EPA can be considered steps in the right direction for pollinator protection.
It’s more than just pesticides
Bee declines are the ultimate effect of many combined insults, and a multi-faceted approach is necessary to ensure pollinator health into the future. Honeybees and wild bees are both affected by habitat loss, and may face nutritional deficiencies when areas of highly diverse flowering plants, like prairies, are replaced by large crop fields where only one type of plant blooms at a time. Furthermore, social bees are hit by a variety of colony pests and pathogens that compromise their immune systems. Diseases, parasites, pesticides, habitat loss, and poor nutrition act together to hit pollinator communities hard. The newly released White House Strategy outlines national efforts to increase pollinator habitat, address beekeeping concerns, and reconsider the widespread use of neonics. Though some will argue that these measures do not go far enough towards pollinator conservation, it is truly remarkable to see pollinator issues on the national agenda and part of everyday dialogues in agency settings and public arenas.
Postdoc Christina and graduate student Kiley were guests on The Perpetual Notion Machine, a science radio show, on 89.9 WORT FM, a public community radio station here in Madison, WI on May 7th. They discussed their research, the ongoing work on the state pollinator plan, and how Madisonians and Wisconsites all over can get involved with citizen science and backyard efforts to help wild and managed insect pollinators.
You can download or stream the show here. Check it out!
Gratton lab member Rachel Mallinger has created an online WI Wild Bee Guide for native bee species commonly found in the spring and early summer. The guide allows users to identify bee species using picture matching or a dichotomous key.
The guide’s purpose is two-fold: allow people to identify bees themselves and act as a citizen-science tool to collect more data about bee abundance and distribution statewide. At the end of a successful bee identification, the site prompts you to fill out a quick form where you can submit your identification and the time and place you saw the bee.
The guide’s easy-to-use format is aimed for everyone from farmers to gardeners to students to curious citizens. With over 500 species of bees in the state, the guide helps users narrow in on the bee family or genus, if not to species.
Landowners and farmers may be able to use the identification tool to understand what kind of bees are abundant on their land and use that information to plant nectar and pollen resources and manage habitat in a way beneficial to bees.
We have had some extreme weather in Wisconsin this spring. Throughout the Northeast and Midwest, an unusually long warm spell propelled us into spring in early-mid March. While many of us were hoping that the warm weather would last, we were not so fortunate. Multiple nights of hard frost and daytime temps barely and rarely hitting 60 characterized the month of April. People have been asking us, “What are the effects of this crazy weather for insects and for crops?” I have been out doing field work throughout the past month, visiting apple orchards in southern Wisconsin where I study wild bees, and I have observed the potential effects of the weather on pollinators and pollination. Two phenomena related to the weather have occurred this spring, both potentially reducing this season’s fruit crop. In a typical year, fruit trees don’t bloom till late April or early May, after the risk of frost has largely passed. This year, however, with warm temperatures, fruit trees bloomed in early April. Frost then hit many orchards when some trees were in full bloom. While flower buds can better withstand freezing temperatures before they are fully open, hard frost during bloom will destroy the flower and prevent fruit formation. For the late bloomers that escaped the frost, their reproductive success may not be much improved. Cool weather during bloom means fewer bees active and flying, as bees don’t like high winds or low temperatures. Without bees to pollinate, fruit will not set on these trees either. Compared to 2010 and 2011, I have seen dramatically fewer bees visiting blossoms and in my trap samples. However, all a farmer really needs is one, warm day during bloom to ensure a decent crop. And, some of the hardier bees, like bumble bees, will fly in 50 degree temps. So, while it is still too early to give up hope on an abundant tree fruit crop, I predict that yields will be lower this year due to frost and poor pollination weather.
Posted by Rachel Mallinger