Posts Tagged: pollination
The study found that wild bees were more abundant in diversified farming systems. Unlike large-scale monoculture agriculture, which typically relies upon pesticides and synthetic fertilizers, diversified farming systems promote ecological interactions that lead to sustainable, productive agriculture. Such systems are characterized by high levels of crop and vegetative diversity in agricultural fields and across farming landscapes.
“The way we manage our farms and agricultural landscapes is important for ensuring production of pollinated-food crops, which provide about one-third of our calories and far higher proportions of critical micronutrients,” said study senior author Claire Kremen, professor at the University of California, Berkeley’s Department of Environmental Science, Policy and Management. “This result provides strong support for the importance of biologically diversified, organic farming systems in ensuring sustainable food systems.”
Many of the study’s authors, including Kremen, also co-authored a study published March 1 in Science that found that fruit and vegetable production increased when wild pollinators – as opposed to domesticated honeybees – were more abundant.
“That study showed that wild bees helped crop yield, and this study shows that organic crops in a diversified farming system help wild bees,” said Kremen.
Christina Kennedy, senior scientist at The Nature Conservancy, is the study’s lead author.
- Wild Bees Are Good for Crops, But Crops Are Bad For Bees (NPR interview)
- Better Bees: Super Bees and Wild Bees (KQED Quest video)
- Wild bees make honey bees better pollinators (UC Berkeley press release)
CCD, the mysterious phenomenon characterized by adult bees abandoning the hive, leaving behind the queen bee, immature brood and stored food, surfaced in the winter of 2006. Scientists believe CCD is caused by multiple factors: diseases, viruses, pesticides, pests, malnutrition and stress.
Meanwhile, misinformation about bees continues to surface. Posts on Facebook, Twitter, Pinterest and other social media often caption a syrphid fly as a bee or a syrphid fly as a bumble bee. Magazine and newspaper editors frequently misidentify a syrhpid fly (aka flower fly and hover fly) as a honey bee. Even the cover of the well-respected book, Bees of the World, by Christopher O’Toole and Anthony Raw shows a fly, not a bee. University of Illinois-based entomologist Alex Wild, who received his doctorate from UC Davis, mentioned the error in his Scientific American blog.
So, we asked noted honey bee authority Eric Mussen, UC Cooperative Extension apiculturist based in the UC Davis Department of Entomology: What should the general public know about honey bees? Can you share some basic information? A honey bee primer?
First of all, honey bees are not native to the United States. European colonists introduced them to what is now the United States in 1622. The site: the Jamestown colony in Virginia. Then in 1853, the honey bees were introduced to California. The site: San Jose.
“Honey bees,” Mussen says, “are commercial pollination workhorses, while native bees — mostly solitary — pollinate the native plants of field and forest. Around 250 commercial California beekeepers operate about 500,000 honey bee colonies, approximately one-fifth of the country’s supply. Over 72 percent of commercial crop pollination is conducted in California, and about one-third of our daily diet is dependent upon bee pollination. We also have about 6,000 small-scale or hobby beekeepers, who tend to keep one to five colonies.”
Mussen attributes CCD with “fomenting great media and public interest. It also sparked an increase in the number of small scale beekeepers.”
About 60,000 individuals, including the queen, thousands of worker bees (sterile females) and drones (male bees) comprise a colony in the late spring/summer.
“Up to a thousand drones are present during the mating season,” Mussen says, “but they get evicted at the end of the fall.”
The drones serve one purpose: to mate with a queen. And then they die. When a virgin queen is about 10 days old, she will mate with 12 to 20 drones on one or more mating flights. The queen returns to the hive and begins laying eggs, as many as 2,000 eggs a day.
“Bees are vegetarians and live on pollen and nectar obtained from flowers or extra-floral nectarines,” Mussen says. “A mix of pollens is required to meet honey bee nutritional needs.”
During the active season, a honey bee colony each day requires an acre-equivalent of blooms in order to meet its nutritional needs. Bees store both pollens and honey for winter food. The bees usually forage within five miles of the hive. Nutrition is crucial to a healthy hive.
“Malnutrition impairs the protective physiological systems — particularly the immune system and detoxification system — and leads to less productive and shorter-lived bees,” Mussen says.
The bottom line: “More research is required to find better ways to reduce populations of honey bee parasites, reduce levels of honey bee diseases, and develop beekeeping management practices that prevent excessive losses of honey bee colonies during the year.”
Honey bee on blanket flower, Gaillardia. (Photo by Kathy Keatley Garvey)
This floral visitor, a syrphid fly, is often mistaken for a honey bee. (Photo by Kathy Keatley Garvey)
Leadership of California’s higher education systems made the funding available to jointly address issues in agriculture, natural resources and human sciences. Project criteria include collaborative research, teaching, or course development; development of student internship opportunities; and workshops, conferences, and symposia. Eight projects totaling more than $79,500 were selected from 30 proposals submitted.
“These research projects will help leverage limited resources to produce quick results on important issues in California,” said Neal Van Alfen, dean of the College of Agricultural and Environmental Sciences at UC Davis. “They are also building stronger connections among researchers throughout the state and providing hands-on learning opportunities for students.”
Researchers involved in this year’s projects are from UC Davis, UC Berkeley and California State University campuses at Chico, Fresno, Humboldt, Pomona, Sonoma, San Marcos and San Luis Obispo. The awarded projects, with principal investigators, are listed below:
- “Estimating residential water demand functions in urban California regions” — Economists from UC Berkeley and Cal Poly San Luis Obispo will estimate residential water demand of municipalities and water companies that serve 19 million people in the Bay Area and Southern California. (Maximilian Auffhammer, Stephen Hamilton)
- “Reintroduced mammals and plant invaders as key drivers of ecosystem processes in coastal and interior grasslands” — Researchers from Sonoma State University and UC Davis will study how reintroducing tule elk and reducing invasive Harding grass affects the availability of soil nutrients and the composition of plant communities. (Caroline Christian, J. Hall Cushman, Valerie Eviner)
- “Genetics of plant defense responses to pesticides and spider mites on grapes” — Scientists from UC Davis and Cal Poly San Luis Obispo will conduct laboratory, greenhouse and field studies to learn more about factors affecting grapevine response to spider mites, including cultivar resistance, drought impact and pesticide exposure. (Michael Costello, Richard Karban, Andrew Walker, Jeffrey Wong)
- “Defining the functions of polyphenol oxidase in walnut” — Through genetic analysis, researchers at CSU San Marcos and UC Davis seek to learn more about an enzyme involved in the postharvest browning of cut or bruised fruit. (Matthew Escobar, Monica Britton, Abhaya Dandekar)
- “Modeling the costs of hazardous fuel reduction thinning treatments and removal of woody biomass for energy” — Researchers from Humboldt State University, UC Davis, and the U.S. Forest Service will develop a model to estimate the costs of removing hazardous wildland fuels with different equipment and systems over a wide range of forest stand, site and road conditions. (Han-Sup Han, Bruce Hartsough)
- “Restoration of pollinator communities and pollination function in riparian habitats” — Researchers from California State University, Chico, and UC Davis will characterize native pollinator communities at restored riparian habitats within the Central Valley and test whether successful restoration of pollinator communities also leads to restoration of pollination. (Christopher Ivey, Neal Williams)
- “Estimating alfalfa’s impact on regional nitrogen budgets and nitrate leaching losses in the Central Valley of California” — Researchers from California State University, Fresno, and UC Davis will collect alfalfa and non-legume plants from irrigated fields and also identify San Joaquin Valley farm sites for a multi-year study of alfalfa’s impact on regional nitrogen budgets, groundwater nitrate leaching, and nitrogen requirements of rotation crops. (Bruce Roberts, Stuart Pettygrove, Daniel Putnam)
- “Community and ecosystem response to elevated nitrogen in managed grassland ecosystems” — Restoration ecologists from Cal Poly Pomona and UC Berkeley will investigate how elevated nitrogen levels affect competition among native and exotic plant species with regard to fuel characteristics at UC’s South Coast Research and Extension Center. (Erin Questad, Katharine Suding)
Reports on project outcomes are expected in December 2012.
Whether you’re trying to garden at home more sustainably (minimizing water use or using pollinators), or whether you want the most up-to-date information on beautiful new plants, new gardening practices, or new hardiness zones, I have assembled some practical information for home gardeners.
The horticultural staff of the UC Davis Arboretum have identified 100 tough, reliable plants for California that are easy to grow, don’t need a lot of water, have few problems with pests or diseases, and have outstanding qualities in the garden. Many of them are California native plants and support native birds and insects. Most All-Star plants can be successfully planted and grown throughout California. The Arboretum All-Star website not only provides cultural information on each of the plants, but also has a searchable database, photographs, and an audio slideshow.
For those of you outside of California, if you have a similar climate (see the section below on hardiness maps), these All-Stars may grow well for you, too.
Arboretum plant sales
The UC Davis Arboretum and the California Center for Urban Horticulture are working with wholesale and retail nurseries in California to make sure that the All-Star plants are available for home gardeners. Check with your local retail nursery to see if they carry All-Stars, check the online list, or go to one of the Arboretum’s plant sales if you are in Northern California. These plant sales draw gardeners from all over Northern California who want unique, specialty, or All-Star plants that perform well in California: plant sale dates.
If you want to create a pollinator paradise in your landscape, you might want to attend the Pollinator Gardening workshop at UC Davis on April 28, 2012. Sponsored by the California Center for Urban Horticulture at UC Davis, this full-day workshop will have entomologists, horticulturalists, and design experts present to inspire gardeners and equip you with the tools to provision pollinating insects in your own landscape. Learn what you can do to support healthy bee communities.
Roses, roses, roses
Rosarians and garden amateurs will all enjoy the annual Rose Day workshop at UC Davis on May 5, 2012. Sponsored by the California Center for Urban Horticulture, the program features rose-breeding experts Dr. James Sproul and Jacques Ferare, rose tours on the UC Davis campus, and a rose plant sale.
The New Sunset Western Garden Book
The ninth edition of the legendary garden book, The New Sunset Western Garden Book, was recently released, and features over 2,000 color photographs (goodbye, little hand sketches!), a complete redesign, an encyclopedia of 9,000 plants, and a “plant finder” section.
New plant hardiness maps
The U.S. Department of Agriculture recently released a new version of its Plant Hardiness Zone Map, updating a useful tool for gardeners and researchers for the first time since 1990 with greater accuracy and detail. The new map is available online. The map offers a Geographic Information System (GIS)-based interactive format and is specifically designed to be Internet-friendly. The map website also incorporates a "find your zone by ZIP code" function.
While the map is useful in many areas of the U.S., some gardeners in California find it not specific enough for our multitude of microclimates (Mediterranean, maritime, mountainous, and more), so many California gardeners still rely on Sunset’s climate zones.
A lack of pollination by honey bees — brought on by increased insecticide use to control onion thrips — was linked to a sharp decrease in yields of California onion seeds, according to research published in the July-September 2011 issue of the University of California’s California Agriculture journal.
“Honey bee visits to onion flowers were negatively correlated with the number of insecticides applied per field and field size,” wrote the study’s authors, Rachael F. Long of UC Cooperative Extension in Yolo County and Lora Morandin of the Department of Environmental Science, Policy and Management at UC Berkeley. “Reduced onion seed yields in recent years could be associated with the increase in insecticide use, which may be repelling or killing honey bees, important pollinators of this crop.”
The research was conducted in May and June 2009, in 13 commercial hybrid onion seed production fields in Yolo and Sacramento counties. At each of six sampling sites per field, the researchers observed the numbers and types of insects visiting onion flowers that were potential pollinators of onions. To assess onion seed yields relative to insect pollinator activity, they collected onion umbels from the sampling sites and counted the seeds to obtain average yield data. Ground mapping was done around each field to determine whether other preferred floral resources were available to honey bees, perhaps luring them away from onion flowers.
Onion thrips were previously of minor importance in onion seed production. However, iris yellow spot virus is a new pathogen for California onions that is vectored by onion thrips, and it can cause significant onion seed yield losses if left unmanaged. The insecticides used by growers at these field sites to control onion thrips included spinosad, spinetoram, methomyl, cypermethrin, lambda-cyhalothrin and sodium tetraborohydrate decahydrate. The number of insecticides applied per field ranged from one to seven, including tank mixes, with all pesticides applied prebloom. The number of bee hives per acre ranged from four to 14, with the exception of one field that had resident hives at 42 per acre.
“This study found that the number of insecticides applied and field size were the strongest predictors of honey bee activity and onion seed yields,” the authors wrote.
Long and Morandin cautioned that to confirm a causal relationship, more information is needed on the specific effects of different classes and rates of insecticides on honey bee activity. In addition, cultivar can play a role in honey bee activity and needs to be further investigated with respect to pesticide use and bee activity.
“Our study suggests that growers should exercise caution when using insecticides, applying them only when needed as opposed to preemptively, to better protect both wild and honey bee pollinators,” the authors wrote. “Also, the negative correlation between field size and honey bee activity suggests that spreading honey bee colonies around onion fields rather than grouping them may increase honey bee activity and pollination in larger fields.”
Onion seed is primarily grown in Colusa County and the Imperial Valley on about 2,000 acres. The value of the seeds is $12 million to growers, according to agricultural commissioner county crop reports, and they generate an additional $40 million in subsequent retail sales.
“While clearly a specialty, small-acreage crop, onion seed production is important to the rural economies in California where onion seed is primarily grown,” Long and Morandin noted.
Rachael Long monitors pollinator activity in a hybrid onion seed field. Honey bee hives (foreground) are placed in fields to promote pollination. (Photo: Edwin Reidel)