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Bats in the belfry? No, bats in walnut orchards

A pallid bat catching dinner mid air. (Photo: Bat Conservation International)
Bats are voracious predators of night-flying insects that target California crops. Research statistics show that a pregnant or nursing female can consume as much as two-thirds of her body weight in insects per night. That's somewhat like a 150-pound man eating 100 pounds of food per day.

What's the economic value of bats to the agricultural pest control? It probably exceeds $23 billion per year, according to recent studies. However, very little data exists on the benefits of bats for individual crops, such as walnuts.

UC Agriculture and Natural Resources researchers, together with UC Davis, are launching a survey to better understand the value of bats (and birds) on managed lands. The voluntary survey, focused on growers and landowners in California's Central Valley, may be completed online.

Work is already underway to assess the pest-control impact of bats on walnut production in the Central Valley with a grant from the U.S. Environmental Protection Agency STAR (Science to Achieve Results).

California produces almost all of the nation's walnuts. Farmers grow some 500,000 tons of walnuts on 290,000 acres, with the annual crop valued at $1.8 billion. Due to popular demand, new orchards are planted every year, calling for more intensive farming practices to manage costly crop pests. For walnuts, the key pest is the codling moth, a larva that feeds on developing nuts. The adult moths begin to fly and lay eggs on the nutlets in May and produce up to four generations per year.

Rachael Long with a bat detector under the Davis causeway. (Photo: California Farm Bureau)
Growers, as part of their pest control management practices, typically use insecticides, spraying once or twice a year for this pest. Many also use pheromones, a mating-disruption technology that prevents males from finding females. Although generally effective, pesticides are expensive and they can have harmful impacts on the environment.

Bats forage in walnut orchards for codling moths and other insects. Colonies of bats double their activity on farms when they roost in bat houses attached to barns in the orchards. The Mexican free-tailed bat is the most abundant species, followed by the Yuma and California myotis, and five other species, including the pallid bat.

In an effort to quantify the economic impact of bats' consumption of codling moths, we captured 36 Mexican free-tailed bats over a three-night period in an 80-acre walnut orchard in Yolo County. Some 3,000 bats live in the bat houses in an abandoned shop on the property.

The research procedure: We opened our mist net from 11 p.m. to 2 a.m. to correspond with codling moth flights and bat activity, and captured the bats as they returned to the roost after feeding. We placed the bats individually in sterile cloth sacks and kept them there until they defecated, then we released them. We quickly froze the guano pellets and shipped them to a USDA lab, where scientists genetically tested them for the presence of codling moths.

Our preliminary data suggest that 5 percent of these bats – about 150 bats from this colony of 3,000 – consumed at least one codling moth per night. We calculated 30 nights per generation for the codling moth, and four generations per year, with each female moth laying 60 viable eggs on individual nuts.

Bats help protect California walnuts from coddling moth.
For a typical 80-acre walnut orchard producing a total of 136 tons of walnuts per year, we estimate that bats can protect about 6 percent of the crop yield, or $29,700 worth of walnuts per season at the current price of $1.65 per pound. That's an economic value of $10 per bat per year. And that figure probably underestimates the true value, since for some species of bats, up to 40 percent of their diet can consist of moths – an average of about 15 moths per night.

The next steps: we are refining our economic data and determining whether these insect-hunting bats help reduce pesticide use in walnut orchards.

Bats provide these pest control services for free while farmers enjoy a decrease of pests in their orchards and an increase in profits.

Co-authors: Rachael Long, UC ANR advisor; and Katherine Ingram, Department of Wildlife, Fish and Conservation Biology, UC Davis.

Posted on Wednesday, April 15, 2015 at 8:22 AM
Tags: bats (4), Rachael Long (4), walnuts (1)

Becoming a fire-adapted community

A fire-adapted community is a community that can survive a wildfire with little or no assistance from firefighters.
Between January 1 and March 15 of this year, 374 wildfires have burned 3,240 acres in California. According to CALFire, the five-year average for the same time period is 359 wildfires burning 1,124 acres. All of this during California's supposed wet winter months. As the East Coast bundles up and digs out from yet another storm, we in California have been shedding layers and applying sunscreen. Though we appreciate lower than normal seasonal disorder blues, we are facing a tough year ahead in terms of potential fire activity. The forest and shrub ecosystems are dry and with little relief in sight, many who live and recreate in the in these areas and their surrounding communities, are crossing their fingers that wildfire will not disrupt their lives this year.

The magnitude of wildfires especially affects those communities that are part of the wildland-urban interface (WUI). Many communities, whose back doors open out into conifer forests, shrub fields or grasslands, have been working towards becoming more resilient and proactive about wildfire. One way is to become a Fire-Adapted Community. A Fire-Adapted Community is a community that can survive a wildfire with little or no assistance from firefighters. The community acknowledges and takes responsibility for this by preparing for a fire at multiple levels including the use of appropriate building construction materials, and proper vegetation management. Members of the community are concerned with safety: safety of the individual, homes and businesses, community infrastructure, open spaces, riparian areas, any and all community assets. They address issues, plan, prepare and work with their local government agencies, fire services and citizenry to reduce their risk if a wildfire comes their way.

There are four elements to a Fire-Adapted Community:

  1. Community collaboration - Strong fire-adapted communities have a role for everyone. This means that all members of the community (government, schools, businesses, homeowners, renters, fire services, emergency responders, etc.) work together to raise awareness of fire risks and increase knowledge of fire ecology and mitigation actions. This is done through various outreach activities, partnerships and incentives. It also includes completing a Community Wildfire Protection Plan (CWPP) that will assess your community's risk and identify actions to take to lower those risks. It could also involve participating in the Ready Set Go! program which is a collaboration between residents and local fire departments to help people prepare (Ready), understand the threats (Set) and evacuate early (Go) in a fire event.

  2. Surrounding environment – Fire adapted communities look beyond their fences to see what risks exist and what actions can be taken in the surrounding landscape to reduce those risks. These actions can include fuels reduction projects, improving community ingress and egress and/or the protection and enhancement of riparian and wildlife habitat.

  3. Planning and regulatory considerations - Fire adapted communities work with their local and state government agencies to ensure that policies, standards and regulations support actions that reduce the risks of wildfire in the community. This may include building codes and standards that encourage the use of non-combustible materials in home construction; the creation of community protection zones that would create a safe environment in the case of resident evacuation; maintaining large turnaround areas for large pieces of equipment; and having a reliable and easily accessible water system.

  4. Neighborhood, landscapes and buildings - All members of a fire-adapted community work to ensure that their homes, businesses and community assets are prepared in the event of a wildfire. This means reducing flammable materials around homes and businesses; maintaining the immediate landscape and using appropriate, less combustible building and landscaping materials; creating fuel buffers around the community; ensuring that streets and homes are well signed; creating safety zones for residents and animals; having a communication plan – who to call and how to connect if a fire occurs; and designating evacuation routes.

All of these actions taken together, in a collaborative process, help build a strong fire adapted community that is better prepared to face and survive a wildfire.


In the Sierra Nevadas, Incline Village, Nev., is an example of a fire-adapted community. For the past 10 years, they have implemented fuels reduction projects based on their CWPP and involved homeowners and local businesses in planning and implementing mitigation actions. Recently, their goal was to engage a larger audience, build personal connections and recruit new volunteers. Their efforts led to a large gathering where participant input was an essential part of community building and the creation of next steps for the fire adapted community leadership. One participant said that it Gave me hope that a coordinated, cohesive strategy to prepare our community is seriously underway.”

“I really admire the many active citizens in communities throughout the Sierra Nevada working to reduce wildfire hazards in their neighborhoods," said Susie Kocher, UC Agriculture and Natural Resources forestry and natural resources advisor. "It really will take all of us working together to help our communities become adapted to wildfire.”

Becoming a fire adapted community also means joining a network of people and projects. The Fire Adapted Communities Learning Network is a repository of information and encourages the development and sharing of ideas that can help your community build capacity, raise awareness and take actions towards wildfire resiliency.

For more information on becoming a fire adapted community, or other items mentioned in this blog, please visit:

 Images courtesy of the National Fire Protection Association.

Posted on Friday, April 10, 2015 at 4:26 PM

Bedbug eradication requires tenant cooperation

Bedbugs go back to their hiding places after eating a blood meal. (Photo: Wikimedia Commons)
To successfully eliminate bedbugs, pest management professionals say they need the cooperation of people living the pests, according to a survey conducted by UC Agriculture and Natural Resources scientists.

California's pest management pros are divided over whether they believe that some of the state's bedbug populations are resistant to insecticides, but they agree that the bugs may survive treatments by finding safe harbor in excessive clutter and personal items that tenants didn't want treated or thrown away. In addition, some settings – such as hotels, motels, college dorms and homeless shelters – may be continually reinfested.

Bedbugs are among the most challenging and expensive pests to manage. Because they are so difficult to eradicate, the job is typically left in the hands of pest management professionals, who face an increasing number of bedbug infestations in California.

UC ANR scientists are working closely with pest management professionals in the state to find ways that will make bedbug eradication easier and more likely to succeed.

Bedbugs co-evolved with humans, and feed exclusively on blood. Their preferred habitat is inside warm rooms near where humans sleep and rest. Bedbugs are drawn to the carbon dioxide that humans exhale with every breath, and they seek out a blood meal by piercing the skin of a sleeping person. A few minutes later, they scurry back to hiding places.

According to an often-referenced annual report conducted nationwide by Orkin Pest Control, the San Francisco Bay Area is No. 14 on the list of 50 cities with the most calls for help controlling the pest. Sacramento-Stockton-Modesto, now at 27, jumped 14 spaces from 2013 to 2014. Los Angeles is fourth on the list, the highest of any area in California. A Terminix report said bedbug calls in Sacramento increased 54 percent from 2012 to 2013, more than any other city in the nation.

“Increases in bedbug infestations may be partly due to changes in the way we manage household pests,” said Andrew Sutherland, the urban integrated pest management advisor for UC ANR in the Bay Area. “In the 1930s and 40s, DDT was commonly used indoors. The pesticide is very persistent and effective and controlled all indoor pests, including bedbugs, sometimes for years.”

Bedbug bites cause swellings that become red and irritated when scratched. (Photo: Chet K. Fukushima)
In the 1980s and 90s, other broad-spectrum insecticides, such as chlorpyrifos and diazinon, were commonly sprayed, but they are no longer approved for indoor use. Today, safer methods, such as baits and traps, are used to control common pests (such as ants and cockroaches), and bedbugs are usually unaffected.

When Sutherland was hired three years ago, he realized there was little information available about obstacles to bedbug control in California.

“Most of the information about bedbugs is from research taking place in the Midwest and the Eastern Seaboard,” he said.

UC ANR awarded funds to Sutherland and Dong-Hwan Choe, a UC ANR urban pest specialist based at UC Riverside, to collect data from those who were on the frontline in the battle against bedbugs – pest management professionals and managers of multi-unit housing facilities. The researchers later received funds from the USDA's Western IPM Center to expand the study to 13 western states.

Early results of Sutherland and Choe's surveys showed that 75 percent of pest management professionals said bedbug infestations in 2014 had increased from the previous year. Forty percent said they believed they have encountered bedbugs that were resistant to insecticides, while 60 percent said they had not.

“There was no correlation between the amount of experience the professionals had and their perception about bedbug resistance in California,” Sutherland said.

The most common way for professionals to become aware of bedbug infestation has been visual inspections after complaints by tenants. Now, prevention is on the rise, an important component of integrated pest management.

“Our objective is to manage pests below unacceptable levels with minimal negative impacts on communities and the environment,” Sutherland said. “Prevention comes before all other management practices.”

The survey found that pitfall traps (interceptors) are used at least sometimes by 40 percent of pest management respondents to monitor for the pests. Active monitors, glue board monitors and harborage or shelter monitors are also employed.

The pest management professionals reported using a wide variety of treatments against bedbugs. Insecticides were most common, used by 91 percent of respondents most of the time. Desiccants, encasements and heat were used most of the time by about half of respondents.

Housing managers had similar responses to the survey questions. Bedbug control is challenging, they reported, when tenants don't report infestations, are not willing or able to prepare their living space for treatment, when tenants bring secondhand furniture into their units, and when they fail to take information about the pest seriously.

One housing manager respondent complained about an “almost total inability to prevent infestation, or to prove its source and (having to shoulder) almost total responsibility for all concomitant costs.”

For detailed information on bedbug life cycle, detection and treatment, see the UC IPM Pest Note on bedbugs.

An initiative to manage endemic and invasive pests and diseases is part of UC Agriculture and Natural Resources Strategic Vision 2025.

Posted on Monday, April 6, 2015 at 11:24 AM
Tags: Andrew Sutherland (2), bedbugs (1)

Take a short jaunt in Mariposa to see a treasure of California native plants

A path along Mariposa Creek where UC ANR Master Gardeners have planted native species.
A half-block from the highway that brings thousands of tourists to Yosemite National Park each year, the UC Agriculture and Natural Resources (UC ANR) Master Gardeners landscaped a short and scenic hiking path that provides the perfect break on a long drive.

The quarter-mile-long Mariposa Creek Parkway runs parallel to State Route 140 (Main Street in downtown Mariposa) on Stroming Road between Eighth and Sixth streets. Along the path, the Master Gardeners created the California Native Plant Demonstration Garden, which includes dozens of beautiful, drought-tolerant plants labeled for easy identification.

The path, which follows a short stretch of Mariposa Creek, was designed to increase appreciation for native flora and encourage Californians to consider “going native” in their own landscapes, said Kris Randal, coordinator of the Master Gardener program for UC ANR Cooperative Extension in Mariposa and Merced counties. Water shortages associated with the ongoing California drought are also driving interest in landscaping with native plants.

“Many natives are drought-tolerant, adapted to local soils, and rarely need fertilizers or pesticide treatments,” Randal said. “With some care and irrigation to get them started, they create a beautiful natural setting that brings pollinators and wildlife into your backyard.”

Randal was an advocate for native plants even before joining UC ANR. As a community educator for the Resource Conservation District in Mariposa County, she coordinated the transformation of a weedy parking lot around the district's building on the Mariposa Fairgrounds into a beautiful display of plants and wildflowers that occur naturally in the surroundings.

UC ANR Master Gardener coordinator Kris Randal with the welcome sign on the Mariposa Creek Parkway.
She did the same thing in her own Mariposa yard, bringing in and nursing the plants that flourish in natural areas.

“After I planted native brush and wildflowers, it was a joy for me to watch diversity come into my yard. Plant it, and they will come,” Randal said.

Randal suggests growing California native plants, even over native plants from other parts of the world with Mediterranean climates – such as Australia, Chile and South Africa – which also are often recommended because of their low water needs.

The California natives, she said, support local wildlife and pollinators, have historical and cultural importance, and save time and expense while adding beauty and ecological health to the environment. Native plants attract native bees, butterflies and hummingbirds and provide seeds, nuts and fruits for other native birds and wildlife. Native plants promote soil health by supporting flora and fauna that flourish underground.

“There's all kinds of magic going on under the soil,” Randal said.

As a first step toward converting to native landscaping, Randal suggests finding a natural area close to home and visiting it every few weeks to see what is growing, and what is blooming. Take notes and consult a plant guide or the Internet to identify the plants.

“It sounds like a lot of work, but it's not,” Randal said. “It's fun.”

This task is particularly convenient for Mariposa County residents, where the UC ANR Master Gardeners planted a wide array of beautiful native plants in one place.

Bush lupin casts a shadow on a bolder along the Mariposa Creek Parkway.
Under the auspices of UC ANR Cooperative Extension, Master Gardeners are trained by UC ANR academics in research-based and sustainable gardening and landscaping practices. They become volunteer educators for non-commercial gardeners. In Mariposa County, a significant amount of volunteer time goes into tending the native plant garden.

In early spring, one of the first deciduous shrubs to leaf-out on the pathway is California buckeye. The leathery, pear-shaped fruits contain seeds that are easily sprouted, or they can be used in dried flower arrangements.

Along the trail, visitors will find California fuchsia, known by many as a natural hummingbird feeder. Blue elderberry, columbine and manzanita also attract hummingbirds to the demonstration garden.

Randal points out soap root, which looks like a grouping of long spindly leaves growing from the ground. Native Americans used pulp from the bulb to make a soapy lather, and they used the fibrous and hairy husks of the bulb to make small brushes to whisk out acorn shell debris from grinding holes.

One of Randal's favorite natives, she said, is a low creeping sage. The fragrant plant forms a low mat as big as 10 feet across with blue-violet flowers May to June. “This is great in a pine forest where it will get afternoon shade,” Randal said.

A lovely shrub known as Ceanothus blue jeans produces profuse powder-blue clustered flowers. The tall evergreen provides a colorful show of flowers with no care or irrigation. Western redbud explodes with magenta blossoms in the spring. Native Americans used the branches for basket weaving and made a red dye from the bark. Red Twig dogwood produces beautiful white blooms in early summer, and its bright red branches are a unique display in the winter.

“Growing native plants help you appreciate your surroundings and feel more connected to the natural world,” Randal said. “It attracts more life and that's why many of us garden.”

An initiative to maintain and enhance healthy families and communities is part of the UC Division of Agriculture and Natural Resources Strategic Vision 2025.

Author: Jeannette Warnert

Posted on Tuesday, March 31, 2015 at 8:44 AM
Tags: Kris Randal (1), Mariposa (1), native plants (1)

Extension conference to help practitioners reach winegrape farmers

Heard it through the grapevine? Extension training ensures information accuracy.
A support network for California winegrape growers will gather in Lodi March 24-26 at the National Viticulture and Enology Extension Leadership Conference. UC Agriculture and Natural Resources plays a vital role in developing and extending research-based information to the California winegrape industry. UC ANR advisors and specialists work directly with farmers and with industry professionals who also help ensure that the latest knowledge on grapevine pest control, nutrition, pruning, irrigation and other practices make their way into the hands of the people growing grapes in the field.

The conference begins on March 24 with presentations on new research. On March 25, participants take a tour of Lodi-area vineyards and wineries. The “Innovations in Extension Symposium” will be March 26. (Full agenda.)

“At the symposium, we'll be focusing on extension strategy,” said Matthew Hoffman of the Lodi Winegrape Commission, the sponsoring organization.

The events involve nearly a dozen UC ANR academics, including three Cooperative Extension viticulture advisors who were hired during the past year: Lindsay Jordan of Madera, Merced and Mariposa counties, George Zhuang of Fresno County and Ashraf El-Kereamy of Kern County.

During the session on innovations in extension, UC ANR's Franz Niederholzer, an orchard systems advisor in Sutter and Yuba counties, will discuss an extension project underway in collaboration with scientists in Washington and Oregon. The project, funded by the USDA, will offer training in spray application technology to the farming community.

“Spray application technology is very important to integrated pest management and to farming in general,” Niederholzer said. “Mischief can happen if you don't spray properly. Growers have so many things to consider, we want to revisit the fundamentals of spraying with them.”

UC ANR specialist Mark Lubell will discuss the use of social networks in agricultural extension. Social networks and social media can help improve access to information, transmit knowledge efficiently and deliver information when and where it is needed. Lubell will share tools that can be used to conduct networked outreach and build extension efforts.

Other UC ANR presenters are Chris Greer, vice provost of Cooperative Extension, Matthew Fidelibus, viticulture specialist based at the UC Kearney Agricultural Research and Extension Center, Ryan Murphy of the Agricultural Sustainability Institute, and Neil McRoberts, plant pathology professor at UC Davis.

For more information about National Viticulture and Enology Extension Leadership Conference, contact Matthew Hoffman at (209) 367-4727,

An initiative to enhance competitive and sustainable food systems is part of UC Agriculture and Natural Resources Strategic Vision 2025.

Posted on Monday, March 23, 2015 at 11:18 AM
Tags: winegrapes (2)

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