Want to learn more about arthropods in rice and alfalfa fields and the UC Davis research underway to help the agriculturists?

Cooperative Extension agricultural specialist Ian Grettenberger, assistant professor, UC Davis Department of Entomology and Nematology, and his graduate student, Madison "Madi" Hendrick, will discuss the crops, the pests, and the natural enemies or beneficials at a virtual Facebook live session from 11 a.m. to noon, Thursday, Oct 22.

The event, "The Good and the Bad: Insects and Other Arthropods in Agriculture, with a Focus on California Rice and Alfalfa," will be live-streamed on the UC Davis Bohart Museum of Entomology's Facebook page. (Link to Facebook live here). Grettenberger and Hendrick will present short talks and then field questions.  No personal Facebook account is required to join the session, which is free and open to the public.

"This is all about the arthropods, both the pests and beneficials that they study in the rice and alfalfa fields," said Tabatha Yang, education and outreach coordinator for the Bohart Museum of Entomology. "Most of the focus is on insects, but tadpole shrimp in rice fields also will be discussed." A virtual family craft activity is also planned.

"I will be discussing some of the insect (or arthropod) problems faced by growers of rice in California and some of the challenges in managing them, Grettenberger said. "In rice, some of the key arthropod pests are tadpole shrimp, which can turn what would have been a lush stand if rice into a poor stand with a lot of floating seedlings. Meanwhile, later in the year, armyworm caterpillars, the larvae of a moth, can chew on rice leaves and destroy plants. I'll discuss some of the ongoing work to better understand and manage these pests."

Grettenberg's fields of expertise include field and vegetable crops; integrated pest management; applied insect ecology, and biological control of pests. (See Spotlight on Ian Grettenberger.) Among his current grants:

• Protection of rice from invertebrate pests
• Insecticide resistant alfalfa weevils in the western United States: Quantifying the scope of resistance and implementing a plan to manage the threat​
• Management of key cotton arthropod pests with insecticides and acaricides, a proactive approach to prepare for the invasion of the tomato leafminer (Tuta absoluta)  into California
• Detection, biology and control of the exotic Swede midge (Contarinia nasturtii) for California cole crops
• Management of the western spotted and striped cucumber beetle in melon production
• Biological control of the bagrada bug
• Insecticide resistance monitoring and evaluation of efficacy of current chemical tactics for managing aphids and thrips in lettuce

Grettenberger joined the UC Davis Department of Entomology and Nematology in January 2019. Grettenberger, who fills the vacated position of Larry Godfrey (1956-2007), received his bachelor of science degree in biology, with an ecology, evolution and organismal emphasis (honors program) in 2009 from Western Washington University, Bellingham, Wash., and his doctorate in entomology in 2015 from Pennsylvania State University, State College, Pa. He served as a postdoctoral researcher in the Godfrey lab and later, the Frank Zalom lab, before accepting his current appointment of assistant Cooperative Extension specialist.

What sparked his interest in entomology? "I had biologist parents, and was drawn into entomology at a pretty young age," Grettenberger said. "I spent plenty of time looking in flowers and turning over logs looking for insects. Once I started thinking about going to graduate school for entomology, I decided to focus on the intersection of agricultural entomology and insect ecology. I wanted to work on applied issues in entomology."

Hendrick, a second-year graduate student in the Grettenberger lab, received her bachelor's degree in iInternational studies at North Carolina State University, and also spent a semester at Nagoya University in Japan (she minored in Japanese).

"I got my start in entomology completely by chance!," Hendrick related. "I needed a science credit and happened to pick a class called 'Insects and People.”' That class really helped me to reframe the way I thought about insects and appreciate what interesting little critters they are. Through that class, I was also able to get a job as an undergraduate assistant in an entomology lab. I worked in a specialty crops lab, where I developed interests in integrated pest management and invasive species. I now study insecticide resistance in the alfalfa weevil, and I'm excited to share what I've learned through this outreach event!"

Grettenberger, Yolo County Farm Advisor Rachael Freeman Long and Madi Hendrick recently wrote a piece in the UC Agricultural and Natural Resources (UC ANR) blog, Alfalfa and Forage News, "A (Virtual )Update on Worms, Weevils an Aphids in Alfalfa."

"This year, the Kearney Research and Extension Center Alfalfa and Forage Field Day went virtual," Grettenberger wrote. "Attendees did not get the chance to look out over lush fields of alfalfa or towering plantings of sorghum, but they get did an update on ongoing work in alfalfa and other forages. Our team put together a rapid-fire video to discuss what are typically the key insect pests in California alfalfa: summer worms, alfalfa weevils, and aphids."

The summer worms in alfalfa include the summer worms: Western yellowstriped armyworm, beet armyworm and alfalfa caterpillar. Another key pest is the alfalfa weevil. The trio also discussed  aphids and their natural enemies, including lady beetles, aka ladybugs).

Pests of rice include armyworms, aster leafhoppers, crayfish, rice leafminers, rice seed midges, rice water weevils and tadpole shrimp.

The Bohart Museum, directed by Lynn Kimsey, UC Davis professor of entomology, is located in Room 1124 of the Academic Surge Building on Crocker Lane, UC Davis campus, but is temporarily closed. The museum houses nearly eight million insect specimens; a live "petting zoo" of Madagascar hissing cockroaches, walking sticks and taranatulas; and a gift shop stocked with insect-themed T-shirts, books, posters, jewelry, candy and insect-collecting equipment. 

More information on the Bohart Museum's virtual presentation is available on its website or by contacting Yang at tabyang@ucdavis.edu.

Resources: 

• Alfalfa and Forage News: A (Virtual) Update on Worms, Weevils and Aphids in Alfalfa (By Ian Grettenberger, Rachael Freeman Long and Madi Hendrick, Sept. 20, 2020) (See video on same page)
• Alfalfa and Forage News: Natural Enemies Are Important for Control of the Aphid Complex in Alfalfa--A Case Study (By Ian Grettenberger, Rachael Freeman Long, Daniel Putnam and Rob Wilson, April 7, 2020)
• UC Statewide Integrated Pest Management Program: How to Manage Pests of Alfalfa
• UC Statewide Integrated Pest Management Program: Insects and Other Pests of Rice

 

Natural landscapes surrounding vineyards can decrease pest outbreaks and depress pesticide use, according to a UC Davis paper published in the current edition of the journal Ecology Letters.

A five-member team led by postdoctoral researcher Daniel “Dani” Paredes of the Daniel Karp lab, UC Davis Department of Wildlife, Fish and Conservation Biology (WFCB), analyzed a 13-year government database to assess how the landscapes surrounding 400 Spanish vineyards influenced European grapevine moth (Lobesia botrana) outbreaks and insecticides application rates.

The article, "Landscape Simplification Increases Vineyard Pest Outbreaks and Insecticide Use," is now online.  

“At harvest, we found pest outbreaks increased four-fold in simplified, vineyard-dominated landscapes compared to complex landscapes in which vineyards are surrounded by semi-natural habitats,” said lead author Paredes, who holds a doctorate in environmental sciences (2014) from the University of Granada, Spain.  “Overall, our results suggest that simplified landscapes increase vineyard pest outbreaks and escalate insecticide spray frequencies. In contrast, vineyards surrounded by more productive habitats and more shrubland area are less likely to apply insecticides.”

Landscapes around farms are rarely managed to suppress damaging crop pests, partially because researchers rarely measure the key variables that drive farming decisions. This paper, however “shows how using really huge datasets—in this case generated by government employees working with farmers in Spain--can reveal how natural habitats surrounding agriculture can shape pest outbreaks and pesticide use in vineyards,” said co-author Jay Rosenheim, distinguished professor in the UC Davis Department of Entomology and Nematology.

Their results suggest that landscape simplification could affect not only farm yields, but also  environmental and human health. They noted that insecticide applications doubled in vineyard-dominated landscapes but declined in vineyards surrounded by shrubland. “Habitat conservation thus represents an economically and environmentally sound approach for achieving sustainable grape production in Spain,” said Karp.

Why might pests be more of a problem on vineyards surrounded by more vineyards? One possibility is that vast stretches of vineyards allow pest populations to build up quickly. Another possibility is that simple vineyard landscapes may not contain enough resources to support predatory insects that natural control vineyard pests. Whatever the reason, it seems clear that “cultivating crops in monoculture creates the perfect conditions for specialist pest outbreaks,” they related, so “farmers have consistently turned to insecticides to maintain high yields under constant pest pressure.” 

A solution? At an individual level, farmers may better control L. botrana populations through planting native vegetation in and around their farm. Ideally, they would coordinate with each other to maintain and/or restore large patches of productive, shrubland habitats in the surrounding landscape. 

Other co-authors are Rebecca Chaplin-Kramer, Natural Capital Project, Stanford University; and Silvia Winter, Institute of Plant Protection, University of Natural Resources and Life Sciences, Vienna, Austria.

Their work was financed by the research project SECBIVIT, or “scenarios for providing multiple ecosystem services and biodiversity in viticultural landscapes,” and a National Science Foundation/USA grant. 

Sometimes distant relationships are better than close relationships. 

Persimmons, asparagus, figs and other crops distantly related to native California plants attract fewer pests and diseases than the closer kin, and thus receive fewer pesticide treatments, according to a newly published article by two UC Davis-linked scientists in the Proceedings of the Natural Academy of Sciences (PNAS). 

Co-authors Ian Pearse, research ecologist with the U.S. Geological Survey and a UC Davis alumnus, and Jay Rosenheim, UC Davis distinguished professor of entomology, analyzed the 2011-2015 state records of pesticide applications of 93 major California crops. 

 “We hypothesized that California crops that lack close relatives in the native flora will be attacked by fewer herbivores and pathogens and require less pesticide use,” said Rosenheim, a 32-year member of the UC Davis Department of Entomology and Nematology faculty and a newly elected fellow of the Entomological Society of America. 

Rosenheim and Pearse examined the pesticide applications against arthropods, pathogens, and weed plants and compiled the data into a comprehensive analysis. 

Their findings appear in the PNAS article, “Phylogenetic Escape from Pests Reduces Pesticides on Some Crop Plants,” published Oct. 12. “Phylogenetic relationship” refers to the relative times in the past that species shared common ancestors. 

“It is well understood that many of the insect pests and diseases that attack our crops are often invasive species that come from overseas,” Rosenheim explained. “Almost all crops grown in California have been domesticated from wild plants whose area of origin is overseas, and many of the invading pests come from the original home of the wild ancestor of the now domesticated crop plant.” 

“In contrast, our study focuses on the roughly half of all herbivores and diseases that attack California crops and that are actually native to California.  These organisms originally attacked members of the native California flora, but have now shifted to attack a novel host: the crop plant.” 

However, “host shifts aren't always easy,” Rosenheim said. “It's relatively easy to shift to attack a close relative of a native host plant, but it's relatively hard to shift to attack a very different host plant.” 

Said Pearse: “Our study shows that crops like dates, asparagus, figs, kiwis, or persimmons that are distantly related to native California plants--and thus separated by many million years of independent evolution-- are colonized by fewer pests and diseases.” 

These crop plants, the scientists said, are “too different” to be attacked readily.  As a result, fewer pesticide applications are needed to protect those crops.  “Thus, we can capitalize on an understanding of the evolutionary relatedness of crops and native plants to find crops that will suffer less attack, and that can therefore be grown with less use of toxic pesticides,” Pearse pointed out. 

"The crops that require the most pesticide applications, Pearse said, "are those, like artichokes, blackberries, and sweet corn, that have close relatives in the Californian flora and are of high economic value per acre."

California's top agricultural crops include almonds, grapes, lettuce, strawberries, tomatoes and walnuts. 

Rosenheim said persimmons are a good example “of the phenomenon we've studied: they have very, very few pests--almost zero in my experience--and that's probably because persimmons have no close relatives in the California native plant community.” 

Pearse, a 2005 Fulbright scholar who received his doctorate in ecology from UC Davis in 2011, studying with Professor Rick Karban, joined the U.S. Geological Survey in Fort Collins in 2016. He focuses his research on invasive species and plant-insect interactions.  Rosenheim researches insect ecology, with a focus on host-parasitoid, predator-prey, and plant-insect interactions, with direct applications to biological control.

Their abstract:

“Pesticides are a ubiquitous (found everywhere) component of conventional crop production but come with considerable economic and ecological costs.  We tested the hypothesis that variation in pesticide use among crop species is a function of crop economics and the phylogenetic relationship of a crop to native plants, because unrelated crops accrue fewer herbivores and pathogens.  Comparative analyses of a dataset of 93 Californian crops showed that more valuable crops and crops with close relatives in the native plant flora received greater pesticide use, explaining roughly half of the variance in pesticide use among crops against pathogens and herbivores.  Phylogenetic escape from arthropod and pathogen pests results in lower pesticides, suggesting that the introduced status of some crops can be leveraged to reduce pesticides.”

Miridae, a company founded and owned by UC Davis-trained ecologist Billy Krimmel, won the highly competitive 2020 Award of Excellence for Communication from the American Society of Landscape Architects (ASLA) for its Seed Bank Living Wall at DPR Construction, Sacramento.   

The ASLA awards, judged by a jury of professionals, honor the best in landscape architecture from around the globe. ASLA celebrated the winners at its conference, held Oct. 2-5 in Miami Beach, Fla.

A number of nationally known landscape architecture firms competed for the award “which is some nice icing on the cake!”  commented Krimmel, who founded the company in 2015, a year after receiving his doctorate in ecology from UC Davis.

Miridae, led by UC Davis and Stanford graduates, is a diverse and interdisciplinary team of ecologists, landscape architects and builders.

California Native Species

The seed bank, using California native species, challenges the concept of a typical ‘living wall' by highlighting dormant seeds as living plants instead of the leaves and stems normally associated with living plants, Krimmel said. 

With a collaborative team of artists and fabricators, Krimmel and his team challenged the look and feel of the traditional “green” living wall and instead proposed a living wall of dormant plant seeds. 

Krimmel describes the project as “a celebration of place,” specifically Sacramento's Central Valley. The project is located at DPR's midtown Sacramento location at 1801 J St.

“The dormant seeds in the wall, physically held within the roots of each highlighted plant species, may extend beyond the life of the building,” Miridae writes on its website. “It is a reserve for the future and a concept that challenges how we think about what an individual plant is and how we cohabitate with nature.” 

The concept “arms our client, DPR Construction, with a new mission to support native habitat!” Krimmel said. DPR, founded in 1990, is a national technical builder that specializes in highly complex and sustainable projects. Its Sacramento headquarters are at the corner of 18th and J streets. DPR is named for its founders, Doug Woods, Peter Nosler and Ron Davidowski (the D, P and R). 

Featured in Magazine and Website
Landscape Architecture Magazine spotlighted the Miridae project in a full-page spread in the print copy, and it is also featured on ASLA's website. 

From the ASLA website: “Our project began with a call for a ‘living wall' from a prominent national construction company moving their regional headquarters to Downtown Sacramento. They wanted a living wall that was sustainable, provided a sense of location, and required little maintenance. We wanted to create something that motivated the company to use habitat-crucial native plants in their construction projects and that would highlight the beauty and the benefits of these often-overlooked species. Thus, we decided to pursue a different concept for this living wall, one we have titled, the Seed Bank. Challenging the design standard that highlights the leaves, stems, and flowers we typically associate with plants, the Seed Bank uses dormant, live seeds of important California native species to highlight the unseen elements of these plants and to organize them in a spatially-explicit way that ties the local species to their natural and potential distributions.”

The native plants used in the Seed Wall: 

• Arroyo Lupine
• Purple Needlegrass
• California Poppy
• Narrow Leaf Milkweed
• Deergrass
• Common Yarrow
• Vinegarweed
• Hairy Evening Primrose
• Common Fiddleneck
• Bolander's Sunflower
• Turkey Mullein
• Common Madia
• Creeping Wild Rye
• Tomcat Clover
• Blue Wild Rye

Creating Habitat for Native Species
Krimmel founded the company with the intention of “creating habitat for native species within human-occupied areas and engaging people with the species interactions occurring in these habitations.”

The name, Miridae, is Latin for a family of insects known as “plant bugs,” or mirids, which Krimmel researches. One of the most well-known mirid is the lygus bug, a serious pest of cotton, strawberries and alfalfa. 

Of his company, Krimmel says: “We create habitat for, and engage people with, native plants and the wildlife they support. We do this by tying together design, science, and high-quality construction to create landscapes that are beautiful, resilient, and ecologically powerful.” 

His goal, with each project, is to “come one step closer to creating a network of habitat gardens and migration corridors to support resilient populations of native species.” 

At UC Davis, Krimmel studied with Jay Rosenheim, distinguished professor, Department of Entomology and Nematology. Focusing his research on native plant-insect interactions, he wrote his dissertation on “Plant Traits and Plant-Herbivore-Omnivore Interactions.” He holds a bachelor of science degree in human biology (2008), with honors, from Brown University, Providence, RI. 

Krimmel continues to be active in the research community, writing peer-reviewed journal articles on native plants and insects, and a quarterly column in the peer-reviewed journal Grasslands. “My vision is to connect landscaping with science and restoration,” he said. 

With Miridae, he has overseen the design and building of more than 150 landscape projects throughout the Sacramento and Bay Area regions. He has severed as a board member and chair of outreach and development for the California Native Grasslands Association since 2015. 

The UC Davis alumnus regularly presents at the Wildflowers and Conservation Biology to American River College, and the Waterwise Gardening Workshop series by the Yolo Research Conservation District. He also presents at a UC Davis course, Natural RX, discussing nature's healing abilities; and at the Hedgerow Farms Field Day on insect interactions in native gardens.