- (Public Value) UCANR: Building climate-resilient communities and ecosystems
This is the most recent status report of theKuroshio Shot Hole Borer in the Tijuana River Valley of San Diego. For the full report go to: https://trnerr.org/kshb/
The Ecology and Management of the Kuroshio Shot Hole Borer
in the Tijuana River Valley
2019-20 (Year 5)
John Boland and Kellie Uyeda
This report presents the current status of the Kuroshio Shot Hole Borer (KSHB, Euwallacea kuroshio, Coleoptera: Scolytidae) in the Tijuana River Valley. It provides current rates of KSHB infestation; documents the current state of post-KSHB recovery in the most impacted forests in the valley; compares the current data with data collected over the past five years; and uses GIS technology for the first time to accurately map the spread of the KSHB in the valley.
This report is the fifth in a series of annual reports about the KSHB in the valley. It adds to and further develops four main storylines about the KSHB in the valley:
1. The KSHB in the valley went through a rapid boom-and-bust cycle. Annual surveys of infestation rates in the field and annual calculations of canopy damage from satellite images show that the KSHB population went through a rapid outbreak and a rapid decline over a five-year period. The infestation rates peaked in Fall 2016 and the canopy damage was greatest between 2016 and 2017. The early increase in population was characterized by the KSHB's presence in the Wet Forests and the swift damage to these forests (see frontispiece). The later decrease in population was characterized by the KSHB's presence in the Dry Forests and the slower damage to those forests. The KSHB population decline appears to be due to the KSHB depleting their preferred host trees and not reinvading the recovering host trees in the Wet Forests. This boom-and-bust cycle occurred naturally, with no management interventions to control the spread or severity of the outbreak.
2. The willow forests that were extensively damaged by the KSHB are responding with vigorous regrowth. Since the KSHB heavily damaged the Wet Forests in 2015-17, there has been extensive willow forest recovery in three ways: by the survival of a few, scattered mature infested trees (‘Big Trees'); by the resprouting of mature KSHB-damaged trees (‘resprouts'); and by the seeding of new trees (‘seedlings'). The frontispiece shows the striking recovery of one of the Wet Forests. Some of the forests have recovered so much in just four years that they are now similar to their pre-KSHB stature.
3. The KSHB has not substantially reinfested the recovering willow forests. Even though others predicted that all of the trees in the recovering Wet Forests would be quickly reinfested, only 3% of the Big Trees, 2% of the resprouting trees, 1% of the young trees, and 0% of the seedlings were infested with KSHB in 2019. This unexpected result begs the question: Why are the recovering willows not being attacked by the KSHB? In this report we suggest three possible reasons.
4. The invasive plant, Arundo donax, is now a major problem. Willow trees are arundo's only competitors in the valley, and when the KSHB attacked and heavily damaged the willows it allowed arundo to flourish more than ever before. Our main recommendation for the park managers in the valley is to control the arundo on their property. To assist them we provide a map of the current distribution of arundo using satellite images and object-based imagery analysis (OBIA) software.
The research reported here is unique among KSHB studies. It involves detailed and long-term field surveys of the KSHB invasion in one valley, documents an entire boom-and-bust outbreak of the KSHB and describes the damage to and recovery of the forests. This report also discusses the six most important ecological findings and suggests that incorporating these findings into the existing predictive numerical model would make the model more accurate. Finally the report presents several recommendations for needed future research and for immediate management actions.
‘Bee' thankful for the evolution of pollen
Missouri U. researchers discover wildflower's spiny pollen
adapts to help plants reproduce
Over 80% of the world's flowering plants must reproduce in order to produce new flowers, according to the U.S. Forest Service. This process involves the transfer of pollen between plants by wind, water or insects called pollinators -- including bumblebees.
In a new study, researchers at the University of Missouri discovered spiny pollen -- from a native wild dandelion species in the southern Rocky Mountains -- has evolved to attach to traveling bumblebees. Using a highly detailed electron scanning microscope, the research team could observe the microscopic surface of the spiny pollen, which otherwise looks like yellow dust to the naked eye.
"The spiny pollen actually acts like Velcro," Lynn said. "So, when bees are harvesting pollen for food, this pollen is sticking to their hair. It's a great example of mutualism where the plant needs the pollinator to reproduce and the pollinator needs the plant for its food."
The researchers plan to study how a bumblebee's hairs contribute to this process.
For more on how clever plants are, check out Michael Pollan's Botany of Desire.
What a lot of bees. These are Miner or Chimney bee nests. Another type of Digger bee, these nests are from Santa Paula Canyon thanks to Nathan Lurie
The hills are alive with the sound of BEE-EEZZE. And often they are found crawling on the ground, as is the case of Digger Bees. At this time of year, they might be seen along the margins of avocado orchards, near hiking trails or in undisturbed areas of citrus orchards. They are called Digger Bees commonly, but this is just a generic name for a large group of bees that nest in the ground. There are many genera and species and because of the general lack of study of these bees they are lumped under the name Digger for lack of any greater knowledge and naming of them.
There are several kinds of small hairy or metallic bees that dig into the soil to nest, hence the common name, digger bees. They are a diverse group that comes from different families and the term digger bee can include the andrenid bees, halictid bees, and colletid bees such as the plasterer and yellow-faced bees. These are solitary bees and native pollinators that are active early in the season. Each female digs a cylindrical underground tunnel as a nest where she reproduces (as opposed to social bees such as honey bees where only the queen reproduces and maintains a colony with the help of sterile workers). Although solitary, they form colonies that may have several hundred nests in one spot, but all nests are independently owned.
The subterranean nest is provisioned with a mixture of nectar and pollen collected from nearby flowering plants. This "bee-bread" is food for the bee's offspring (larvae) that develop in the underground chamber and emerge as adults the following year.
Digger bees are 1/4 to 1/2-inch-long and variable in color (mostly shiny metallic or dark, but some with markings of white, yellow or reddish brown). There is one generation of digger bees per summer and once the adults finish perpetuating the species by laying eggs of the next generation there will be no activity till the following spring.
Digger bee nests are commonly located in areas where grass and mulch are scarse, either from too much shade, previous drought conditions or other stress. Most of them like to fly around their airspace at different times of the day, something to do with mating, air temperature or staking territory. They often travel great distances to forage.
The threat of being stung by digger bees is unlikely. The bees are docile and not likely to sting unless handled or threatened. There is no nest guarding behavior or attack behavior like there is with social insects such as honey bees and yellowjacket wasps.
Another recent colony find was comprised of another digger bee.
In the case of this bee find, they are possibly Diadasia bituberculata – as suggested by Robin Thorpe, UCD entomologist. They are uncommon in the rest of the world, but found here in California and the western US. There are over 1,000 digger bee species.
Diadasia Digger Bee "Colony", Thanks to Pest Control Adviser Jane Delahoyde's friend.
- Author: Alli Fish
The Buzz about Hedgerows
Hedgerows are an approved practice under California Department of Agriculture's Healthy Soils Grant Program. That means, growers are eligible to receive grant funding for planting hedgerows. But what exactly are the benefits of hedgerows and why are they worth planting? As a perennial planting it can have immediate impacts on the soil, but what else? The answer lies large in the pollinators and beneficial insects they attract.
The most basic definition of a hedgerow is dense vegetation planted in a linear design. Perennial grasses, shrubs, and even short trees are all candidates for hedgerow plantings, provided they meet the conditions of the local climate and soil. Growers plant hedgerows to achieve one or more of the following desired outcomes:
- To increase habitat for pollinator and beneficial insect populations
- To create a living barrier or fence
- To reduce chemical drift or odor movement
- To intercept airborne particulate matter
- To act as a low windbreak or reduce dust
- To increase carbon storage in biomass and soils
- To provide food, shelter, and shade for aquatic organisms in nearby aquatic habitats
All of these benefits make the case for planting hedgerows on any agricultural operation. In Ventura County, avocado growers stand to see a compelling case for hedgerow plantings with particular attention to pollination services.
There are many different pollinators who visit avocado flowers, from native bees to flies to honey bees. Some come in the daytime, others visit at night. In the likelihood that honey bees and other pollinators will continue to decline, it is imperative to study the importance of native pollinators on key crops and identify ways to increase habitat for resident populations (NRC 2007; Nordhaus 2011; PHTF 2015; Koh et al. 2016; Sánchez-Bayo and Wyckhuys 2019; DiBartolomeis et al. 2019; Garibaldi et al. 2013). This information not only helps the pollinator populations thrive, but helps avocado growers acquire free increased pollination services for fruitful trees. Several researchers have published accounts of increased pollinator diversity and numbers in hedgerow and field edge planting studies across various agricultural systems (Heller et al. 2019; Long and Anderson 2010; Long et al. 2017; Williams et al. 2015).
In Ventura County, we are seeing some fascinating and relevant research around the impact of hedgerows on pollinators in avocado orchards. A collaborative research project involving Dr. Ben Faber, Avocado Advisor for UC Cooperative Extension Ventura County, and Dr. Gordon Frankie, professor and research entomologist at UC Berkeley and lead investigator of the UC Berkeley Urban Bee Lab, seeks to understand long-term impacts of hedgerows on pollinators of avocado trees. The project, which began in 2014 with three participating avocado ranches, has indicated increased pollinator activity, increased native bee populations, and increased diversity of species with the presence of hedgerow plantings (Frankie, Faber et al. 2020). The results indicate the importance of diversity of pollinator species, not just the honeybee, to avocados. In continuing this research, the team seeks to address the unanswered questions of which pollinators are the most effective at pollinating avocados and which are the most effective at influencing fruit set. A particularly exciting and novel aspect of this project is looking at whether or not there are nocturnal pollinators visiting California avocados. Nocturnal pollinators have been well documented in New Zealand (Pattemore et al, 2018), but none have been yet recorded in California avocados.
Maintaining hedgerows is critical to providing additional habitat for an abundance of pollinators. Creating and maintaining that hedgerow and for which pollinators can be a daunting task to embark on. Luckily for avocado growers, Dr. Frankie and Dr. Faber's team are working with Southern California growers to develop a pollinator garden manual. The manual will provide clear pictures of key pollinators and key plant species that pollinators are drawn to. Detailed imagery, descriptions, and maintenance tips will help make the decision making around planting a hedgerow much easier.
Speaking of selections, there are key plants that are drought-tolerant, easy to maintain, and well-suited for Ventura County's climate. See the table below for some ideas.
Table 1. Main Native Bee Plants Installed in Avocado Orchards 2014-2019
We seek to increase biodiversity, build soil health, and reduce energy use in our agricultural systems to improve our resiliency to climate change impacts, pests, and disease. To keep farming in our families and in our futures. Planting hedgerows is good for the pollinators, which is good for the bottom line and long-term success of the operation.
If you are an avocado grower interested in learning more about the pollinator research project, please contact Dr. Gordon Frankie at the UC Berkeley Urban Bee Lab email@example.com.
Interested in planting hedgerows on your property? You may be able to qualify for a grant through CDFA's Healthy Soils Grant Program to plant hedgerows. Please contact Jamie Whiteford with the Ventura County Resource Conservation District at firstname.lastname@example.org more information on how to apply. For those in other areas, Technical Assistance providers are able to discuss the values of hedgerows and funding opportunities for installing them in other agricultural situations: http://ciwr.ucanr.edu/Programs/ClimateSmartAg/TechnicalAssistanceProviders/
Bombus vosnesenskii photo by Rollin Coville
DiBartolomeis, M., S. Kegley, P. Mineau, R. Radford, and K. Klein. 2019. An assessment of acute insecticide toxicity loading (AITL) of chemical pesticides used on agricultural land in the United States. PLoS ONE 14(8): e0220029. https://doi.org/10.1371/journal.pone.0220029.
Frankie, G., B. Faber, J. Pawelek, R. Thorp, R. Coville, C. Jadallah, E. Takele, S. I. Rios, T. Bean. 2020. Native Pollinators of California Avocado as Affected by Introduced Pollinator Gardens. International Society of Horticultural Sciences Congress. Acta Horticulturae.
Garibaldi, L.A., I. Steffan-Dewenter, R. Winfree, and 47 other authors. 2013. Wild pollinators enhance fruit set of crops regardless of honey bee abundance. Science 339:1608-1611.
Heller, S., N. K. Joshi, T. Leslie, E. G. Rajotte and D. J. Biddinger. 2019. Diversified Floral Resource Plantings Support Bee Communities after Apple Bloom in Commercial Orchards. Scientific Reports 9 Article number: 17232.
Koh, I., Lonsdorf, E. V., Williams, N. M., Brittain, C., Isaacs, R., Gibbs, J., Ricketts, T. H. 2016. Modeling the status, trends, and impacts of wild bee abundance in the United States. Proceedings of the National Academy of Sciences 113:140–145.
Long, R. F. and J. Anderson. 2010. Establishing Hedgerows on Farms in California. UC ANR Pub 8390, Oakland, CA. http://anrcatalog.ucanr.edu/Details.aspx?itemNo=8390
Long, R., K. Garbach and L. Morandin. 2017. Hedgerow benefits align with food production and sustainability goals. California Agriculture 71:117-119. 10.3733/ca.2017a0020.
NRC. 2007. Status of Pollinators in North America. National Research Council of the National Academies. National Academies Press, Washington, D.C.. 307 p.
Nordhaus, H. 2011. The Beekeeper's Lament. Harper Perennial, NY. 269p.
Pattemore, D., M. N. Buxton, B. T. Cutting, H. McBrydie, M. Goodwin, A. Dag. 2018. Low overnight temperatures associated with a delay in ‘Hass' avocado (Persea americana) female flower opening leading to nocturnal flowering. Journal of Pollination Ecology 23(14): 127-135.
PHTF: Pollinator Health Task Force. 2015. Pollinator Research Action Plan. The White House.
Sánchez-Bayo, F. and K. A. G. Wyckhuys. 2019. Worldwide decline of the entomofauna: A review of its drivers. Biological Conservation 232:8-27.
Williams, N. M., K. L. Ward, N. Pope, R. Isaacs, J. Wilson, E. A. May, J. Ellis, J. Daniels, A. Pence, K. Ullmann, and J. Peters. 2015. Native wildflower plantings support wild bee abundance and diversity in agricultural landscapes across the United States. Ecological Applications 25: 2119–2131
Current status of
Laurel Wilt: A Disease of Avocado
Please find enclosed links to a recent on-line meeting of researchers from forestry and avocado production system perspectives on current laurel wilt research. The goal of the meeting was to briefly share information on current basic and applied research and ideas for controlling or mitigating the laurel wilt pathogen and the ambrosia beetle vectors. Below is the agenda.
Laurel wilt is a notorious example of the destructive capacity of beetle-borne fungi. Even more importantly, there is a vibrant community of researchers studying it! At this meeting we will host scientists and students that are actively solving the mysteries of this epidemic. We will hear about many topics, from glowing transgenic pathogen strains to field detection with sniffer dogs.
We hope that the laurel wilt community will also benefit from what our BBM Network has to offer. Exchanging results and experiences is important for the PIs, but perhaps even more for the students – designing and executing a laurel wilt related-project takes a long time, so it might be beneficial to get feedback earlier than at the publication stage. We see repeated mistakes that could be prevented, and old questions that would have been answered, if we talked more as a community. And how about people studying different ambrosia symbioses, beetles or pathogens? There is a lot of overlap but little information exchange with those outside of our field.
INTRODUCTION AND WELCOME
- 9:00 Jiri Hulcr: Short introduction to the Bark Beetle Mycobiome group (5 minutes)
- Josh Konkol: GFP strain, colonization of the host plant by R. lauricola
- Jeff Rollins: Studying R. lauricola pathogenesis through comparative genomics and transcriptomics
- Qiang Wang: CRISPR-homologous recombination methods and deletion of genes from R. lauricola
- Ross A. Joseph: Swap of multiple GFP-labeled strains inside the vector
- Octavio Menocal Sandoval: Breeding Xyleborus, behavior of mating and symbiont swap
- Daniel Carrillo: Laurel wilt vectors in avocado
- Kirsten Stelinski: TBD
- Denita Hadziabdic: Laurel wilt advancing North
- Robin Choudhury: LW dispatch from the Texas front
- Andrés Lira Noriega: Modelling for risk assessment of laurel wilt in Mexico
- Jason Smith: Redbay heritable resistance and rebounding populations
- Caterina Villari: Detection of laurel wilt pathogen in the field with LAMP
- DeEtta (Dee) Mills: Detector dogs
- Pedro Parra Giraldo: Culture-independent Laurel Wilt diagnosis in avocado groves
- Romina Gazis: Testing “Out-Of-The-Box” Ideas to Control Laurel Wilt of Avocado
- José Luis Olivares-Romero: Synthesis of novel insecticides for the management of ambrosia beetles
- Jonathan Crane: Laurel wilt status in avocado groves and grower-initiated control
- Xavier Martini and Derrick Connover: Push-pull system to protect redbay and avocado against Laurel Wilt