Posts Tagged: IPM
The scent that could save California’s avocados
Scientists search for pheromone to disrupt insect mating
UC Riverside scientists are on the hunt for a chemical that disrupts “evil” weevils' mating and could prevent them from destroying California's supply of avocados.
Avocado weevils, small beetles with long snouts, drill through fruit to lay eggs. The weevil grubs or larvae bore into avocado seeds to feed, rendering everyone's favorite toast topping inedible.
“They're extremely hard to control because they spend most of their time deep inside the fruit, where they're very well protected from insecticides and natural enemies,” said UCR researcher Mark Hoddle, a UC Cooperative Extension entomology specialist.
Not only are the insects reclusive, they are also understudied, making information about them hard to come by. “All books on avocado pest management will tell you these weevils are bad. They're well recognized, serious pests of avocados, but we know practically nothing about them,” Hoddle said.
One strategy for controlling pests is to introduce other insects that feed on them. However, that is unlikely to work in this case. “Natural enemies of these weevils seem to be extremely rare in areas where this pest is native,” Hoddle said.
To combat avocado weevils in Mexico, an area where they are native, and to prevent them from being accidentally introduced into California, Hoddle is working with Jocelyn Millar, a UCR insect pheromone expert. They are leading an effort to find the weevil's pheromone, with the goal of using it to monitor these pests and prevent them from mating in avocado orchards.
Pheromones are chemicals produced and released into the environment by an insect that can be “smelled” by others of its species, and affect their behavior.
“We could flood avocado orchards with so much pheromone that males and females can't find each other, and therefore can't reproduce,” Hoddle said. “This would reduce damage to fruit and enable growers to use less insecticides.”
Alternative control strategies could include mass trapping, using the pheromone as a lure, or an “attract-and-kill” approach, where the pheromone attracts the weevils to small sources of insecticide.
The work to identify, synthesize and test this pheromone in the field is supported by grants from the California Department of Food and Agriculture, as well as the California Avocado Commission.
An initial phase of the project sent Hoddle to a base of operations three hours south of Mexico City, an area with large weevil populations. Using a special permit issued by the USDA, Hoddle brought weevils back to UCR's Insectary and Quarantine facility.
Hoddle and Sean Halloran, a UCR entomology researcher, captured the chemicals that avocado weevils release into the air. Possible pheromone compound formulas were identified from these crude extracts and are now being synthesized in Millar's laboratory.
“Weevil pheromones have complicated structures. When they're made in a lab, they can have left- or right-handed forms,” said Hoddle. Initially, Millar's group made a mixture of both forms to see if the blend would work as an attractant, as it is far cheaper to make the blend than the individual left- or right-handed forms.
Field work in Mexico with the pheromone cocktail by Hoddle, his wife Christina Hoddle, an associate specialist in entomology, and Mexican collaborators did not get a big response from the weevils, suggesting that one of the forms in the blend could be antagonizing the response to the other.
As the next step, the researchers plan to synthesize the individual forms of the chemicals and test the insects' response to each in Mexican avocado orchards.
Because the levels of avocado imports from Mexico are increasing, the risk of an accidental weevil invasion is rising as well. Hoddle is hopeful that the pheromone will be successfully identified and used to lower the risk this pest presents to California's avocado growers.
“We've been fortunate enough to be awarded these grants, so our work can be implemented in Mexico and benefit California at the same time,” Hoddle said. “The tools we develop now can be used to make sure crops from any exporting country are much safer to import into California.”
/h3>After shothole borer invasion, UC Irvine becomes ‘perfect testing ground’
Results help inform best practices for managing the disease-causing beetle
The University of California, Irvine campus is home to a vast urban forest consisting of approximately 30,000 trees located in a mix of landscape, riparian and open space settings. In the mid-2010s, that forest came under threat from an invasive species of beetle that arborists and pest researchers were just learning about – the polyphagous shothole borer.
The tiny beetles, which may have arrived in California from their native Southeast Asia via infested shipping materials, tunnel into trees and introduce a fungus that serves as food for adult beetles and their larva.
As the fungus grows, it colonizes the tree's vascular system, blocking transport of water and nutrients. This causes a disease called Fusarium dieback that can kill branches or entire trees.
One reason the beetles were such a threat at UCI was the high number of sycamores on campus, especially in Aldrich Park at the campus center. Hundreds of cottonwoods, native willows, golden rain and coral trees also were affected. In total, the beetles attacked more than 2,000 trees, including 75 different tree species.
A variety of approaches to controlling beetle
To better understand and tackle this problem, UCI's Facilities Management department and Office of Environmental Planning and Sustainability collaborated with researchers affiliated with UC Agriculture and Natural Resources and UC Cooperative Extension. In addition, pesticide-manufacturing companies, pest control advisers and arborists provided materials and labor to help offset the cost of research.
“UCI was the perfect testing ground to determine integrated pest management strategies for this beetle/disease complex,” said John Kabashima, UCCE environmental horticulture advisor emeritus. “Our research was multifaceted, delving into early detection, monitoring and sampling, and cultural and chemical management.”
Kabashima said UCI provided the researchers with “a lot of freedom” to try a variety of approaches and study the results over time.
“We could cut down and sample trees or leave selected infested trees alone; we explored a variety of pesticide/fungicide combinations and application techniques,” he said. “That freedom resulted in many of the management solutions that are used today to effectively control this pest.”
UCI and the researchers also established a full inventory of affected trees on campus, evaluating severity of infestation by the number of entry/exit holes and signs of dieback. One important key to management is getting rid of “amplifiers” – heavily infested trees that are both hazardous and a source of beetles to spread to other trees.
“Typically, shothole borer infestations begin with just a few trees that for some reason are highly attractive to the beetles – perhaps based on tree species, tree spacing, irrigation conditions or other factors,” Kabashima said. “Over time, the beetles and fungus multiply largely undetected in those few trees. When the beetle population reaches a critical point and the trees begin to die, the female beetles fly to adjacent trees in a secondary invasion, eventually infesting many trees over a large area.”
An opportunity to diversify UCI's urban forest
At UCI, that initial invasion took place in landscaped areas containing many large, majestic sycamores that were planted when the campus began operations in the mid-1960s.
Over several years, UCI removed 700 heavily infested trees, including many of those historic sycamores, and replaced them with other tree species.
Today, the forest at UCI is very different than it was in 2015. While shothole borers have not been eliminated completely, their presence is reduced significantly, and UCI now has the tools to manage them effectively. Reforestation efforts resulted in a diverse treescape that is not only more sustainable but also beautiful.
“Managing a 1,500-acre campus with 30,000 trees is a never-ending process,” said Richard Demerjian, UCI's assistant vice chancellor, Campus Physical & Environmental Planning. “Our forest continues to evolve, with an ongoing focus on increasing diversity and plant health.”
Demerjian also noted that UCI is now starting to consider planting new sycamore trees on a limited basis.
A primer on effective shothole borer management
Whether managing a forest of thousands of trees or just a few trees, landscape managers and residents can apply many of the lessons learned at UCI to control invasive shothole borers and other tree pests.
- Avoid monocultures. Tree diversity provides beauty and resiliency.
- Keep trees healthy. Proper irrigation and maintenance will keep trees strong and help protect them from shothole borers and other pests.
- Check trees. Look for the common signs and symptoms of infestation such as beetle entry/exit holes. Regular monitoring ensures that infestations are managed early, before they cause dieback or tree death.
- Confirm suspected infestations. Use the detection tool at www.ishb.org.
- Review management options. For trees with low infestation, prune the infested branches and monitor the tree's health over time. In non-riparian, urban settings, consider treating low and moderately infested trees with pesticides/fungicides demonstrated to be effective against the pest-disease complex (A licensed professional will be needed to apply the treatments). Severely infested trees may require removal.
- Call in a professional. A certified arborist or pest control professional would be able to provide recommendations based on the tree's condition. The local county Agricultural Commissioner's Office and UC Cooperative Extension office may have additional knowledge about current shothole borer monitoring and management programs in your area.
- Take care of green waste. The beetles can survive in cut wood for weeks or even months. Proper disposal of green waste includes chipping infested wood, followed by solarizing or composting the chips.
- Replant wisely. Begin planting new trees only after removing all amplifiers and establishing an ongoing monitoring program. Consider the current concentration of tree species when deciding what type of trees to plant.
More detail, key updates in new edition of pesticide safety manual
Publication in English, Spanish prepares private applicators for state exam
Expanded from four chapters in the previous edition to 12, the third edition of Pesticide Safety: A Study Manual for Private Applicators aims to be more than just a study guide.
The manual, available for purchase in English and Spanish, provides much more detail on essential processes and procedures that will help keep applicators safe while using pesticides – as well as reduce environmental impacts from misapplication.
Published by University of California Agriculture and Natural Resources in collaboration with the state's Department of Pesticide Regulation, the manual – intended for members of the agricultural community who own, manage or work on farms that use restricted-use pesticides – also includes substantial updates.
“The information in the book they were using was way out of date,” said writer/editor Shannah Whithaus, senior editor for pesticide safety education with UC ANR's Statewide Integrated Pest Management Program. “Also, the book was much, much shorter than it needed to be, because it wasn't providing enough information for people to safely apply pesticides, given the complexity of the regulatory environment we're in now.”
The new manual reflects important changes to federal and state regulations since the publication of the previous edition in 2006.
“There are significant regulatory updates which help you stay up-to-date with safety rules and standards – and protect your workers from overexposure to pesticides,” said Lisa Blecker, technical editor of the publication, and currently a pesticide safety educator at Colorado State University.
In addition to emphasizing the broader ecological ramifications of improper pesticide use, the manual includes information on subjects that might get short shrift in other manuals, such as the correct calibration of equipment to ensure accuracy of application.
“All of that is now in the book and fully fleshed out,” Whithaus said. “[Applicators] are going to be able to do that much more effectively using the new book, compared to the old one – it was really hard to be thorough in 80-some pages.”
The new edition – totaling more than 200 substantive pages – also features a more streamlined and user-friendly layout modeled after a sister publication, The Safe and Effective Use of Pesticides, written for commercial applicators.
“A significant update is a layout that is not only beautiful, but helps you identify key information you need to know in order to make safe and effective pesticide applications,” Blecker explained.
She highlighted the “knowledge expectations” listed at the beginning of each chapter and in the margins of the book, next to the relevant passages. The statements serve as “visual cues” to help readers learn and retain the material they need to pass California DPR's certification exam for private applicators.
And while the manual functions as an improved study aid for owners, managers and workers who apply pesticides, it doubles as a reference that they can turn to for years to come.
“It's going to be able to serve as a reference manual, as opposed to just a study guide,” Whithaus said. “You really will be able to use this book as a tool to help you do better in managing your land.”
The manual, listed at $29, is available for purchase in English at https://anrcatalog.ucanr.edu/Details.aspx?itemNo=3383 and in Spanish at https://anrcatalog.ucanr.edu/Details.aspx?itemNo=3394.
/h4>A hike in navel orangeworm pressure expected later this century due to climate change
Outsized wildfires, rising sea levels and disappearing glaciers are dramatic signs of climate change, but not the only ones. New UC Agriculture and Natural Resources research provides forewarning of a change that will be economically and environmentally costly to California – a fifth generation of navel orangeworm, the most destructive pest of almonds, walnuts and pistachios.
Navel orangeworm (NOW) will be more problematic in the future because of warming temperatures, UC Cooperative Extension scientists report in Science of the Total Environment.
Like most insects,NOW's development rate, physiology, behavior and reproduction are highly dependent on the ambient temperature. When the weather warms in the spring, NOW moths emerge from the nuts left in the tree or on the ground during the winter. After mating, females then recycle those last year's nuts to lay eggs and complete one generation. Adults emerged from that first and subsequent generations then lay eggs on in-season hull-splitalmondnuts, where larvae feeding damages the crop. Typically the pests fly three to four times per year – with more flights in areas with warmer weather.
“Warmer temperatures can result in early activity of the pests in the spring and increased activity during the season,” said Tapan Pathak, the UC Cooperative Extension climate change specialist and the study's principle investigator.
The scientists looked at 10 climate models to determine what nut farmers can expect to face over the next 80 years and applied NOW developmental models to the changing climate. Daily maximum and minimum temperature data were obtained for 1950 to 2005, and future projections stretched to 2100.
“The fifth generation can happen in the next few decades,” said Jhalendra Rijal, UC integrated pest management advisor and co-author of the research. “The climate models suggest that spring will begin earlier. That causes insect activity to start earlier. With increased temperatures through the season, the number of days to complete a generation is less. At the end of 2050 or so, we'll see an extra generation.”
The study focused on 23 counties in the Central Valley, from Shasta County in the north to Kern County in the south, where 1.78 million bearing acres of nut crops are planted. About two-thirds of that acreage is planted to almonds, 20% in walnuts and 16% in pistachios. The tree nut crops were valued at more than $8 billion combined in 2018, according to the California Department of Food and Agriculture.
The completion of the NOW life cycle is faster in pistachio compared to almonds and walnuts, so the potential risk of crop damage and economic loss is higher in pistachio, according to the research report. There are only a few years historically in which the models detected the fifth generation of NOW in Kern County pistachios. The occurrence of the fifth generation in almonds and walnuts was historically nonexistent, but it starts appearing in three southern counties by 2040 and eleven counties by 2100.
“In order to alleviate some of the risks related to navel orangeworm damage to nut crops, it is important to implement integrated pest management practices,” Pathak said.
IPM preventative and control measures include sanitizing the orchard during the winter by removing all the nuts on the ground and in the trees, applying synthetic reproductive hormones to limit the pests' ability to find mates, encouraging natural enemies, judicious of least-toxic pesticides if necessary and harvesting the crop early to avoid a new generation of the pest.
“A better understanding of future navel orangeworm pressure on California's major nut crops can help facilitate and strategize integrated pest management practices in order to minimize production risks,” Pathak said.
The results of the research can also inform growers and pest control advisers about the potential increased threat from other pests as the climate changes.
UC IPM is celebrating 40 years
The University of California Statewide Integrated Pest Management Program (UC IPM) is celebrating its 40th anniversary. Established July 1, 1979, with funding from the California Legislature, UC IPM built upon a growing movement to reduce dependence on pesticides. Drawing on expertise across the University of California system, UC IPM develops and distributes UC's best information on managing pests using safe and effective practices that protect people and the environment.
Over the years, UC IPM expanded its efforts beyond agriculture to include residential audiences such as schools, landscape and structural professionals, and public health agencies; public agencies; and natural resource managers. UC IPM works through Cooperative Extension to deliver information to clientele in every California county.
Since its inception, UC IPM delivered science-based integrated pest management (IPM) information. There's no plan to change this, but it's exciting to think about the next 40 years. Improvements in technology have changed how people learn and who they get information from. UC IPM's website and online tools need to grow and change as our users change the way they like to get information. And some of these changes will be mandatory as our funding sources have changed as well.
Some things haven't changed like the IPM advisors and affiliated advisors solving problems and providing local, practical, trusted pest management information. Over the last 40 years, pest management successes happened in both agriculture and communities.
- UC IPM and Cooperative Extension advisors joined a multi-government and grape industry team to develop and extend a low-impact pest management program for European grapevine moth and conduct research to inform regulatory policy. In 2016, European grapevine moth was declared eradicated.
- UC IPM and the UC Master Gardener Program are key partners in assisting the general public with pest issues around the home and garden. UC IPM trains more than 600 UC Master Gardener volunteers each year on topics ranging from pest identification to understanding home-use pesticides.
- UC IPM partnered with stormwater agencies and state regulators to train IPM Advocates. IPM Advocates work as consultants to help retail stores provide information about less toxic products and the safe use of pesticides. Surveys after the IPM Advocates program indicated that 76% of participating stores used the UC IPM website for identifying pests or solving problems, more than 70% increased shelf space for green or less-toxic pest management products, and more than 76% increased sales of green products.
- UCIPMandCooperativeExtensionadvisors worked together with commodity boards and the United States Department of Agriculture (USDA) to develop a successful mating disruption program to prevent codling moth damage in pears without pesticides. In 2009, 95% of California pear acreage used pheromone mating disruption, eliminating the need for codling moth pesticide sprays.
UC IPM has dedicated program staff at the UC Agriculture and Natural Resources (ANR) headquarters in Davis. The staff provides IPM leadership, training, content development, and is the magical information technology (IT) presence behind UC IPM's website and online tools. UC IPM is also the home of the Pesticide Safety and Education Program (PSEP) in California, which trains pesticide safety trainers to teach pesticide applicators, pesticide handlers, and fieldworkers safe practices.
UC IPM will continue conducting research to solve important pest problems, extending IPM programs to practitioners, providing training, and developing outreach material. Over UC IPM's next 40 years, be on the lookout for changes for the better. Changes that engage users by using new technology, adapt UC IPM's existing knowledge into easy to use decision-making tools, and facilitate the development of new products—products that Californians seeking pest solutions can use to safely and effectively solve their pest problems.