- Author: Kathy Keatley Garvey
If you missed UC Davis distinguished professor James R. Carey's well-attended seminar on "California's Fruit Fly Invasion: A 70-Year Struggle Nears Critical Mass," it's now online on YouTube.
His seminar, which took place June 3 in Briggs Hall, UC Davis, and on Zoom, drew global interest, stretching as far as Australia.
Carey pointed out that Callfornia has "the largest agricultural industry in the United States ($55 billion), is the fifth largest worldwide supplier of agricultural produces, grows more than 200 different crops, and "most fruit crops have been attacked by multiple tephritid species."
The California Department of Food and Agriculture (CDFA) reported that the first Mediterranean fruit fly (medfly) outbreak occurred on June 5, 1980, he said, and as of June 3, the state has detected 18 total species of fruit flies in 350 cities, amounting to 11,000 detections.
In his hour-long seminar, Carey presented an overview of the long-developing crisis, discussed lessons learned from analysis of fruit fly detection databases, and argued that "in order to have any chance at stemming this ever-rising tide, CDFA and the USDA urgently need to switch from their historic, ad hoc eradication strategy to a new one that is evidence-based and far more scientific."
In the closing moments, he asked "Why have oriental fruit fly outbreaks been occurring annually for the past 60 years in California?"
Because, he said, the fruit flies are "permanently established."
Carey, a 44-year member of the UC Davis faculty who is retiring in June, and a senior scholar in the Center for the Economics and Demography of Aging at UC Berkeley, researches insect biodemography, mortality dynamics, and insect invasion biology. He holds a doctorate in entomology from UC Berkeley (1980).
Carey served on the CDFA's Medfly Scientific Advisory Panel from 1987-1994, testified to the California Legislature "Committee of the Whole" in 1990 on the Medfly Crisis in California, and authored the paper "Establishment of the Mediterranean Fruit Fly in California" (1991, Science 258, 457).
He is a fellow of four professional societies: Entomological Society of America, the American Association for the Advancement of Science, the California Academy of Sciences, and the Gerontological Society of America. He is former director (2003-13) of a 11-university consortium funded by the National Institute on Aging (NIH/P01) on the evolutionary ecology of lifespan. He co-authored the book “Biodemography: An Introduction to Concepts and Methods” (Carey, J. R. and D. Roach. 2020; Princeton University Press) and authored the books, “Demography for Biologists (Oxford University Press 1993), Longevity (Princeton University Press, 2003), and Longevity Records: Life Spans of Mammals, Birds, Amphibians and Reptiles (Odense, 2000) as well as more than 250 journal articles and book chapters.
- Author: Lauren Fordyce
Healthy Soils Week (Dec. 4-8) is a week-long initiative by the California Department of Food and Agriculture (CDFA) to highlight the importance of soil health throughout California.
Healthy soils can improve crop yields, sequester carbon, reduce erosion, and increase biodiversity. In addition, they can reduce pest problems and pesticide and fertilizer use. Healthy soils lead to healthy plants which are less susceptible to pest attacks and can better tolerate and recover from pest pressure.
In integrated pest management (IPM) we promote the use of cultural control methods to improve soil and plant health, making an environment less conducive for pests to establish, reproduce, and cause damage.
Here are some cultural tips for creating healthy soils and reducing pests:
- Improve soil drainage to avoid oversaturated, water-logged soils. Moist, compacted soils can attract earwigs, slugs, and nematodes and encourage damping off, Phytophthora, and other diseases to develop.
- Use mulch. Mulches can moderate soil moisture and temperature, reduce compaction, and suppress weeds. But use them carefully as improperly selected or applied mulches can damage plants and attract pests.
- Clean up fallen fruit and leaves. Good sanitation is essential for preventing pests from establishing and spreading. Removing infected fruit, leaves, and branches can prevent insects and pathogens from overwintering in the soil.
- Fertilize appropriately. Too much or not enough nutrients in the soil can result in plant stress. Stressed plants are more susceptible to pests and diseases. Applying too much fertilizer (especially nitrogen) can result in excessive plant growth which often attracts pests like aphids and psyllids.
- Dethatch lawns. Thatch includes pieces of grass stems, roots, and rhizomes. It is slow to decay and can build up on the soil surface making it difficult for water to reach the roots. Several turfgrass pathogens can also survive in thatch.
- Solarize the soil as needed. Soil solarization uses heat from the sun to kill pathogens, nematodes, and weed seeds in the soil.
Healthy soil is the foundation of sustainable pest management and a thriving ecosystem.
Seven invasive fruit fly quarantines are in place throughout California. If you live within one of these quarantine zones, fruits and vegetables should not be moved off the property they were grown on. Quarantines are in place for the Mediterranean fruit fly, Oriental fruit fly, tau fruit fly, and Queensland fruit fly. Smuggled, illegally imported fruit is the most common pathway of fruit fly entry into California.
These fruit flies lay their eggs under the skin of many crops, making their detection difficult. Females of some species can lay 1,000 eggs in their lifetime. Once eggs hatch, larvae (maggots) feed on the inside of the fruit. Infested fruit drops to the ground where larvae leave the fruit to burrow into the soil to pupate. Numerous generations can occur each year.
Invasive fruit flies pose a major threat to California agriculture as they make fruit unfit for human consumption and damage a wide variety of crops from fruits to vegetables. In addition, they pose an economic burden to commercial growers in quarantine zones as they must treat all host fruit with an approved pesticide before sale or movement within or outside of the quarantine area. You can help prevent the spread of these invasive pests and reduce the risks they pose to commercial fruit and vegetable producers by not moving homegrown produce and cleaning up and disposing of dropped fruit.
Quarantine zones include:
Mediterranean fruit fly
- Los Angeles County, Leimert Park Area
Oriental fruit fly
- San Bernardino and Riverside Counties, Redlands, Yucaipa, Highland, San Bernardino, and Riverside Areas
- Sacramento County, Rancho Cordova Area
- Contra Costa County, Brentwood Area
- Santa Clara County, Santa Clara Area
Tau fly
- Los Angeles County, Stevenson Ranch, Valencia, Santa Clarita Areas
Queensland fruit fly
- Ventura and Los Angeles Counties, Thousand Oaks Area
Quarantine zones updated December 5, 2023. To view the most up-to-date quarantine maps, visit the CDFA webpage at https://www.cdfa.ca.gov/plant/pe/InteriorExclusion/quarantine.html.
If you live in a fruit fly quarantine zone:
- Do not take fresh fruits and vegetables off your property. Don't share with neighbors or ship to friends and family in other counties or states.
- Consume or process (i.e., juice, freeze, or cook) all fruits and vegetables where they are grown.
- Dispose of homegrown fruits and vegetables by double-bagging and sealing then placing them in the trash–not in your green waste or compost bin.
Suspect you have an invasive fruit fly infestation? Contact the California Department of Food and Agriculture (CDFA) Pest Hotline: 1-800-491-1899 or your County Agricultural Commissioner. Allow authorized CDFA workers access to your property to inspect fruit, set traps, or conduct fruit fly eradication activities. Your cooperation helps protect California agriculture!
While the holiday season is a time of giving, we urge you to not share these invasive fruit flies!
[Revised from this California Dept. of Food and Agriculture (CDFA) blog post.]
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- Author: Michael Hsu
QFF quarantine in LA, Ventura counties among seven fruit fly quarantines statewide
Residents in multiple Southern California and Northern California counties should not move homegrown fruits and vegetables from their properties to help contain several species of fruit fly that can destroy crops and impact the livelihoods of local farmers.
With sharing and gifting of food integral to the holiday season, the California Department of Food and Agriculture is reminding people to heed the seven active fruit fly quarantines aimed at controlling the Mediterranean fruit fly, Oriental fruit fly, Tau fly and Queensland fruit fly. The links below describe quarantine zone boundaries:
- Mediterranean fruit fly: Los Angeles County, Leimert Park Area
- Oriental fruit fly: San Bernardino and Riverside Counties, Redlands and Yucaipa Areas
- Oriental fruit fly: Sacramento County, Rancho Cordova Area
- Oriental fruit fly: Contra Costa County, Brentwood Area
- Oriental fruit fly: Santa Clara County, Santa Clara Area
- Tau fly: Los Angeles County – Stevenson Ranch, Valencia, Santa Clarita Areas
- Queensland fruit fly: Ventura and Los Angeles Counties, Thousand Oaks Area
People within these zones should consume or process (i.e., juice, freeze or cook) their homegrown fruits and vegetables at the place of origin and not move them off their property. Uneaten produce should be double-bagged in plastic bags and disposed of in the landfill bin – not compost or green waste.
Queensland fruit fly threatens California citrus, other crops
The Queensland fruit fly (Bactrocera tryoni) quarantine is the first of its kind in the U.S. Although QFF was first seen in California in 1985, the recent detection of two adult males triggered the unprecedented quarantine action by USDA's Animal and Plant Health Inspection Service and CDFA.
“This pest has earned a bad reputation for wreaking havoc on fruit production in Australia, where it is native,” said Hamutahl Cohen, University of California Cooperative Extension entomology advisor for Ventura County. “Adult flies lay their eggs in fruit, and the eggs hatch into larvae that then feed on the fruit, causing damage.”
And while females of other fruit fly species live for only two or three months, QFF females are unique in that they can live up to a year, according to Cohen.
“Once QFF populations take root, they're challenging to manage because females can each lay up to 100 eggs per day,” Cohen said.
In addition to being highly adaptable to a variety of environmental conditions, QFF has more than 170 host plants – including a wide range of California commodities such as citrus, grape, strawberry, fig, avocado, apricot, peach, cherry, nectarine, plum, pear, apple, tomato and sweet pepper.
The threat to citrus is especially concerning, as Southern California growers continue to grapple with the specter of spreading huanglongbing (HLB) disease, which kills citrus trees. Cohen said residents of citrus-growing regions can do their part to help their neighbors and local economy by respecting quarantine restrictions.
“Growers are already dealing with other invasive species like Asian citrus psyllid [vector of HLB pathogen], so we as homeowners need to prevent the spread of fruit flies to reduce the burden on them,” she explained.
While a spike this year in the detections of multiple fruit fly species was likely caused by a host of factors, Cohen speculates that increased post-pandemic travel is helping to move the flies. And with holiday travel in full swing, she said it's important to practice “Don't Pack a Pest” principles.
“Invasive species often hitchhike on fruits and vegetables brought into California by travelers – that's why we often first find invasive species in urban and suburban backyards, and not on farms,” Cohen said. “Travelers entering the U.S. can visit dontpackapest.com to learn about which products they can and cannot bring back with them.”
To report a suspected infestation of fruit fly larvae in homegrown produce, call the CDFA pest hotline at 1-800-491-1899. Growers with questions and concerns are urged to contact their local agricultural commissioner's office.
/h3>/h3>- Author: Michael Hsu
QFF quarantine in LA, Ventura counties among seven fruit fly quarantines statewide
Residents in multiple Southern California and Northern California counties should not move homegrown fruits and vegetables from their properties to help contain several species of fruit fly that can destroy crops and impact the livelihoods of local farmers.
With sharing and gifting of food integral to the holiday season, the California Department of Food and Agriculture is reminding people to heed the seven active fruit fly quarantines aimed at controlling the Mediterranean fruit fly, Oriental fruit fly, Tau fly and Queensland fruit fly. The links below describe quarantine zone boundaries:
- Mediterranean fruit fly: Los Angeles County, Leimert Park Area
- Oriental fruit fly: San Bernardino and Riverside Counties, Redlands and Yucaipa Areas
- Oriental fruit fly: Sacramento County, Rancho Cordova Area
- Oriental fruit fly: Contra Costa County, Brentwood Area
- Oriental fruit fly: Santa Clara County, Santa Clara Area
- Tau fly: Los Angeles County – Stevenson Ranch, Valencia, Santa Clarita Areas
- Queensland fruit fly: Ventura and Los Angeles Counties, Thousand Oaks Area
People within these zones should consume or process (i.e., juice, freeze or cook) their homegrown fruits and vegetables at the place of origin and not move them off their property. Uneaten produce should be double-bagged in plastic bags and disposed of in the landfill bin – not compost or green waste.
Queensland fruit fly threatens California citrus, other crops
The Queensland fruit fly (Bactrocera tryoni) quarantine is the first of its kind in the U.S. Although QFF was first seen in California in 1985, the recent detection of two adult males triggered the unprecedented quarantine action by USDA's Animal and Plant Health Inspection Service and CDFA.
“This pest has earned a bad reputation for wreaking havoc on fruit production in Australia, where it is native,” said Hamutahl Cohen, University of California Cooperative Extension entomology advisor for Ventura County. “Adult flies lay their eggs in fruit, and the eggs hatch into larvae that then feed on the fruit, causing damage.”
And while females of other fruit fly species live for only two or three months, QFF females are unique in that they can live up to a year, according to Cohen.
“Once QFF populations take root, they're challenging to manage because females can each lay up to 100 eggs per day,” Cohen said.
In addition to being highly adaptable to a variety of environmental conditions, QFF has more than 170 host plants – including a wide range of California commodities such as citrus, grape, strawberry, fig, avocado, apricot, peach, cherry, nectarine, plum, pear, apple, tomato and sweet pepper.
The threat to citrus is especially concerning, as Southern California growers continue to grapple with the specter of spreading huanglongbing (HLB) disease, which kills citrus trees. Cohen said residents of citrus-growing regions can do their part to help their neighbors and local economy by respecting quarantine restrictions.
“Growers are already dealing with other invasive species like Asian citrus psyllid [vector of HLB pathogen], so we as homeowners need to prevent the spread of fruit flies to reduce the burden on them,” she explained.
While a spike this year in the detections of multiple fruit fly species was likely caused by a host of factors, Cohen speculates that increased post-pandemic travel is helping to move the flies. And with holiday travel in full swing, she said it's important to practice “Don't Pack a Pest” principles.
“Invasive species often hitchhike on fruits and vegetables brought into California by travelers – that's why we often first find invasive species in urban and suburban backyards, and not on farms,” Cohen said. “Travelers entering the U.S. can visit dontpackapest.com to learn about which products they can and cannot bring back with them.”
To report a suspected infestation of fruit fly larvae in homegrown produce, call the CDFA pest hotline at 1-800-491-1899. Growers with questions and concerns are urged to contact their local agricultural commissioner's office.
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