- Author: Kathy Keatley Garvey
See UC Davis News Story
DAVIS--When entomologist James R. Carey accepted a faculty position at the University of California, Davis in March of 1980, little did he know that something would happen three months later that would frame his life’s work.
In early June, multiple Mediterranean fruit fly outbreaks clobbered California.
Then more. And more.
The Mediterranean fruit fly, the world’s worst agricultural pest, proved relentless. But so is James R. Carey.
Over the next three decades, Carey observed a prevailing pattern: outbreaks, quarantines, assorted control methods, and finally “eradication” announcements. Agricultural agencies blamed the reoccurring outbreaks on travelers and cargo bringing in infested fruit.
“Wait,” Carey said. “Let’s look at the science.”
Why, he asked, were many of the outbreaks occurring at the exact same locations year after year and with the same genetics? Serendipity? No. “The Medfly is established in California,” he argued.
The issue challenged, controlled and consumed him, from his classroom to seminars to research publications to professional gatherings. An article in Science magazine called him “the relentless voice of dissent.” Some tagged him as “passionate”; others, “courageous.” The opposition warned that his views would adversely affect U.S. agricultural exports and sought to censor him.
The peer-reviewed, data-intensive, described as “the most rigorous analysis ever on the fruit fly invasion in California,” examines the large-scale cryptic invasion of tropical fruit flies in California, totaling 17 different species. It concludes that at least five—and probably more--are permanent residents of state and cannot be eradicated.
The paper, “From a Trickle to Flood: The Large-Scale, Cryptic Invasion of California by Tropical Fruit Flies,” is the work of Carey, his former postdoctoral fellow and visiting professor Nikos Papadopoulos, and UC Davis emeritus professor Richard Plant of plant sciences and biological and agricultural engineering.
Carey dedicated the research paper to former UC Davis chancellor Theodore “Ted” Hullar (1987-1994), among the first to believe in him and “the science.”
All along, Carey asked that hard science, not politics, drive the issue.
“Many of my colleagues at the U.S. Department of Agriculture (USDA) and the California Department of Food and Agriculture (CDFA) secretly agreed with me, but publicly they would not, could not,” he said.
“The Medfly history paper is highly relevant to ongoing problems in invasion biology such as control of the apple moth, but it has broader application to science on the value of universities in both fostering research on alternative ideas and in protecting scientists who raise a dissenting voice,” commented distinguished professor Bruce Hammock, who holds a joint appointment with the UC Davis Department of Entomology and Nematology and the UC Davis Comprehensive Cancer Center. “At the time of the Medfly crisis, Dr. Carey was exploring a novel approach to studying insect populations. This approach allowed Jim and later his colleagues, including Richard Plant, Nikos Papadopoulos, and Richard Rice, to see aspects of the problem that were over looked by others.’
“Jim Carey showed extraordinary courage in speaking out against eradication procedures that had great political inertia at the time,” Hammock said. “Based on his data, the announcements of eradication were scientifically flawed and doomed to failure. Sometimes in translation of science, even with the best of intentions, one view becomes so dominant that it steamrolls over dissenting opinions and new data.”
Hammock praised Carey's “courage in raising such an alternative view and the university's protection of him in raising this view. His work has placed the study of invasion biology on a better theoretical basis.”
A respected entomologist, Carey is a fellow of the American Association for the Advancement of Science, the Gerontological Society of America, the California Academy of Science, and the Entomological Society of America. He served on the California Department of Food and Agriculture's Medfly Scientific Advisory Panel from 1987-1994, testified on the Medfly crisis to the California State Legislature in 1990, and authored the paper "Establishment of the Mediterranean Fruit Fly in California" (1991 edition of Science). He is also the former chair of the UC Systemwide Committee on Research Policy.
In addition to his invasion biology research, Carey is a world-renowned authority on aging and longevity, directing a multimillion, multi-institutional program funded by the National Institutes of Health.
“Part of my research is to keep the Medflies alive as long as possible, and the other part is to kill them,” he quipped. "I tell my wife, Patty, that I suffer from a rare professional condition known as Medfly whiplash."
Contemplating the fruit fly invasion, Carey says: “The fruit fly invasion started like cancer, with a tiny tumor enlarging into a mass and then metastasizing. In California, the first fruit fly was detected in 1954. Today more than 11,386 fruit flies have been found at some 3,348 locations in 330 cities. That’s three out of every four cities.”
Carey traces his interest in Medflies to his early teachings at UC Davis “The Medfly was in the news so much, that in my insect ecology classes, I used Medfly examples of demography instruction. This turned into handouts and then a major manuscript.
In 1987, he accepted an invitation from CDFA to join the Medfly Scientific Advisory Panel. “After the first meeting in Los Angeles, I felt something was wrong with the stock explanation that these were being reintroduced,” Carey recalled.
In 1989 Carey and colleague Richard Rice (now deceased) testified before the California State Legislature on the Medfly issue. “We were grilled,” he said. “I told them what I had been telling my fellow panel members for nearly three years behind closed doors—that the Medfly was established. I had mapped out all the finds from the beginning on large maps and overlay paper.”
After he sounded the clarion call, the opposition targeted him. “I thought I was putting my career at great risk,” Carey recalled.
In 1991, his article in Science on the establishment of the Medfly in California “caused a huge uproar and resulted in a blue ribbon panel and 13 submitted letters to the editor, including one from the CDFA director. Many were running for cover except Chancellor Ted Hullar who phoned me frequently to offer his support.”
In 1994, the CDFA replaced Carey on the Scientific Advisory Panel. “They reconstituted it with entomologists who were experts on the sterile insect method,” he said. “They started the $25 million-a-year ‘preventative release’ program that continues to this day.”
In the 1990s-early 2000s, Carey focused his primary research on aging. “I received some funding from the California Citrus Research Board for basic Medfly ecology. But the lion’s share of my research funding was from the National Institutes of Health and the National Institutes on Aging.”
In 2007, the light brown apple moth (LBAM) issue drove him back to the medfly issue. CDFA announced plans to spray, to eradicate the insect, Carey recalled. “There was zero chance of eradicating LBAM as it was spread over 10,000 square miles.”
Carey says that CDFA and USDA should look at the big picture, not the individual pixels. Carey agrees that “CDFA needs to continue to respond to outbreaks as they occur, but he advocates long-term planning based on “the science” that the insects are established. This includes heightened monitoring levels for the agriculturally rich Central Valley, an economic impact study, risk management/crop insurance, cropping strategies, fly fee zones/post harvest treatments, emergency/crisis planning, genetic analysis and a National Fruit Fly Program.
“Inasmuch as the Mediterranean, Mexican, Oriental, melon, guava and peach fruit flies have all been detected in the Central Valley, monitoring this incredibly important agricultural region should be increased by 5 to 10-fold in order to intervene and suppress populations and thus slow the spread,” Carey declared.
“These pests cannot be wished away or legislated out of existence. Policymakers need to come to grips with this sobering reality of multiple species permanently established in our state in order to come up with a long-term, science-based policy for protecting agriculture in our state.”
(Editor's Note: See James Carey's website for links to his work.)
- Author: Kathy Keatley Garvey
Aug. 6, 2013
(See sidebar on James Carey)
(Read PDF of research article)
DAVIS--Research published today in the highly respected international journal Proceedings of the Royal Society B clearly demonstrates that at least five and as many as nine species of tropical fruit flies, including the infamous Medfly, are permanently established in California and inexorably spreading, despite more than 30 years of intervention and nearly 300 state-sponsored eradication programs aimed at the flies.
The new study by a trio of scientists affiliated with the University of California, Davis, has significant implications for how government agencies develop policies to successfully manage pests that pose a threat to California's $43.5 billion agricultural industry.
“Despite due diligence, quick responses, and massive expenditures to prevent entry and establishment of these insects, virtually all of the fruit-fly species targeted by eradication projects have been reappearing in the same locations — several of them annually — and gradually spreading in the state,” said UC Davis entomology professor James Carey, an international authority on fruit-fly invasion biology and co-author of the study, which examined more than 60 years of state fruit-fly capture data.
“Regulatory policies as well as pest management and agricultural practices need to be revised to reflect the reality that these insects are here to stay. We need to develop long-term strategies to deal with these pests that are effective, safe for public and environmental health, and minimally burdensome to growers,” Carey said. “Fortunately, the multiple small populations of fruit flies in the state and the long lag times in the growth of these populations will give policymakers and planners time to develop a robust, science-based response.”
“This work is the most comprehensive analysis of populations of tropical fruit flies in California to date, and in any region worldwide,” said insect population biologist George Roderick, the William Muriece Hoskins professor and chair of the Division of Organisms and Environment at UC Berkeley and an expert on biological invasions who is not affiliated with the new study.
“The strength of the study lies in the use of multiple lines of evidence — population modeling, molecular genetics, ecological trapping, border control/airport detections — and that it studies the same phenomenon in 17 species,” Roderick said.
“The study has dramatic implications for California agriculture and the state’s international trading partners, and speaks to the urgent need to alter current eradication policies aimed at invasive species,” said horticultural entomologist Michael Parrella, professor and chair of the UC Davis Department of Entomology and Nematology.
Frank Zalom, incoming president of the Entomological Society of America and a UC Davis entomology professor, said the new study provides a “careful and systematic analysis of fruit-fly finds and presents a compelling argument that these detections represent continued reoccurrences of resident populations rather than re-invasions of California.”
“This study deserves serious consideration, and I hope that it helps lead to new discussions on a long-term approach for dealing with fruit flies and similar exotic pests by the United States and international regulatory authorities,” said Zalom, who is an expert on integrated pest management.
Carey notes that other U.S. states and European nations with conditions equally hospitable to fruit flies, as well as similar patterns of international travel and detections of fruit flies in cargo at ports of entry, do not have established fruit-fly populations.
“This combination of findings definitively rebuts the hypothesis that the multiple detections of many species of fruit flies in California each year are the result of repeated new introductions,” he said. “What we are detecting here are low-level, established populations.”
Carey collaborated with lead study author Nikos Papadopoulos, an entomologist at the University of Thessaly, Greece, and Richard Plant, a UC Davis professor emeritus of plant sciences and biological and agricultural engineering. Papadopoulos, the study’s lead author and an internationally renowned expert on fruit-fly demography and invasion biology, was formerly a postdoctoral fellow and visiting scholar at UC Davis.
"These findings may have wider implications regarding management of fruit-fly invasions that may go well beyond California,” Papadopoulos said. “This unique dataset can provide many fundamental answers regarding many aspects of invasion biology and related global policy.”
“We’re very confident that our results indicate that at least five and possibly several more fruit-fly species are established in California,” said Plant, who provided mathematical modeling and statistical analysis for the study.
The researchers applied computerized data-mapping technology to analyze historical fruit-fly detection data. Using this analysis, they determined that besides the olive fly, which is confirmed as established, the Mediterranean, Mexican, oriental, melon, peach and guava fruit flies are now also established in California.
Fruit-fly history in California
Tropical fruit flies have been a concern to California for nearly 60 years, with the first fruit fly discovered here in 1954. Since then, 11,386 individual flies, including adults and larvae representing 17 different fruit-fly species, have been detected in nearly all regions of the state.
Both adult and larval fruit flies pose a threat, with the larvae (maggots) actually burrowing into and damaging a wide range of fruits and vegetables.
Because of the state’s geographic location and climate, California is considered particularly vulnerable to introduction and establishment of tropical fruit-fly populations. The pests were thought to be arriving either on cargo shipments or on infested fruits carried in by travelers from regions of the world where fruit flies were native or had become established.
State and federal agencies have for many years coordinated efforts to prevent the invasive fruit flies from establishing breeding populations in California and other vulnerable states. Such activities include restricting commodity imports from regions with ongoing fruit-fly outbreaks, requiring post-harvest treatments for produce grown in areas with established fruit-fly populations, maintaining large-scale fruit-fly monitoring programs for early detection, and release of sterile fruit flies to slow or prevent reproduction of the invasive flies.
The potential costs associated with established fruit-fly populations are substantial. For example, a 1995 study estimated that a confirmed Medfly establishment alone in California would result in $493 million to $875 million in annual direct costs, and the imposition of a related embargo on shipping fruits and vegetables from the state would cause an additional loss of $564 million. The state economy could lose $1.2 billion in gross revenue and more than 14,000 jobs, the earlier study suggested.
New study findings
In the new published study, the researchers report that several lines of evidence now indicate that the fruit flies have become self-sustaining and thus established in California, including:
- abrupt initial appearance of fruit flies in the mid-1950s, followed by many repeat detections;
- seasonality of fruit-fly appearances;
- northward spread of fruit-fly detections in the state;
- lack of new detections or introductions of fruit-fly species in most other at-risk regions of the United States and the Mediterranean; and
- multiple detections of several fruit-fly species in nearly the same California locations 20 to 50 years after they were first detected.
“Collectively, the data suggest that, much like other invasive species, tropical fruit flies can be present in low numbers for decades,” Carey said. “This ‘lag time,’ which is such a hallmark of invasion biology, explains why California can be harboring very small, established populations of these pests with only periodic captures that reveal their presence.”
He noted that two aspects of the fruit-fly invasions are advantageous for policymakers and planners: all detected fruit-fly species are extremely small and may continue to exist for years below detectable levels, and the fairly long lag times provide opportunities for developing new management protocols and programs.
Suggested response
Carey said that an immediate assessment should be made of the economic impact of having each species established in the state, projecting the individual and collective effects of the fruit flies for all affected California fruit and vegetable crops.
He also suggests that government agencies might increase fruit-fly monitoring, particularly in the Central Valley and California’s other agriculturally important areas; make contingency plans for future outbreaks; establish “fruit-fly-free” zones in the state to assure trading partners; and enable farmers to purchase crop insurance that would provide protection against losses due to fruit-fly crop damage or marketing restrictions.
In addition, California farmers and packers should consider the presence of established fruit-fly populations when developing their cropping plans and production strategies, he said.
In the scientific arena, Carey recommends that genetic analyses be developed for all of the fruit-fly species identified in the state, to determine whether single or multiple invasions of each species are occurring and identify new strains that might be introduced in the future.
Invasion biology expert Roderick from UC Berkeley projects that the new study will have a sustaining impact on both science and policy.
“I predict this paper will be remembered as much for its future impact on how science is used in developing strategies for pest management worldwide as for the conclusions it draws about the state of tropical fruit-fly populations in California,” he said.
The study was supported by the Organization for Economic Co-operation and Development and internal funding from the University of California, Davis, and the Cooperative Research Program at the University of Thessaly, Greece.
About UC Davis
For more than 100 years, UC Davis has engaged in teaching, research and public service that matter to California and transform the world. Located close to the state capital, UC Davis has more than 33,000 students, more than 2,500 faculty and more than 21,000 staff, an annual research budget of nearly $750 million, a comprehensive health system and 13 specialized research centers. The university offers interdisciplinary graduate study and more than 100 undergraduate majors in four colleges — Agricultural and Environmental Sciences, Biological Sciences, Engineering, and Letters and Science. It also houses six professional schools — Education, Law, Management, Medicine, Veterinary Medicine and the Betty Irene Moore School of Nursing.
Media contact(s):
- James Carey, Entomology, (530) 752-6217, jrcarey@ucdavis.edu (Carey will be away from campus Aug. 6-10 but can be reached then by e-mail or on cell at (530) 400-8998.)
- Pat Bailey, UC Davis News Service, (530) 752-9843, pjbailey@ucdavis.edu
(Editor's Note: See James Carey's website for links to his work.)