In 2015, the largest oriental fruit fly (Bactrocera dorsalis) population ever discovered in the state occurred in the middle of Florida’s tropical fruit production areas—the largest tropical fruit production area in the continental U.S.—resulting in a 99-square mile quarantine. The outbreak was successfully quelled through a six-month eradication program that combined outreach, control, science, technology, and regulation. (Image originally published in Steck et al, American Entomologist, Summer 2019)

By Trevor Smith, Ph.D., Holly Hughes, and Olivia Doyle

Fruit flies are among the most significant threats to global agriculture and are of particular concern to the state of Florida, which deals with roughly 30 new exotic arthropods and/or plant pathogens every year. In 2015, the largest oriental fruit fly (Bactrocera dorsalis) population ever discovered in the state occurred in the middle of Florida’s tropical fruit production areas—the largest tropical fruit production area in the continental U.S.—resulting in a 99-square mile quarantine.

A total of 158 adult flies were detected during the ensuing delimitation surveys and the eradication program. In one trap alone, 45 male oriental fruit flies were found on a Jackson trap. Over the course of the six-month eradication program, the Florida Department of Agriculture and Consumer Services (FDACS) Division of Plant Industry (DPI) worked alongside the United States Department of Agriculture (USDA), the FDACS Office of Agricultural Law Enforcement, and the University of Florida Institute of Food and Agricultural Sciences’s Tropical Research and Education Center to eradicate this invasive pest.

Detailed in an in-depth article in the Summer 2019 issue of American Entomologist, this collaborative effort was a combination of new, innovative, and proven methods for eradication through outreach, control, science, technology, and regulation.

In 2015, the largest oriental fruit fly (Bactrocera dorsalis) population ever discovered in the state occurred in the middle of Florida’s tropical fruit production areas. The outbreak was successfully quelled through a six-month eradication program that combined outreach, control, science, technology, and regulation. (Photo credit: Gary J. Steck, Ph.D.)

In 2015, the largest oriental fruit fly (Bactrocera dorsalis) population ever discovered in the state occurred in the middle of Florida’s tropical fruit production areas—the largest tropical fruit production area in the continental U.S.—resulting in a 99-square mile quarantine. A total of 158 adult flies were detected during the ensuing delimitation surveys and the eradication program. In one trap alone, 45 male oriental fruit flies were found on a Jackson trap. (Map by Matt Albritton, originally published in Steck et al, American Entomologist, Summer 2019)

Outreach

The 2015 oriental fruit fly eradication program implemented new public outreach methods not previously used in similar eradication programs. Partnering with other state agencies and private stakeholders played a vital role in the dissemination of program news and information.

Some of the outreach components utilized throughout the eradication program were information tents centrally located in quarantine areas, where members of the public could meet to ask questions and receive applicable information. The Division of Plant Industry also maintained an interactive website throughout the duration of the program for stakeholders to reference regularly.

Email updates were released daily, allowing industry stakeholders to receive timely answers to aid in their decision-making process. Multiple other means of communication were implemented to allow for transparency and ease of information sharing, such as a toll-free helpline and a dedicated regulatory information phone line.

In the course of the 2015-2016 oriental fruit fly eradication program in Florida, one outreach method employed by the Florida Department of Agriculture and Consumer Services was setting up information tents centrally located in quarantine areas, where members of the public could meet to ask questions and receive applicable information. (Photo credit: Abbie Fox, originally published in Steck et al, American Entomologist, Summer 2019)

Control

DPI used four control strategies to eradicate the oriental fruit fly. This included use of the male annihilation technique (MAT) using dibrom a mixture of naled (toxicant) and methyl eugenol (male attractant), GF-120 foliar treatments, Warrior II soil drenches, and fruit removal and destruction.

Each of these methods targets a different life stage or behavior of the fruit fly’s biology. Dibrom was applied to utility poles in the treatment area to attract and kill adult males. The Warrior II soil drench was applied under the drip line of B. dorsalis fruit-bearing host plants on all properties targeting third instars and pupae in the soil. The GF-120, a certified treatment for use in organic production systems, was applied to host plants to attract and kill feeding adults. And, host fruit was stripped from trees and destroyed to eliminate eggs and early instar larvae.

This was the first time Warrior II was used for soil drench in a regulatory quarantine program. At the request of the local agricultural community, an aerial bait spray application of GF-120 was made over the entire 9,850-acre treatment area. This marked the first use of an aerial treatment against invasive fruit flies in Florida since the 1999 Tampa eradication program, and the first use of GF-120 as an aerial application.

Following the largest oriental fruit fly (Bactrocera dorsalis) outbreak ever discovered in the state of Florida in 2015, a 99-square-mile quarantine zone was established. The Florida Department of Agriculture and Consumer Services’ Office of Agricultural Law Enforcement patrolled the area at all roads leading out of the quarantine area. Over six months, they confiscated approximately 75,000 kilograms of non-compliant commodities being moved in or out of the quarantine area illegally. (Map by Matt Albritton, originally published in Steck et al, American Entomologist, Summer 2019)

Science

Molecular scientists at the USDA-Animal and Plant Health Inspection Service utilized DNA sequencing to identify the fruit fly haplotype and its genetic profile, identifying it as a southeast Asian strain. Because of this information, scientists were able to determine the fruit flies in the 2018 eradication program in the same area were genetically different, verifying the success of the 2015 eradication program. Having a record of the molecular profile allows for more precise identifications and serves as a reference guide for future programs.

Technology

Technology played a key role in the success of the program. Although an expensive solution, a technology used for high-value crops such as dragon fruit and mamey sapote was irradiation. There were no facilities doing phytosanitary radiation in Florida; however, a plan was developed to allow movement of these commodities with a special permit to the nearest facility in Gulfport, Mississippi.

Interactive maps were a useful tool throughout the program as well. The technology used in the interactive maps allowed for the delivery of consistent and straightforward messages about the pest, regulations, control measures, and the quarantine area.

Regulatory

The sheer magnitude of the regulatory challenge that this program represented was absolutely unique. Requirements for growers, packinghouses, and plant nurseries in the quarantine area were implemented and enforced through compliance agreements. Site visits were performed to confirm that all regulated entities were complying with program regulations.

During the program, a total of 1,804 compliance agreements were issued including over 800 plant nurseries, 800 growers, and numerous packinghouses, fruit and produce dealers, and transporters. The FDACS Office of Agricultural Law Enforcement was responsible for enforcing compliance and patrolled the area night and day at all roads leading out of the quarantine area. They confiscated approximately 75,000 kilograms of non-compliant commodities being moved in or out of the quarantine area illegally.

A Combination for Success

Ultimately, the best response to a pest quarantine is the elimination of the agent as soon as possible. The 2015 eradication program’s success and rapid eradication was due to a well-coordinated, multi-agency program with experienced personnel and superior resources. The methods used to eradicate this fruit fly such as MAT, soil-drenching, and fruit removal led directly to the success of the program.

The total time from first detection to the last detection of B. dorsalis was 45 days. The quarantine was officially lifted on February 13, 2016, fewer than six months after it began, with a total of more than 430 FDACS employees having contributed to the eradication program.

Trevor Smith, Ph.D., is director of the Division of Plant Industry at the  Florida Department of Agriculture and Consumer Services (FDACS). Email: trevor.smith@freshfromflorida.com. Holly Hughes and Olivia Doyle are both information speicalists at FDACS. Email: holly.hughes@freshfromflorida.com and olivia.doyle@freshfromflorida.com.