Checking insect traps for the Asian citrus psyllid
The U.S. Environmental Protection Agency has approved the use of two antibiotics in the fight against a dreaded citrus disease, despite concerns from critics who fear it may contribute to the development of antibiotic-resistant diseases in humans.
The two drugs, streptomycin and oxytetracycline, have been used in Florida for the last several years as a last-ditch effort to try to slow the progress of citrus greening, or huanglongbing. The disease has decimated the state’s citrus industry with economic losses totaling $9.1 billion according to the University of Florida.
But scientists have found that antibiotics, known in agriculture as bactericides, can delay the spread of the deadly citrus bacteria. The disease is passed from tree to tree by a tiny winged insect called the Asian citrus psyllid.
Environmentalists, however, don’t believe the benefits outweigh the potential risks to humans.
“Citrus greening is a big deal and we understand that citrus is a huge industry,” said Nathan Donley, senior scientist with the Center for Biological Diversity. “But the widespread spraying of this without fully understanding the risk involved is really questionable.”
Donley and others do no believe the EPA has done an adequate job studying the potential harm to consumers.
The concern stems from the question over whether agricultural uses of antibiotics can contribute to the development of antibiotic resistance in humans. More and more, meat producers are labeling their products as being free of antibiotics, in response to consumer concerns.
This year, a new law took effect in California that makes it more difficult to give healthy livestock antibiotics. When he signed the legislation in 2015, Gov. Jerry Brown called the alleged overuse of antibiotics in animal agriculture “an urgent public health problem.”
Nan Wishner, board member of the California Environmental Health Initiative, said agriculture needs to look harder at developing safer alternatives to battle pests and diseases, especially as climate change may alter what crops can be grown and where.
“We need to start growing our food differently,” she said. “Farmers need to make a living and people like oranges, but we need to figure out a way to do that without using chemicals like these.”
EPA officials acknowledged in their review of antibiotics that the science of resistance is evolving and “there is a high level of uncertainty in how and when resistance occurs.” It also sought input from the Centers for Disease Control and Prevention, Food and Drug Administration and the U.S. Department of Agriculture.
In the end, the EPA approved the use, but with some restrictions
“Our federal partners expressed a number of concerns on expanding uses of antibiotics in plant agriculture. Overall, they recommend judicious use, prevention of drift to neighboring fields/water bodies and additional protection of agriculture pesticide handlers from exposure,” the EPA wrote.
Finding a solution for citrus greening has been a vexing one for scientists worldwide. What they have in their arsenal is mostly a combination of weapons to knock down the population of psyllids, including insecticides, parasitic wasps and other deterrents.
Now, the citrus industry can add bactericides to its tool box. California’s citrus leaders, who are among the nation’s major citrus suppliers, have been pushing for its approval.
Jim Adaskaveg, a plant pathologist at the University of California, Riverside, said the bactericides may be used on a limited basis in Southern California, where the citrus disease has been found in backyard citrus trees. Commercial citrus groves within a 15-mile radius of a citrus greening hot spot have the option to use the bactericides.
“We will use this as a protective treatment,” Adaskaveg said. “Hopefully we can slow down the bacterium because the disease depends on large numbers of bacteria to grow. If we can keep those bacteria numbers low, it will slow down everything.”
What California’s citrus industry is trying desperately to prevent is the disease finding its way to the San Joaquin Valley, the state’s major citrus growing region.
So far, only the bug has been found in the Valley, not the disease. But experts say that day is inevitable and they want every tool available to buy them time until they find a cure.
Research entomologist Beth Grafton-Cardwell with UC Riverside said the public should not be worried about the use of bactericides. She said they have effectively used them for years to treat bacterial diseases in pears and apples.
“It is not like we have never used these before,” she said. “And what people need to know is that these are being formulated for plants not animals and it is not going to affect us.”