Medfly spraying
Medfly spraying refers to the aerial application of pesticides to control infestations of the Mediterranean fruit fly (Ceratitis capitata), a significant agricultural pest that threatens over 250 types of fruits and vegetables. Native to tropical regions, the Medfly has attempted to establish itself in the continental United States multiple times since its first appearance in Florida in 1929. The female Medfly lays eggs in the flesh of fruits, leading to larval development that damages crops and renders them inedible. As a response to the threat posed by this fly, various eradication methods have been employed, with aerial spraying of pesticides like malathion being one of the most common approaches. However, this method is controversial due to concerns over its potential harmful effects on non-target insects, wildlife, and human health, prompting regulatory scrutiny from the Environmental Protection Agency (EPA).
In light of these concerns, alternative strategies have emerged, including the release of sterilized male flies to disrupt the breeding cycle and the use of dye-based pesticides that target Medflies while minimizing environmental impact. Recent outbreaks in California have led to renewed quarantine measures and the implementation of these innovative control methods. Overall, while Medfly spraying is seen as a necessary tactic to protect agricultural produce, it continues to evoke a range of opinions regarding its environmental and health implications.
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Medfly spraying
DEFINITION: Aerial application of pesticides to eliminate the Mediterranean fruit fly, an agricultural threat
Efforts to eradicate Medfly infestations through the spraying of pesticides have met with criticism by many environmentalists because of concerns about the possible harmful effects of the pesticides on other insects, wildlife, livestock, aquaculture, water supplies, and human health.
The small, two-winged Mediterranean fruit fly, or Medfly (Ceratitis capitata), belongs to a group of insects commonly called fruit flies. Considered a major agricultural around the world, the Medfly is a threat to more than 250 vegetables and fruits, including peaches, cherries, avocados, pears, and citrus fruits. A longtime inhabitant of Hawaii and the Tropics, the Medfly has repeatedly tried to establish itself in the continental United States since its first unsuccessful foray into Florida in 1929. Attempts to control the fly with pesticides have so far proven successful but controversial.
The incompatibility of the Medfly with humans stems from the insect’s fondness for domestic crops. Typically, the female fly lays eggs—as many as several hundred at a time—in the fleshy parts of fruits or vegetables. When the eggs hatch, the larvae tunnel through the fruit, making it unfit for human consumption. When the damaged fruit falls to the ground, the larvae exit and burrow into the ground until they mature into flies and start the cycle over again.
Because of the Medfly’s capacity for causing widespread crop destruction, governments around the world have imposed various quarantines, embargoes, and postharvest treatment requirements on any fruits and vegetables that originate in areas known to be infested with the insect. Various eradication programs were used against the Medfly in the United States during the twentieth century. Early efforts in Florida included the use of a compound of arsenate and copper carbonate that was applied with handheld equipment. Another control method was the removal of infested fruit trees.
Prior to the twenty-first century, the most common form of eradication practiced was the aerial spraying of the malathion mixed with a bait, such as syrup. A poison also employed to control mosquitoes, malathion is used in weaker amounts in the war against the Medfly. Although all aerial spraying attempts in the United States must receive prior approval from the Environmental Protection Agency (EPA), the use of malathion generated controversy in California and Florida. Opponents commonly complain about the pesticide’s possible harmful effects on other insects, wildlife, livestock, aquaculture, water supplies, and human health—especially that of children. In response to these concerns, the EPA requires various federal and state agencies involved in eradication programs to seek more environmentally friendly methods to battle the Medfly.
One alternative to the spraying of malathion involves the use of domestically raised flies that have been sterilized through radiation; these flies are released to mate unsuccessfully with wild Medflies, thus reducing the regenerative capacity of the population. Another method that has been used involves a pesticide made from a mixture of two dyes, phloxine B and uranine, which are commonly used to tint drugs and cosmetics. Once ingested by the Medfly, the dye particles absorb light, which in turn produces oxidizing agents that destroy cell tissues. As a result, most flies die within twenty-four hours. The dyes quickly lose their potency and become nontoxic. Preliminary tests of this method in Hawaii indicated that the use of these dyes were more effective and safer for the than malathion.
In 2023, the state of California detected an usually large number of medflies and other exotic, crop-harming fruit flies. In response, the state initiated quarantine measures in several counties that lasted into 2024. According to the protocol for battling medflies, the first step in fly eradication was to release sterilized male flies into the population to disrupt the breeding cycle. The flies would mate with females in the wild and produce infertile eggs. If this process did not produce the desired result, then targeted bait treatment would be used that released a protein coated with a toxin that killed adult flies. Cover spraying of the entire tree with pesticides was only recommended if the medfly infestation reached unacceptable proportions. If a breeding population took root on a property, then officials had the option of removing the fruit from within 100 meters of a detection site and disposing of it in a landfill.
Bibliography
Gullan, P. J., and P. S. Cranston. “Pest Management.” In The Insects: An Outline of Entomology. 5th ed. Hoboken, N.J.: John Wiley & Sons, 2014.
Hamilton, Denis, and Stephen Crossley, eds. Pesticide Residues in Food and Drinking Water: Human Exposure and Risks. Hoboken, N.J.: John Wiley & Sons, 2004.
"Proclamation of Emergency Program for the Mediterranean Fruit Fly." California Department of Food and Agriculture, 19 Oct. 2023, www.cdfa.ca.gov/plant/pdep/treatment/2023/20231019‗Medfly‗PEP‗LeimertPark‗LosAngelesCounty‗2023-10‗SoF.pdf. Accessed 19 July 2024.