Natural pest and disease control methods are getting a second look these days as more consumers turn their noses up at pesticides. Gardening existed long before synthetic pesticides, which is why these remedies go back centuries, according to The Paris Review. Gardeners know that castor bean plants guard against flies and mosquitoes, as well as rabbits and other rodents. Basil also protects against aphids, as do ladybugs, according to The Spruce.
The United States Department of Agriculture has a Biological Control Program, which they note is safe, easy to use and cost effective. What are some examples of successful biological control? Are there any downsides? Should humans intervene with natural occurrences in ecosystems?
Biological Pest Control
Harry Scott Smith, a Nebraska-born scientist, is credited with coining the term “biological control” in 1919 for natural pest and disease control, according to The Los Angeles Times. Though the term was new, it referred to the age-old practice of using natural enemies to effect pest control.
Since 1919, biological control has logged some stunning successes. Most notably, the introduction of the South American wasp in Africa in the 1980s succeeded in containing the cassava mealybug. That intervention saved approximately 20 million lives, according to Science. In 1868, the cottony-cushion scale — so named for the white, cottony secretion it produces — devastated California’s citrus industry. A scientist was dispatched to Australia, where the bug was believed to originate, and discovered the cottony scale had a natural enemy: the vedalia ladybird beetle. The 514 beetles introduced to the area dramatically reduced the cottony scale population. By 1890, the pest had been eliminated, Science reported.
Sometimes nature practices its own biological control. A scientist attempted to bring the samurai wasp — an Asia-based insect — to the U.S. to control the stinkbug population, but he realized that the wasp had already traveled to the U.S. and was in the process of targeting the stinkbug, according to the Seattle Times. Natural occurrences can occasionally eliminate the need for human intervention.
While most examples have been positive, natural pest and disease control can have its downsides. One of the most famous examples is the cane toad. Australia’s Bureau of Sugar Experiment Stations introduced the cane toad in 1935 to control the gray-backed cane beetle, but the cane toad soon became a menace and an invasive species that Australia still combats today, according to The BBC.
Genetic modification is a potential avenue for biological control. For example, Hawaii is considering genetically modifying their overwhelming population of mongoose and rodents so that they no longer reproduce, as they are currently devastating the local population of turtles and birds, per the Hawaii Tribune-Herald.
CRISPR, a gene-editing tool, makes the possibility of genetic modification for biological control tangible. In 2015 alone, malaria killed between 438,000 and 720,000 people. Scientists have used CRISPR to genetically modify mosquitoes to resist the malaria virus, which could save hundreds of thousands of lives. They hope to use the technology by 2023, according to Vox.
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