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2005-01-22 | |
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Demise Of Organophosphate Insecticides Spurs Development Of
Environmentally Friendly Alternatives
Since World War II, organophosphate chemicals have
provided an inexpensive, easy-to-use and effective method for
controlling insect pests on the farm, in the home and garden, and
even on household pets.
But these insecticides are also toxic to many nontarget species,
including humans and wildlife, and their uses are being severely
curtailed as the result of a major overhaul of federal pesticide
regulations triggered by the Food Quality Protection Act of 1996. As
of 2002, 42 of 49 organophosphate products that were registered in
1996 had been either cancelled or their uses significantly
curtailed.
Fortunately, the demise of organophosphate insecticides --
including well-known products like diazinon, chlorpyrifos and
malathion -- has resulted in a trend toward less-toxic and more
environmentally friendly insect control on California farms. This
includes innovative and technologically advanced methods such as the
use of pheromones to disrupt insect mating, "biological control" of
nonnative pest insects using their natural enemies, and applications
of less-toxic and more insect-specific alternative pesticides.
In a special 48-page issue of the University of California's (UC)
peer-reviewed California Agriculture journal (January-March 2005),
scientists explore the range of alternatives to organophosphates
currently available and look to the future. The current issue of
California Agriculture, including PDF versions of all peer-reviewed
research articles, can be viewed in full online at: http://californiaagriculture.ucop.edu/0501JFM/toc.html
One classic example of biological control -- using natural
enemies to keep insect pests in check -- is the introduction of the
vedalia beetle in 1889 (sic) to control cottony cushion scale, which
was a major citrus pest at that time. The vedalia beetle has been so
successful in controlling cottony cushion scale that it is now
virtually taken for granted by growers.
The same is true of many other successful biological control
agents. "Growers are naturally concerned with pests that are causing
crop damage, and are often unaware of those pests that are present
in the crop system but held in check by the continued success of
introduced biological control agents," write Nicholas Mills and Kent
Daane, co-directors of the Center for Biological Control at UC
Berkeley.
The special issue of California Agriculture discusses numerous
successful alternatives to organophosphates, including:
* The use of pheromones -- chemicals secreted by insects for
communication -- to disrupt insect mating and thereby reduce
populations. Important successes to date include the control of
codling moth in pome fruit, oriental fruit moth in peaches and
nectarines, tomato pinworm in vegetables, pink bollworm in cotton
and omnivorous leafroller in vineyards.
* Cultural controls that make the crop less palatable to pest
insects, such as improved field sanitation, targeted planting dates,
crop rotations, and improved irrigation and fertilization schedules.
Successful examples include reducing dust in orchards to prevent the
buildup of spider mites, and the cleanup of unharvested grapes to
limit overwintering pests.
* Less toxic, more pest-specific alternative insecticides, such
as pyrethroids, neonicotinoids, insect growth regulators and other
novel chemistries. While these products also have drawbacks -- such
as toxicity to nontarget organisms, or the development of pest
resistance or secondary pest outbreaks -- they are significantly
less toxic than organophosphates.
The special issue of California Agriculture also explores novel
strategies such as microorganisms (including widely used Bacillus
thuringiensis), beneficial nematodes, petroleum oils and particle
films, genetically modified plants, and "natural" products well
known to organic growers (including sulfur, pyrethrum, and neem
oil). These occupy a small but important niche in insect control for
California agriculture.
"The elimination of the uses of many broad-spectrum pesticides
has resulted in the development and registration of numerous
reduced-risk products, as well as alternative pest- control
strategies," said Robert Van Steenwyk, UC Berkeley entomologist with
and co-chair of the special California Agriculture issue.
"University researchers have been at the vanguard of this change,
and in providing cost-effective new methods and technologies that
growers can use."
Editor's Note: The original news release can be found here.
This story has been adapted from a news release issued by
University Of California, Division Of Agriculture And Natural
Resources.
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