The Case for Using Certified Organic Seeds in “Sustainable” Crop Production
Sometimes I hear the comment that it is more sustainable to just go down to your local feed store and purchase seed than to order organic seed from other areas of the country and have it shipped. It is certainly cheaper to do this. Certified organic seed not only costs more than conventionally grown, but there are few sources of organic seed in Alabama, especially for cover crop seed and other bulk amounts. This means that the grower must not only pay more for the seed, but must also pay freight for having it shipped which is often as much or more than the price of the seed.
An organic grower is required to use organic seed if it is available, if not, then the grower must document at least 3 different attempts to buy organic seed. Growers who are not certified are free to use whatever seed they choose, but before you buy, make sure the seed is not treated.
Most treated seed is dyed for easy recognition and prevention of ingestion by humans and wildlife. So, if your seed is pink, it has been treated with chemicals, usually fungicides to keep the seed from rotting in wet soil. When using untreated seed, just make sure the soil is warm enough for germination to occur. Some seed are treated with systemic insecticides. These pesticides are taken up by the plant as it grows and are transported throughout the plant body, into the leaves, pollen, flowers, and fruit, meaning that the consumer is dosed as well as any insect that lands on the plant. Some, like those discussed below, are known to be toxic to honeybees and other pollinators.
Clothianidin is an insecticide developed by Takeda Chemical Industries and Bayer AG. It is in a class of compounds called neonicotinoids because they are similar to the naturally occurring chemical, nicotine. Clothianidin is absorbed by plants and then released in pollen and nectar to kill pests. It is highly toxic to bees. This chemical is commonly used to treat corn and canola seed. As bees forage on the canola flowers they become poisoned and take the poisoned pollen back to the hives, poisoning the whole colony. Though corn is wind pollinated, bees become poisoned by landing and resting on the leaves which have been contaminated from water transpired by the plant. Germany banned the pesticide after an incident in 2008 in which clothianidin was widely used as a corn seed treatment to control rootworm. Shortly after the seed was planted, 330 million bees abruptly died. Research determined that the dead bees were contaminated with clothianidin. The German government and Bayer CropScience compensated the beekeepers. France, Italy, and Slovenia also banned the chemical.
Clothianidin was first given conditional registration for use as a pesticide by the United States Environmental Protection Agency in April of 2003[1], pending the completion of additional study of its safety to be done by December of 2004 (later extended to May of 2005). The study wasn't completed until August of 2007. Clothianidin was granted an unconditional registration for use as a seed treatment for corn and canola on April 22, 2010.[2] However, in November 2010 after a review of the studies supplied by the manufacturer (Bayer), the EPA released a memo in which they stated that the studies were flawed.
The mode of action of neonicotinoids is similar to the natural insecticide nicotine, which acts on the central nervous system.[1] In insects, neonicotinoids cause paralysis which leads to death, often within a few hours. However, they are much less toxic to mammals and under the WHO / EPA classification these compounds are placed toxicity class II or class III. Because the neonicotinoids block a specific neural pathway that is more abundant in insects than warm-blooded animals, these insecticides are selectively more toxic to insects than mammals. As a group, they are effective against sucking insects, but also chewing insects such as beetles and some Lepidoptera, particularly cutworms. All neonicotinoid products are classified as general use and have been registered under EPA's Conventional Reduced Risk Program due to their favorable toxicological profiles.
Acetamiprid is for use against sucking insects, such as aphids and whiteflies, on leafy vegetables, cole crops, citrus, cotton, ornamentals, and fruiting vegetables. Ready-to-use formulations are available in addition to wettable powders and water-dispersible granules.
Clothianidin was registered in 2003 by Bayer initially for corn and canola seed treatment use. Additional approved sites include grapes, pome fruit, rice, tobacco, and turf and ornamentals.
Imidacloprid was first registered for use in the U.S. in 1992 and is possibly the most widely used insecticide of the group. It has a wide range of target pests and sites, including soil, seed, structural, pets, and foliar treatments in cotton, rice, cereals, peanuts, potatoes, vegetables, pome fruits, pecans, and turf. It is a systemic with long residual activity and particularly effective against sucking insects, soil insects, whiteflies, termites, turf insects, and Colorado potato beetle. Products are available in dusts, granules, seed dressings as flowable slurry concentrates, soluble concentrates, suspension concentrates, and wettable powders. The application rates for neonicotinoid insecticides are much lower than older, traditionally used insecticides.
The most available toxicity data of the neonicotinoids is with imidacloprid. These data indicate that it is less toxic when absorbed by the skin or when inhaled compared to ingestion. It causes minor eye reddening, but is non-irritating to the skin. Signs of toxicity in rats include lethargy, respiratory disturbances, decreased movement, staggering gait, occasional trembling, and spasms. There are no accounts of human poisoning, but signs and symptoms of poisoning would be expected to be those similar for rats. A chronic toxicity study showed that rats fed up to 1,800 ppm resulted in a No Observable Effect Level (NOEL) of 100 ppm. The EPA categorizes imidacloprid as a “Group E” (no evidence of carcinogenicity). In animals and humans, imidacloprid is quickly and almost completely absorbed from the gastrointestinal tract, and eliminated via urine and feces within 48 hours. Of the neonicotinoids, imidacloprid is the most toxic to birds and fish. Both imidacloprid and thiamethoxam are highly toxic to honeybees. Mammalian toxicities for neonicotinoid pesticides registered in Florida are shown in Table 1. Table 2 lists the toxicities to wildlife by the common name of the neonicotinoid pesticide. Table 3 provides a cross listing of many of the trade names that these products are registered and sold by in Florida.
Note: Clothianidan is also highly toxic to bees.
From the EPA:
The fate and disposition of clothianidin in the environment suggest a compound that is a systemic insecticide that is persistent and mobile, stable to hydrolysis, and has potential to leach to ground water, as well as runoff to surface waters.
Clothianidin is highly toxic to honey bees on an acute contact basis (LD50
> 0.0439 µg/bee). It has the potential for toxic chronic exposure to honey bees, as well as other nontarget pollinators, through the translocation of clothianidin residues in nectar and pollen. In honey bees, the effects of this toxic chronic exposure may include lethal and/or sub-lethal effects in the larvae and reproductive effects in the queen.
This product is toxic to aquatic invertebrates. Clothianidin has properties and characteristics associated with chemicals detected in ground water. Contain any product spills or equipment leaks and dispose of wastes according to disposal instructions on this label. Do not contaminate water when disposing of equipment washwaters.
For updates on the efforts of beekeepers to have these pesticides banned, visit:
http://www.beyondpesticides.org/dailynewsblog/?cat=157
(Beyond Pesticides, January 11, 2012) On January 10, beekeepers from across the country gathered at a national conference, with environmental organizations at their side, to draw attention to the growing plight facing their industry –the decline of honey bees, a problem that has far reaching implications for the U.S. economy. The disappearance of the bees [...]
Posted in Agriculture, Clothianidin, Imidacloprid, Pollinators, Thiamethoxam | No Comments »
References:
1. http://edis.ifas.ufl.edu/pi117#TABLE_1
2. http://en.wikipedia.org/wiki/Neonicotinoid
3. http://www.epa.gov/opprd001/factsheets/clothianidin.pdf
4. http://www.beyondpesticides.org/dailynewsblog/?cat=157
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