Long-Term Effects of Repeated Exposure of Honey Bee Colonies to Flowering Crops Treat

Discussion in 'Bee News' started by Americasbeekeeper, Oct 30, 2013.

  1. Americasbeekeeper

    Americasbeekeeper New Member

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    A Four-Year Field Program Investigating Long-Term Effects of Repeated Exposure of Honey Bee Colonies to Flowering Crops Treated with Thiamethoxam
    Neonicotinoid residues in nectar and pollen from crop plants have been implicated as one of the potential factors causing the declines of honey bee populations. Median residues of thiamethoxam in pollen collected from honey bees after foraging on flowering seed treated maize were found to be between 1 and 7 µg/kg, median residues of the metabolite CGA322704 (clothianidin) in the pollen were between 1 and 4 µg/kg. In oilseed rape, median residues of thiamethoxam found in pollen collected from bees were between <1 and 3.5 µg/kg and in nectar from foraging bees were between 0.65 and 2.4 µg/kg. Median residues of CGA322704 in pollen and nectar in the oilseed rape trials were all below the limit of quantification (1 µg/kg). Residues in the hive were even lower in both the maize and oilseed rape trials, being at or below the level of detection of 1 µg/kg for bee bread in the hive and at or below the level of detection of 0.5 µg/kg for hive nectar, honey and royal jelly samples. The long-term risk to honey bee colonies in the field was also investigated, including the sensitive overwintering stage, from four years consecutive single treatment crop exposures to flowering maize and oilseed rape grown from thiamethoxam treated seeds at rates recommended for insect control. Throughout the study, mortality, foraging behavior, colony strength, colony weight, brood development and food storage levels were similar between treatment and control colonies. Detailed examination of brood development throughout the year demonstrated that colonies exposed to the treated crop were able to successfully overwinter and had a similar health status to the control colonies in the following spring. We conclude that these data demonstrate there is a low risk to honey bees from systemic residues in nectar and pollen following the use of thiamethoxam as a seed treatment on oilseed rape and maize.
    http://www.plosone.org/article/info:doi/10.1371/journal.pone.0077193
     
  2. Ray

    Ray Member

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    [h=2]Snip from Wikipedia:

    ​History[edit][/h]Thiamethoxam was developed by Syngenta but a patent dispute arose with Bayer which already had patents covering other neonicotinoids including imidacloprid. In 2002 the dispute was settled, with Syngenta paying Bayer $120 million in exchange for worldwide rights to thiamethoxam.[SUP][3][/SUP][SUP][4][/SUP]
    [h=2]Uses[edit][/h]Thiamethoxam is a systemic insecticide that is absorbed quickly by plants and transported to all parts of the plant, where it acts as a deterrent to insect feeding. It is active in the stomach of the insects, and also through direct contact. The compound interferes with information transfer between nerve cells, making the insects become paralyzed.
    Thiamethoxam is effective against aphids, thrips, beetles, centipedes, millipedes, sawflies,leaf miners, stem borers and termites.
    Syngenta asserts that thiamethoxam triggers various physiological reactions, which induce the expression of specific functional proteins involved in various stress defense mechanisms of the plant allowing it to better cope under tough growing conditions.[SUP][5][/SUP]
    Thiamethoxam is a moderately toxic substance. In normal use, there are no unacceptable risks involved. The substance is toxic to bees and harmful to aquatic and soil organisms. A metabolite of thiamethoxam in soil is clothianidin.