The honeybee is nature's"workhorse — and we took it for granted... We've hung our own future on a thread”Prof. E.O. WilsonHarvard UniversityInsect + Biodiversity Expert + Pulitzer Prize-winning Author of many books including “ The Insect Societies” + "The Creation: An Appeal to Save Life on Earth"
Multi-routes of pesticide exposure for honey bees…Received/ accepted/ published… Jan 2012(How is this paper organized?) • Abstract – Bees colonies decline + pesticide results • Introduction – Background on Colony collapse disorder • Results – Short but + 6 Tables of data ! • Discussion – Data compared to literature • Materials + Methods: prep + analysis field and lab methods • Acknowledgements – thanks anonymous reviewers ! • References – 36 listed.
Abstract: summary of problem + research • Neonicotinoid insecticides “blamed” • known to be highly toxic to bees • 2 types are researched in this paper: • Clothianidin (CL)+ • Thiamethoxam(TH) • How can bees be exposed? • Foraging flowers • seed planter exhaust • soil
Introduction: Background Info • Bees are important crop pollinators • Bee populations are declining worldwide What are potential causes? • Parasitic mites: hard to kill = spread easy • Viruses: also spread easily • Pesticides: insecticides, miticides, fungicides, herbicides are found in pollen + bee wax • high fructose corn syrup: may contain toxins
Deadly parasitic Varroa mite on the back of a honey bee. (Credit: Scott Bauer)
Intro. – Neonicotinoid Pesticides • Low vertebrate toxicity: thought “safe” • Highly toxic to bees: LD50 = 22-44 ng/bee (contact) or 3 ng/bee (oral) • LD50 = lethal dose to kill 50% of tested critters • 1,000,000,000 ng = 1 gm • Persistant: half-life = 148-1155 days for CL • ½ life = time for half of substance to disappear • Effect: insect neural nicotinic acetycholine receptors to “fire” continuously leading to death
Intro: Corn • Largest “single use” of land in N. America • 35.7 million hectares (2010) • Neonicotinoid Pesticidesare applied to the seed coats before planting on 99.8 % of corn (except for the 0.2% organically grown). • Applied at 0.25-1.25 mg/kernal • x 12,500 kernals/hectare • x 35.7 million hectares = • Dead bees tested had Clothianidin or Thiamethoxam • Healthy bees + healthy hives had no CL or TH
Results: Table 1 – Soil Samples Soy and Corn soils show levels of pesticides.
Table 1 - Soils • Soil residues even after 2 years • easily spreads off-site
Table 2 = Talc Talc residues are very high in pesticides Levels are toxic and very mobile
Mite chemical “baits” • Scientists have developed a new bait that may help control varroa mites, the top pest of honey bees. • the mites encounter a more heady bouquet of honey bee odors that lure the parasites away from their intended hosts and onto the sticky boards, where they starve. • In preliminary tests, 35 to 50 percent of mites dropped off the bees when exposed to the attractants. Free-roving mites found the semiochemicals even more attractive, according to Teal. http://www.sciencedaily.com/releases/2009/07/090705145109.htm
High Fructose Corn Syrup • Although small backyard beekeepers traditionally feed bees a mixture of sugar and water when colonies need extra food, commercial beekeepers largely use high fructose corn syrup. • HF corn syrup is cheap and easy to get in the U.S... but some scientists think feeding bees corn syrup could be one cause of colony collapse disorder.
Hydroxymethylfurfural (HMF) • Research in the Journal of Agricultural and Food Chemistry reports conditions, including heat, where potentially dangerous levels of hydroxymethylfurfural (HMF), a toxic substance, form in high-fructose corn syrup. • This may suggest soft drinks + other human foods with high-fructose corn syrup have HMF. http://www.sciencedaily.com/releases/2009/08/090826110118.htm
Discussion • Bees exposed to pesticides at fields – • A single seed with 0.5 mg/kernal Neonicotinoid has enough toxin to kill 80,000 bees. • Talc residues are extremely high in Neonicotinoid pesticides • Neonicotinoid pesticides are found in pollen + plant fluids • Soil have residues even after 2 years • Bees forage 50% of their pollen from corn • Pollen in healthy hives have <1/3 pesticide levels
The Literature on Neonicotinoids: • Neonicotinoid Pesticides in leafdroplets at 10-199 mg/l results in paralysis + death • Delays in worker bee development • High humidity may be required to kill bees (even at 100 ng CL / bee) • Corn pollen 10x more toxic than Canola • Nurse bees eat 65 mg pollen in 10 days which might result in 50% of the LD50 dose • Fungicide Propicozole – synergistic toxicity
Translocation of Neonicotinoid Insecticides From Coated Seeds to Seedling Guttation Drops: A Novel Way of Intoxication for Bees • Guttation is when xylem fluids are released at leaf margins to attract ants. Leaf guttation drops from corn plants germinated from neonicotinoid-coated seeds contained amounts of insecticide constantly higher than 10 mg/l, with maxima up to 100 mg/l for thiamethoxam and clothianidin, and up to 200 mg/l for imidacloprid. • http://esa.publisher.ingentaconnect.com/content/esa/jee/2009/00000102/00000005/art00011
The Obsession With Lawns, a magazine article argues lawn care is harming is the bee population – which begs the question, where have all the bees gone? http://www.lowdensitylifestyle.com/FREE,%20flexibility,%20fluidity/colony-collapse-disorder/