Some Crops pollinated by Bees
The honeybee is nature's
"workhorse — and we took it
for granted... We've hung
our own future on a thread”
Prof. E.O. Wilson Harvard University
Insect + Biodiversity Expert + Pulitzer Prizewinning Author of many books including
“ The Insect Societies” + "The Creation: An
Appeal to Save Life on Earth"
What do we mean by Ecosystem Services?
The Problem:
Dead Bees outside a hive
US honey colonies (Millions) 1945-2007
Colony Collapse Disorder 2007
Educational Cartoon
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 Pesticides are 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 samples
Table 2 = Talc
Talc residues are very high in pesticides
Levels are toxic and very mobile
Table 3 - Corn Pollen samples
Table 3 - corn pollen
Table 4 - Bee pollen samples
Table 4
Table 5- Bee and hive samples
Table 5
Table 6 – Soil + Dandelion samples
Table 6
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. Freeroving mites found the semiochemicals even more
attractive, according to Teal.
http://www.sciencedaily.com/releases/2009/07/090705145109.htm
Survivorship of bees being fed
HFCS feed vs Sucrose
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 leaf droplets 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 neonicotinoidcoated 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/