The bee pollinates the Varroa mite preys on adult bees and their larvae
Only 100 plants, animals, fungi and microbes cause 90% of the problems ¾ of all species on earth are insects
Human disrupted ecosystems have increased the growth rate of insects Human disrupted ecosystems have decrease growth rate of beneficial insects
Pests annoy, distract and disrupt Pesticides kill pests and can be general or specific Biocide is broad-spectrum Herbicides kill plants Insecticides kill insects Fungicides kill fungi
Early Methods of Pest Control Smoke – Salt – Insect-Repelling Plants 5000 ya Sumarians used sulfur 2500 ya Chinese describe mercury and arsenic compounds for body lice Greeks and Romans used oil sprays, sulfur, lime, Burned fields and rotated crops Acids, Alcohol, spices
1939 Swiss Chemist Paul Muller discovered DDT Dichloro-diphenyl-trichloroethan Inexpensive, stable, effective Lethal to numerous insects nontoxic to mammals Stability leads to biomagnification, Harmful to other non-target species (eggshells were thinning in birds)
Use in US amounts to 5.3 bill lbs or 2.4 metric tons annually 1½ of this is for chlorinating water (purifying) 2Convention Use includes insecticide, fungicides and herbicides 80% is for agriculture 3Wood preservative
globally Convention use in the world is 5.7 bill lb annually of which 1.24 bill lb in US annually or 20%
Types of Pesticides PESTICIDEEXAMPLESSTABILITY/ PERSISTENCE TYPETOXICITY S, Ar, Cu, Hg, leadSeed storage, kill rodents stableinorganicHigh, neurotoxins Botanicals; nicotine, rotenone, pyrethrum, turpentine, phenols, Rotenone kills fish Natural hydrocarbons herbicides general biocide Relatively non- persistent and variable Organic “natural” variable Small molecules that gas easily and penetrate rapidly Carbon tetrachloride, carbondisulfide, methyl bromide used to sterilize soil BannedFumigantsExtremely dangerous for workers Herbicide insecticide 2,4,5T DDT Stable and persistent Many banned Chlorinated hydrocarbons toxic MALATHIONOutgrowth of nerve gas, inhibit cholinesterase unstableOrgano- phosphates toxic SevinLow persistence and low bioaccumulation CarbamatesVery toxic to bees Living organismBacillus thuringiensis Parasitic wasps Biocontrola
Pesticide Benefits Controls disease malaria deaths are thought to have decreased by 50mill in 50yrs (other diseases carried by mosquito, yellow fever, west nile, encephalitis or fly trypanosomiasis or sleeping sickness or by worms) Crop yields possibly 1/3 Farmers save $3-$5 /$1 spent pesticide
Pesticide Problems Poison nontarget species: Pollinating bees have been killed due to nondiscriminatate use of pesticide Sevin Insecticide Axodrin (target potato aphids ) killed 10,000 robin in 3 days Accidental spillage can wipe out ecosystem Increase pest resistance: The Varroa mite that parasitizes bees has developed resistance to two different pesticides since 1987. The cotton boil weeval was controlled with DDT but the weevil quickly developed resistance. 50-60 of the resurgence is when pop rebuilds quickly and with resistance rebound pesticide treadmill the demand for greater and greater amounts of pesticide due to resurgence
We are losing the battle to control pest using synthetic pesticides Evidence… Larger percentages of crops are lost now to insects, disease and weeds than in 1944 *gene transfer is thought to confer resistance in species that have never seen the pesticide.
GMO Crops having increased resistance Theoretically should decrease usage of pesticides Likely to cause even more resistance
Pesticide misuse includes “broadcast spraying” and broad spectrum pesticides Under natural conditions many agr pest are kept under control with natural enemies i.e. Wasp predators
i.e. In Peru, both boll weevils and Heliothis worms began increasing rapidly following DDT use because it killed the predatory wasp Yield changes 500kg/hec before DDT 750 kg/hec after DDT and Toxaphene 330kg/hec after death of the wasp
In California Cotton yield down by 20% Even with doubling of insecticide
Another part of the problem with the use of pesticides Farmers abandon –using mixed crops –Crop rotation –Traditional methods of management
Persistent pesticides can move long distances in the environment Chlorinated hydrocarbons (DDT) are stable, soluble and toxic High solubility in fat bioaccumulation and magnification
POP Accumulate in polar regions due to the “grasshopper effect” evaporate from warm regions and condense and precipitate in colder regions. 31 million kg (70 mil tons) of Atrazine annually makes it the biggest commercial pesticide. Shown to cause abnormal gender changes in frogs at low but not high levels due to the estrogen
Inuit people have the highest levels of POP in any human population Picture of inuit people
POP’S They are so long lasting and dangerous 127 countries agreed in 2001 to a global ban on the dirty dozen (DDT, PCB’s, dioxins)
Two varieties of Jimsom weed (Datura wrighti) 1. with glandular trichomes full of sticky sweet substance More resistant to herbivory Trait is dominant 2. without glandular trichomes Both produce toxic alkaloid call atropine that protects plants from insects
Human Health Problems are either Acute or Chronic Acute –Poisoning and illnesses caused by high doses and accidental exposure Two thirds of 9000 latin american flower worker experienced blurred vision, nausea, headaches, conjunctivitis, rashes and asthma.
Chronic include cancer, parkinson’s disease, birth defects, immune problems, degenerative diseases. Many flower and farm workers reported stillbirths and miscarriages and neurological problems. Farmers who use pesticides have elevated levels of prostate cancer, non-Hodgkins lymphoma, Parkinson’s disease.
Children from homes fumigated by professional bug exterminators are 3X more likely to have acute lymphocytic leukemia
ALTERNATIVES Crop ROTATION Burn Crop Residues, Use cover crops Switch from monoculture to polyculture Adjust planting time
Biological Controls Pest predators (wasps, ladybugs, praying mantises) Pest pathogens (viruses, bacteria, fungi) –Bt naturally occurring bacterium that kills larvae of butterfly and moth –Use 2o consumers (ducks, geese, chickens) –Herbivorous insects have been used to control weeds.
Integrated Pest Management Mechanical techniques like vacuuming bugs off crops Use minimum amount of pesticide necessary. Avoid broad spectrum products **Risk is that it introduces new organisms into an environment**