What is a pest?

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What is a pest?

• Biological Pests are organisms that reduce
  availability, quality, or value of resources to
  humans. Whether something is a pest, depends on
  ones perspective.

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• Large swarms of mosquitoes can be very annoying
  to us, and also pose a risk for disease, but they
  are an important food source for many organisms.

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• Large animals can become pests also, I took a
  class in college called vertebrate pests.
• Examples snakes, sharks, horses, elk, and
  bears.
• We realize now that these are important animals
  in ecosystems, but problems sometimes occur when
  humans and these animals interact.

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Pesticide chemical that kills a pest

• Biocide kills all living organisms, dont like
  these!!!
• Narrow agents that focus on killing a specific
  organism
• Fungicide
• Herbicide
• Insecticide

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• Humans have been controlling pests for thousand
  of years, but the modern era really got underway
  in 1934 with the discovery of the insecticidal
  properties of DDT.
• DDT is one heck of a pesticide cheap, stable,
  and easily spread, is highly toxic to insects but
  relatively non-toxic to mammals.

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• Facts 90 of all pesticides are used in
  agriculture and food storage and shipping.
  Developed nations use 80 In developing
  countries the rate of increase is 7 to8 and in
  more developed 2-4

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Pesticide Types

• Inorganic broad spectrum, highly toxic,
  persistent, usually compounds of arsenic, copper,
  and mercury.
• Natural Organic Also refer to as botanicals
  usually derived from natural plant compounds

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• Chlorinated hydrocarbons DDT PDB are synthetic
  organic insecticides.
• Organophosphates parathion malathion an
  outgrowth of nerve gas research from WWII

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• Microbial agents and biological controls living
  organisms which help kill pests. These are used
  often in integrated pest management plans
• Lady Bugs!!!

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Benefits

• Disease Control About 500 million people suffer
  from malaria at any given time. 2 million die
  each year. It is estimated spraying for
  mosquitoes has prevented 50 million deaths over
  the last 50 years from malaria.

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• Diseases such as encephalitis, bubonic
  plague, sleeping sickness, and river blindness
  can all be reduced by use of pesticides.

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• Crop Protection Reliable data is hard to
  obtain, but some believe plant diseases, insect,
  bird, and weed competition can reduce yields by
  1/3.

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• Post Harvest can be as great as 20-30 from
  rodents, fungi etc. Some cases the damage caused
  by insects or fungal disease is mainly cosmetic,
  and this reduces the economic value of the crop.

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Problems

• Effect on non-target species estimates reach as
  high as 90 of pesticides never reach their
  target, and many beneficial organisms can be
  harmed.

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• Pesticide Resistance evolution in action.
  Those organisms most resistant and able to
  survive the chemical treatment survive and pass
  their traits onto the next generation.
• Thus, the next generation is harder to kill with
  the same pesticide.

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• In addition most pests reproduced rapidly and
  produce many offspring, thus a pesticide
  resistant population can be quickly established.
  This phenomenon is called pest resurgence.
• Thus it may take more pesticides (increasing the
  dose) or more toxic pesticides to control the
  pest.

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• Creation of New Pests By killing many organisms
  that are not pests, sometimes beneficial
  predators are also killed.
• New pests emerge, because their natural predator
  that kept their numbers in check, has been killed
  letting their population explode.

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Canete Valley in Peru

• DDT used on Boll Weevils, DDT resistant Boll
  Weevils appeared. Toxaphene replaced DDT, but
  eventually became ineffective. Heliothis worms
  began replicating rapidly and became a problem.
  The wasps which had helped keep both organisms in
  check had been decimated by the use of the
  pesticides.

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• Persitance and Mobility in the Environment DDT
  and other pesticides are often quite stable and
  do not break down easily in the environment.
• The build up in the food chain and can be
  transferred far from areas where they were
  initially used.

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• Examples Minnesota and Iowa 20 to 30 community
  and 30-60 private wells had detectable pesticide
  residues. Long range transport can occur as
  pesticides can move by rain and snow. Example
  Isle Royale in Lake Superior.

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• Human Health Problems Short term effects
  include acute poisoning and illness caused by
  relatively high doses and accidental exposures.

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• Long term effects suspected to include cancer
  birth defects immunological problems.
• Long term effects may be caused by very low doses
  of a variety of different chemicals, and are very
  difficult to tie to a specific source.

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Who?

• Farm workers who handpick fruit and vegetables
  (often migrant workers) are most effected both
  short and long term by pesticide exposure.
  Improper storage at home leads to 20,000
  Americans getting sick each year.

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Alternatives to Current Pesticide Uses

• Behavorial crop rotation, mechanical
  cultivation, habitat diversification (windbreaks
  ground cover, hedgerows) which provide habitat
  for natural predators, reduction of herbicide use
  etc.

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• Biological Controls Predators (wasps and
  ladybugs) pathogens (bacteria Bt and viruses)
  Certain birds
• Herbivorous Insects Australia, prickly pear
  cactus introduced, escaped gardens became
  prevalent in the wild, a natural predator from
  South America the cactoblastis moth helped combat
  the problem and has ate much of the cactus.

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• Genetics and Bioengineering release of sterile
  males into population interferes with
  reproduction. Production of crop varieties that
  produce natural insecticides, so that chemical
  spraying is not necessary.

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IPM Integrated Pest Management

• Combines many techniques to control pests.
  Pesticides still may be used as part of the
  overall plan, it is only one tool used to control
  them.

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• Vacuming bugs
• Mechanical cultivation
• Biological controls,

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• Timing pesticide application so one dose with a
  non-persistent chemical is used.
• Use of trap crops (planted earlier than main
  crop, pests are attracted to this crop, then it
  is destroyed with pests, leaving the main crop
  much less exposed to pesticides).

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Successful IPMs

• MA A group of apple growers have reduced
  pesticide use by 43 while maintaining crop
  yields equal to those using normal practices.
• Indonesia In 1986 banned 56 of 57 pesticides in
  current use. Crash course of IPM to train
  farmers. Reduced pesticide costs by 75 and had
  higher yields than their neighbors using normal
  practices.

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Regulating Pesticides

• 3 agencies EPA, FDA, and Dept. of Agriculture
• EPA regulates use and sale of pesticides under
  the Federal Insecticide, Fungicide, and
  Rodenticide Act.
• The FDA and Dept.Ag. Enforce pesticide use and
  tolerance levels set by the EPA.

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Delaney Clause

• In 1958 this clause was added to the FFDCA
  prohibiting the addition of any known cancer
  causing agent to processed foods, drugs, or
  cosmetics. This is a zero risk policy, and
  additives in use before 1954 were considered
  safe. Also pesticides registered after 1978 were
  subject to Delaney while those before had less
  stringent standards.
• Thus you could drink all the coffee you wanted,
  but food processors could not add a drop of
  coffee to their product.

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This is Insanity! So in

• 1996 it was amended with the standard of
  reasonable certainty of no harm, defined as no
  more than one case of cancer for every million
  people over a lifetime. Even this can be
  exceeded if a particular chemical would adversely
  affect consumers or disrupt the food supply.

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Complete Review Questions 1-5 for homework!

• Quiz over lecture and homework material. 10-15
  questions.

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• Thus, the next generation is harder to kill with
  the same pesticide.