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Pest Control L7

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Pest Control L7 English in Natural Science Definitions Pest: animal species that interferes with human activities Weed: a plant pest Pest ... – PowerPoint PPT presentation

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Title: Pest Control L7


1
Pest ControlL7
  • English in Natural Science
  • ???????

2
Definitions
  • Pest animal species that interferes with human
    activities
  • Weed a plant pest
  • Pest control reduction of pest/weed populations
    to not damaging levels
  • Damage is measured in economic terms
  • Eradication (pest extinction) is practically
    impossible

3
Control of pest/weeds more crop yield
4
Integrated Pest Management (IPM)
  • Use all methods of control in a scientific manner
    to reduce crop damage due to pests, weeds and
    diseases
  • Strategies
  • Natural control natural enemies
  • Biological control introduced predators,
    parasites or diseases reproductive control
  • Agronomic control crop rotation, strip cropping,
    burning, mulching,
  • Pesticides treatment with chemical poisons

5
Agronomic control
  • Crop rotation
  • Change conditions for pest development
  • Based on life cycles
  • Strip cropping
  • Protect and foster natural enemies
  • Lower pest densities
  • Burning of crop residues
  • Destroy pest larvae
  • Re-start from scratch - secondary succession
  • Mulching
  • Avoid weeds
  • Light competition
  • Chemical allelopathy

Sustainable solutions (1-3 years) Require
continuous use Alone or combined
6
Biological control
Long-term solutions Sustainable
  • Scientific basis
  • Each pest has natural predators, parasites and
    competitors
  • Bring equilibrium predator-prey below the
    economic threshold of pest

7
Efficacy of biological control
  • Cottony-cushion scale
  • (Icerya purchasi, Hemiptera)
  • Native country Australia
  • Pest problem in California
  • Discovered 1872
  • Pest in Citrus orchards (1887)
  • Control
  • Cyanide pesticide failure
  • parasite (Cryptochaetum iceryae, Diptera)
  • vedalia (Rodolia cardinalis, Coleoptera)
  • Achieved in 1 year
  • Total cost 1,500
  • Prickly pear (Opuntia stricta)
  • Native countries Mexico, South America
  • Weed problem in Australia
  • Ornamental (1839)
  • Weed invasion 1880-1925
  • 243,000 km2 prickly thickets
  • Control moth Cactoblastis cactorum from
    Argentina
  • Achieved in 10 years (1940)

8
Parasites and diseases
  • Rabbits (Oryctolagus cuniculus) introduced in
    Australia (1859)
  • 20 years later became a serious pest ate pasture
    ? desertification
  • Control mixoma virus (Leporipoxvirus) from S
    America (1950)
  • Problems
  • escape in Europe (non-target area)
  • resistance by natural selection (1965) BUT
    populations reduced lt threshold

9
Problems of biological control
  • Success rate 16 (Hall et al., 1980)
  • Reasons
  • One species controls better than several
  • Competition loss of efficacy
  • Introduced species may prey on non-target species
  • Reduce efficacy
  • Side-effects on ecosystems
  • To be effective
  • Only if economic injury exists
  • Specialist predators/parasites
  • Generalist snail (Euglandina rosea) eliminated
    60 of native snails in Hawaii
  • Indian mongoose (Herpestes auropunctatus) in
    Hawaii, Okinawa and Pacific Islands
  • After research on ecological effects demography

10
Sterilization
  • Irradiation of male insects (USDA, 1950s)
  • Background
  • X-rays caused sterility in male insects (1916)
  • Dr Edward Knipling (1954) in screw-worm fly
    (Cochliomyia hominivorax) - subtropical America
  • livestock in Florida
  • Forest insects in Canada
  • Melon fly (Bactrocera cucurbitae) in Okinawa
    (1972-1993) Koyama et al. 2004
  • Tse-tse fly in Rhodesia

11
Immunocontraception
  • Vaccine that reduces fertility
  • glycoproteins (ZPG) inhibit egg fertilization
  • Effective against wildlife populations
  • Deer in New York
  • Rabbits in Australia (invasive species)

12
Efficacy of immunocontraception
  • Sterilization produces fewer offspring
  • Surviving animals live longer - compensation
  • High level of sterility is required (gt80 females)

13
Pheromone traps
  • Pheromones chemical substances used by animals
    (mainly insects) to communicate
  • Moths and bark beetles
  • Kinds
  • aggregation
  • sexual - released by females to attract males
  • Advantages
  • Species specific
  • Sex specific pheromones most effective (99)
  • Tiny amounts used as baits
  • Work at long distance (30 kms)
  • No possible resistance
  • Shortcomings
  • Only adult insects
  • Not applicable to all insects pests
  • Seasonal efficacy (mating season)

14
Chemical control Pesticides
  • Pesticides are a short-term solution, the last
    tool to be used in IPM because
  • Contaminate the environment (water, soil, air)
    and agricultural products (residues in
    vegetables, meat)
  • Non selective affect also non-target species
  • Pest species eventually become resistant
  • In some cases have produced more pest problems
  • When can be used?
  • Whenever there is economic injury and other
    treatments are not effective

15
Kinds of pesticides
Insecticides Herbicides Fungicides
Insect pests Weeds Fungal diseases
Neurotoxic Photosynthesis Inhibitors
Organochlorines Triazines Respiration
Organophosphates Phenylureas Phthalates
Carbamates Benzo-nitroamines Protein synthesis
Pyrethroids Germination Other synthesis
Neonicotinoids Nitroanilines Triazoles
Natural compounds Chloroacetamides Cell division
Growth regulators Growth inhibitors
Stomach poisons Phenoxy-alkane
Repellents Defoliants
16
Pesticides efficacy
Economic benefit crop value - cost of control
  • Pesticides ? less economic benefit
  • Control cost
  • Chemicals
  • Spraying equipment
  • tractor booms
  • airplane or helicopter
  • Personnel (applicators)
  • Despite increasing use after 30 years
  • More pests
  • More crop losses

17
Insecticide problems for pest control
  • Kill natural enemies
  • Foster outbreaks of insects which become pests
  • California red scale (Aonidiella aurantii) on
    lemon trees after DDT
  • Cottony-cushion scale (Icerya purchasi) on Citrus
    after DDT
  • insects in rice crops (1965-1970)

18
Paddy fields in Japan
After Kiritanai (1992)
19
Pesticide effects on ecosystems
  • Direct effects due to toxicity
  • Mortality insecticides gtfungicidesgtherbicides
  • Sublethal (non-target organisms)
  • Stress parasites and diseases
  • Reproduction endocrine disruption (OC
    insecticides)
  • Abnormal growth (malformation)
  • Indirect effects - trophic web
  • Food depletion starvation death
  • migration
  • Herbicides phytoplankton consumers
    starvation
  • Insecticides zooplankton algal blooms

20
Decline of birds of prey
  • 1963 Ratcliffe survey of Peregrine falcon in UK
    1/5 birds bred successfully
  • 1964 Hickey et al. surveys in US confirmed
    trend and raised alarm - raptors were
    disappearing due to continuous reproductive
    failures

Why?
21
  • 1966 Ames reproductive failure of birds of prey
    correlated to shell-thinning
  • 1967 Ratcliffe eggshell thinning in certain
    raptors since 1947 (Nature 215208)
  • Hickey Anderson eggshell thinning in
    predators / fishing-eating birds
  • pesticides blamed

DDT in agriculture (England)
22
  • 1969 Laboratories confirmed the cause of
    eggshell thinning organochlorines
  • Until 1974 debate on how DDT and organochlorines
    affected eggshell thinning
  • DDE caused shell thinning in birds of prey, but
    not in gallinaceous species (Cooke, 1975)
  • PCBs did not cause eggshell thinning (Peakall,
    1993)

23
Partridge (Perdix perdix) in many countries
  • Causes of decline
  • Nest loss (26)
  • chick mortality (29 ? 44)
  • hunting (7)
  • winter loss (38)

Potts (1986)
24
Decline of birds due to pesticides
  • Herbicides eliminate weeds ? reduce insects and
    seeds
  • Food shortage (insects, seeds) increase chick
    mortality

Species Year decline started Farmland () Countrywide ()
Tree sparrow (Passer montanus) 1978 -87 -76
Turtle dove (Streptopelia turtur) 1979 -85 -62
Grey partridge (Perdix perdix) 1978 -82 -78
Spotted flycatcher (Muscicapa striata) Before 1969 -78 -78
Skylark (Alauda arvensis) 1981 -75 -60
Song thrush (Turdus philomelos) 1975 -66 -52
Lapwing (Vanellus vanellus) 1985 -46 -42
25
Transport routes
26
Pesticide losses
Transport route Category applied rate
Spray drift Aerial application Ground-rig Manual (backspray) 5 - 10 0.1 3 ?
Volatilization Very volatile Less volatile 50 - 90 1 - 10
Leaching Water soluble Moderately soluble 40 - 90 10 - 25
Runoff Water soluble Insoluble 3 - 6 1 - 2
Difficult to estimate due to sorption and slow
movement
99 Pesticide losses ? environmental
contamination
(Pimentel et al., 1992)
27
Dissipation of pesticides
Half-life the time required to reduce to half
the amount of a substance
28
Residues in crop plants and products
29
Ensuring food safety
  • Cost of the Green Revolution
  • Check residue levels in food
  • National produce (market)
  • Imports from other countries (31 Quarantine
    Stations Japan)
  • Analytical laboratories
  • Huge cost for governments
  • Reject food with residues gtMRL
  • (Maximum Residue Limit)

Imported (2001) Tested Residues found
Fresh vegetables 997,000 67,796 (6.8) 729 (1.06)
Frozen vegetables 717,000 21,501 (3) 93 (0.43)
Total food items 32.5 million 2.4 million (7.4)
Figures indicate tons
30
References
  • Charles J. Krebs, 2001. Ecology 5th ed. /
    ??????? room B-226
  • David Pimentel, 1991. Handbook of Pest Management
    in Agriculture. CRC Press, Florida, USA
  • F. Moriarty, 1983. Ecotoxicology. Academic Press
    / ??????? room B-207
  • Rachel Carson, 1962. Silent Spring. Houghton
    Mifflin / ??????? room B-207
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