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bboeken@bgu.ac.il
http://www.bgu.ac.il/desert_agriculture/Agroecology/
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© BBoeken 2005-15

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–   Vertebrates
–   Insects
–   Mites
–   Nematodes
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–   Competitors for resources
–   Co-dispersers
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–   Fungi
–   Bacteria
–   Viruses
Red Sunflower Weevil ipmworld.umn.edu
Rose Mosaic Virus www.huntingtonbotanical.org
Soybean Cyst Nematode nematode.unl.edu
Black Bean Aphid www.inra.fr
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Reduction of net yield
–   NPP-consumption
–   Damage to roots, foliage, flowers, fruits
–   Disproportional reduction of market value
Species specificity
–   Generalists
–   Specialists
Net Assimilation Rate
Relative Growth Rate
Aspergillus and insect damage www.apsnet.org
Crop infestation
–   Plant density and apparency
–   Accessibility
Secondary metabolism
Stamp, N. 2003. The
Quarterly Review of
Biology 78,23-55
Plant defense
–   Bottom-up control
–   Structural protection
–   Secondary compounds (quantitative/qualitative)
–   Costs and benefits (defense-growth trade-off)
–   Defence and tolerance
–   Genotypic or phenotypic expression
–   Constitutive or inducible defense
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(Top-down control)
•   Predators
–   Vertebrate insectivores
Birds, lizards, shrews
Generalists
–   Predatory insects (ladybugs, lacewings, beetles, mantises)
Specialists on common pests, incl sessile pests
(Aphids, scale insects, etc.)
–   Spiders
Generalists of moving prey, not sessile insects
Also of predators and
parasitoids
Araneus diadematus
André Karwath en.wikipedia.org
Blackbird
Sannse en.wikipedia.org
•   Parasitoids
–   Syrphid flies, ichneumonid wasps
Specialists on larvae and sessile insects
Parasitized by hyperparasites
Aleiodes indiscretus wasp parasitizing a gypsy moth caterpillar. Scott Bauer en.wikipedia.org
•   Pathogens
–   Fungi, bacteria, viruses
Host-specific
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Graham Burnett, en.wikipedia.org
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•   Insecticides
–   Heavy metals
•   Lead, mercury, arsenic
–   Plant toxins
•   Nicotine, pyrethrum
–   Organochlorines
•   DDT, Dieldrin, Lindane
–   Organophosphates
•   Parathion, Malathion
•   Advantages
–   No more insect damage
–   Quick and easy application
•   Disadvantages
–   Selection of resistance
–   Increasing use
–   Kills all insects
–   Accumulates in food chain
•   Causes thin egg shells in birds
–   Spreads in the environment
–   Dangerous to handle
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•   Consumption rate
•   Population response to prey density
•   Giving-up density
•   “Ideal Free Distribution”
A. Functional response B. Numerical response
Consumer aggregation
Food density
Food depletion
Food density
C. Ideal Free Distribution
Consumer density www.agedstore.com
•   Life-cycle synchrony
•   Availability, colonization
•   Prey-switching
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Use of plant defenses
–   Repellants
–   Decoys
–   Low crop density
–   High genetic crop diversity
Pyrethrum field www.dpiwe.tas.gov.au
•   Landscape diversity (habitats)
•   Nesting sites, refugia
•   Alternative prey
Colorado potato beetle en.wikipedia.org http://www.simplynaturalorganic.com
Physical means
–   Hand picking (large insects)
–   Solarization
•   against weeds and soil nematodes
•   instead of herbicides and Methylbromide 8

Augmentation of natural enemies and introduction of exotics
(Risk of invasiveness!)
•   Weed herbivores
–   Aphthona lacertosa (feeds on leafy spurge roots)
•   Predators
–   Rodolia cardinalis on cottony cushion scale
•   Parasitoids
–   Ichneumonoid wasps (oviposit in aphids)
•   Parasites
–   Nematodes ( Phasmarhabditis hermaphrodita on slugs)
•   Pathogens
–   Fungus ( Trichoderma viride)
•   Bacteria ( Bacillus thuringiensis )
–   Toxic if ingested
Icerya purchasi - Infestation of citrus plantations in California, 1888
(http://www.bugwood.org)
Aphthona lacertosa, an introduced root-feeding flea beetle.
The predator, Vestalia ladybird -
Rodolia cardinalis , from Australia
(http://www.ento.csiro.au/)
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•   Bt plants
–   Insertion of Bt plasmid into crop plant genome
–   Specific Bt plasmid for particular pest
–   Insect herbivores die upon ingestion
–   Low chance of resistance
•   Advantages
–   Yield increase due to absence of herbivory
–   No use of chemical pesticides
–   Presumably no effect on non-pest insects
and higher trophic levels (?)
Bacillus thuringiensis
JDeacon helios.bto.ed.ac.uk
•   Other applications in plants
–   Vitamin A production
–   Roundup–ready crops
•   Broad toxicity and bio-accumulation
•   Resistance leading to superweeds
–   ‘Terminator’ genes
•   Sterile second generation http://cls.casa.colostate.edu/TransgenicCrops/index.html
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•   Ineffective on sucking insects
–   Mirid leaf bugs on Bt-cotton
•   Possible adverse effects on insect diversity
–   Pollen-eating non-target insects
on Bt-corn ( Zangerl et al. 2001 )
–   Pollinators
•   Low crop diversity
–   Few cultivars used for technique
–   Regional crop diversity threatened
•   Societal issues
–   Dependence on few large companies
–   Legal aspects (patents on GMOs!)
–   Package deals with other products
–   Corporate business monopoly
–   Human health concerns
Potato diversity, Peru
(http://nissa.ger-nis.com)
See also the Convention on Biological Diversity,
Rio de Janeiro 1992 (http://www.cbd.int/) 11