Conferences in Insect Pest Management Chile, 410 November, 2005 7 November, University of Talca

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Conferences in Insect Pest Management Chile,
4-10 November, 20057 November, University of
Talca
Ecological engineering as a valuable technique
for managing resistance
Steve Wratten National Centre for Advanced
Bio-Protection Technologies, Lincoln
University, New Zealand
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Ecological engineering to manage resistance
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• But first detect resistance bioassays/DNA

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Utility of DNA markers in biocontrol

• Provide genetic information useful in absence
  of morphological or behavioural information
• Descriptive - strains/biotypes/cryptic species
• - immature life stages
• - host parasitoid/pathogen mixtures
• Analytical - genetic diversity
• - spatial/temporal distribution -
  geographic origins
• - risk assessment

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To design of DNA markers, need to know

• which part of the genome will be informative
• how it is best analysed
• access to specimens of known species identity

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Insect mitochondrial DNA Map
Control region (3)
Cytochrome oxidase (2)
Ribosomal RNA (1)
Cytochrome B (2)
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Analytical process

• STEP PROCEDURE
• 1. Extract DNA salt, organic, magnetic
• 2. Isolate gene region PCR amplification
• 3. Detect gene fragments electrophoresis or
• chromatography
• (fluorescence)

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Analytical process

• STEP PROCEDURE
• 1. Extract DNA salt, organic, magnetic
• 2. Isolate gene region PCR amplification
• 3. Detect gene fragments electrophoresis or
• chromatography
• (fluorescence)

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PCR preparation in sterile environment
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PCR requires

• Genomic DNA template
• Primers (synthetic, single strand)
• dATP, dGTP, dCTP dTTP building blocks
• Polymerase enzyme
• Magnesium cofactor
• Buffer

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Western agriculture Biodiversity, including
biodiversity which can complement insecticide use.
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Classical biocontrol 10 success
The biocontrol agent may need pollen, nectar,
shelter, alternative hosts.
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• Biological control of pest animals, weeds and
  diseases can be elegant, self-sustaining,
  non-polluting and cheap when it works!

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• And native, background biocontrol has been
  reduced to low levels by conventional
  agriculture. How do we know?
• Prey facsimiles

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Fig. 3.3 Mean rate of predation (per cent
removal/24h) of aphids and fly eggs in selected
fields.
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Chocolate-box ecology?
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Shelterpollennectaralternative prey
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• Very visual marketing advantages too

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Hierarchy of effects when flowers are added to
agro-ecosystems

• Parasitoids aggregate on flowers
• Parasitoid fitness improved
• Higher parasitism rate
• Host population reduced
• Host population reduced to below economic
  threshold

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1. Natural enemies aggregate

• e.g., yellow traps in buckwheat in New Zealand
  vineyards

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1. Natural enemies aggregate

• e.g., sweep netting in buckwheat in New Zealand
  vineyards

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2. Fitness improved Longevity

• e.g., Trichogramma /- honey

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2. Fitness improved Longevity

• e.g., Dolichogenidea tasmanica (Braconidae)

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A phacelia flower
Upward projecting hairs on the style
Stamen appendages partly protecting nectaries
Nectaries
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Longevity of D. tasmanica with and without
alyssum flowers
P lt 0.01 P lt 0.001
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Lifetime fecundity with and without alyssum
flowers
P lt 0.001
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Mean offspring sex ratio with and without alyssum
flowers
P lt 0.01
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3. Parasitism rate increased

• e.g., potato tuber moth in Australian potatoes

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PEST Potato moth, Phthorimaea operculella Zell.
(Lep Gelechiidae).
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Tuber damage
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Borage, Borago officinalis
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Buckwheat, Fagopyron esculentum
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Nasturtium, Tropaeoleum majus.
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Faba bean, Vicia faba (extrafloral nectaries)
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Phacelia, Phacelia tanacetifolia.
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Benefit to wasps
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Benefit to moths
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Rate of potato moth parasitism within
borage-bordered crop (P 0.001)
Unsown
Unsown
14.2 a
15.2 a
21.8 a
63.0 b
Unsown
Borage
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Hoverflies higher field fecundity near yellow
plastic!
Day, Hickman and Allen (Southampton University,
UK) unpublished
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3. Parasitism rate increased

• BUT flower species important

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Damaged leaflets per 15 m row within
buckwheat-bordered crop (P 0.002)
Unsown
Unsown
13.7 a
19.3 a
15.7 a
34.3 b
Unsown
Buckwheat
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Damaged leaflets per 15 m row within
borage-bordered crop (P 0.896)
Unsown
Unsown
24.7 a
22.7 a
22.1 a
25.3 a
Unsown
Borage
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Leafroller damage
Direct damage
Indirect damage
Larvae feed on berries, stalks, leaves
Larval feeding provides entry sites for Botrytis
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Parasitism rates
Average (se) number of leafroller larvae that
were parasitised by D. tasmanica in areas of
vineyard planted with and without buckwheat
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Leafroller abundance
Average (se) number of leafroller larvae per
bunch
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Host population reduced

• e.g., hoverflies reduce aphid population when
  Phacelia planted next to wheat

Hickman Wratten 1996
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• Key research questions for the future
• Nectar sugar signatures to identify best
  flowers?
• How far do natural enemies travel after using
  floral nectar?
• anti-oxidants in buckwheat (Fagopyrum) nectar
• as markers?
• native plants as nectar sources
• modelling
• selective biodiversity, including 4o trophic
  level
• attract and reward herbivore-induced plant
  
• volatiles (HIPVs)

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Modelling effects of enhanced fitness
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Selective biodiversity
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Pest/beneficials dilemma in CBC
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Pest/beneficials dilemma in CBC
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Pest/beneficials dilemma in CBC
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Pest/beneficials dilemma in CBC
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Pest/beneficials dilemma in CBC
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Pest/beneficials dilemma in CBC
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Pest/beneficials dilemma in CBC
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Pest/beneficials dilemma in CBC
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Pest/beneficials dilemma in CBC
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Pest/beneficials dilemma in CBC
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Pest/beneficials dilemma in CBC
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How do we achieve selective resource subsidies?

• At least 11 selectivity levels
• Resources available only to natural enemy
• Relative advantage to natural enemy
• Additional selective effects

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A medium sized parasitic wasp in the family
Ichneumonidae
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A small parasitic wasp in the family Braconidae
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Hierarchy of SelectivitySelective availability
to natural enemy
(Lavandero et al., in prep.)
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Hierarchy of SelectivitySelective availability
to natural enemy
(Lavandero et al., in prep.)
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Hierarchy of SelectivityNatural Enemy gt Pest
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Practise

• Ecosystem engineering

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Conferences in Insect Pest Management Chile,
4-10 November, 20057 November, University of
Talca
Ecological engineering as a valuable technique
for managing resistance
Steve Wratten National Centre for Advanced
Bio-Protection Technologies, Lincoln
University, New Zealand