Citrus Gall Wasp

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Citrus Gall Wasp
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Life Cycle

• One generation per year
• Adults emerge October- late November (Sunraysia)
• Mate and immediately lay eggs into surrounding
  spring flush twigs
• Adults die within a week to ten days
• Eggs hatch in 2-4 weeks and larvae burrow into
  the twig

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Adult

• Shiny, black, 3mm (native to Australia)

Laying eggs into twig
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Larvae

• Larvae white 2mm

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Varieties Attacked

• Native host is the Finger Lime
• Grapefruit and lemons most susceptible, then
  oranges.
• Mandarins least susceptible
• Rough lemon and Troyer citrange rootstock trees
  are most susceptible, but have noted on Sweet
  Orange and Trifoliata
• CGW incursion in Monash, SA and Griffith, NSW

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Management Options

• Best control strategy will be a combination of
  all strategies
• Prune out / hedge heavily infested trees
• Introduce parasites (do not spray blocks that
  have had a parasite release).
• Spray supracide on heavily infested blocks to
  kill newly hatch larvae

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Pruning/Hedging

• Pruning in winter is an excellent way to remove
  galls
• Galls dry out and larvae are killed
• Do not allow rootstocks of susceptible varieties
  to develop shoots,
• can become heavily infested sites

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Natural Enemies

• Parasitic Wasp
• Megastigmus spp

M. trisulcus
M. brevivalvus
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Natural Enemies

• Begin to emerge about 2 weeks after first gall
  wasps emerge
• Find gall wasp eggs and lay their eggs within the
  gall wasp egg
• Parasite grows within the larvae of the CGW and
  eventually destroys the CGW
• In some areas up to 90 of CGW eggs can be
  parasitised, can take 4 5 years to establish.
• Parasite release was funded by MVCB in 2007 and
  combination of HAL and MVCB funding for 2008 to
  2010 (look at an extension if needed)
• Timing problem as parasites are only available in
  early November

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Pesticide Spray

• Targeting emerging adults are difficult as they
  are short lived emerge over a protracted period
• Pesticide must have systemic properties
• Contact insecticides will not penetrate bark and
  kill larvae
• QLD research suggest Supracide ( oil) can kill
  most newly hatch larvae if timed correctly
• Action level for spraying, 33 or more branches
  infested with galls exceeding 50mm in length and
  low in parasites

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Spray Timing is Critical

• Single Spray (least disruption)
• Two Sprays
• Three Sprays

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Spray Options

• Oscillating boom spray (125mL/100L) 45L per tree
• Supracide very harmful against beneficial
  insects and repeated use may cause other pest
  problems
• With-holding Period 21 Days
• Reintroduction of natural enemies