MATERIALS
- Large plastic bins
- Paper towels
- Curtain mesh
- Elastic
- Small artist's paintbrush
- Regular supply of unsprayed green/yellow citrus fruit (lemons or grapefruit are best)
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From the start of your Greenhouse thrips colony to the release of your first Thripobius should take 20-50 days
STEP 1 - STARTING UP
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- Gather together all materials and line the base of the bin with paper towels
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STEP 2 - ADDING FRUIT
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- Cover the base of the bin with a layer of green / yellow lemons or other citrus fruit (unsprayed)
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STEP 3 - COLLECTION OF THRIPS
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- Collect greenhouse thrips from infested plants.
- Only collect leaves with thrips, to reduce the risk of introducing other insects and predators to the colony.
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- Look for the silvering appearance on leaves with faecal spots.
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- The thrips are slow moving and have white legs and wings.
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STEP 4 - ADDITION OF THRIPS
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- Place infested leaves on fruit and allow to dry (approx. 7 days).
- As the leaves dry the thrips will transfer onto the fruit.
Note: The more thrips you add the sooner you will be ready to release your parasitoids.
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STEP 5 - PUTTING ON THE LID
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Two options:
- Fine mesh netting held on with a tight elastic band.
- Matching bin lid with a hole cut out of the centre placed over netting.
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- In humid regions the netting lid is fine.
- In low humidity areas the bin lid helps retain moisture to stop the lemons from drying out.
STEP 6 - REMOVAL OF LEAVES
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- Once the leaves are dry and all thrips have transferred to the fruit, remove the old leaves before they start to decay.
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STEP 7 - INTRODUCTION OF THRIPOBIUS
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- When the greenhouse thrips have reached large numbers it is time to introduce Thripobius.
- These can be ordered from HortResearch for $20 (includes postage and rearing costs).
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STEP 8 - ADDITION OF THRIPOBIUS
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- The parasitoids arrive as pupae and should be added to the colony immediately.
- Open the lid of the tube and attach to the side of the bin with blue-tack.
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THRIPOBIUS EMERGENCE
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- Emergence will occur over the next 14 days.
- The adult wasps will start to parasitise the small thrips larvae immediately.
- When the parasitoids emerge they leave behind their black coloured pupal case.
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STEP 9 - CHECKING FOR THRIPOBIUS
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- After about 20 days check the lemons for Thripobius pupae.
- Found mostly on the base or between touching fruit.
- Place the lemons back with the pupae facing up to avoid squashing them.
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STEP 10 - SAVING A FEW THRIPOBIUS FOR THE COLONY
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- Only 50 Thripobius pupae need to be kept and the rest can be released.
- A cluster of pupae about the size of a twenty-cent piece equals about 50.
- If you have lots of fruit with only a few pupae on them it would be best to keep these fruit and release the larger clusters.
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STEP 11 - RELEASING THRIPOBIUS
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- Release pupae attached to lemons.
- In citrus balance the lemon in the branches.
- If you have lots of fruit with only a few pupae on them it would be best to keep these fruit and release the larger clusters.
- For avocados it may be necessary to nail the fruit to the tree as shown in the photo.
- Only release pupae that have not emerged.
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EMERGED AND NOT EMERGED THRIPOBIUS PUPAE :
HOW TO TELL THE DIFFERENCE
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Gently brush pupae with the fine artist's brush:
- If the pupae come off as solid individual black cylinders they have not emerged.
- If they flake into lots of small pieces they have already emerged.
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STEP 12 - SELECTING THE RELEASE SITE
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- Spread the parasitoids evenly through the orchard. Start with blocks or trees with a history of bad greenhouse thrips damage.
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STEP 13 - COLONY MAINTENANCE
- Restock the thrips after a release and when numbers get low.
- Remove diseased lemons.
- Brush pupae (not emerged) off dry lemons before removing.
- You can keep your colony going permanently if wanted, but will have to move it inside the house over winter to keep it warm.
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See also: Lifecycle of Greenhouse Thrips and Thripobius
If you require more information, please contact:
Karyn Froud, Scientist
HortResearch Mt Albert
120 Mt Albert Road
Private Bag 92 169
AUCKLAND, NZ
Tel: (09) 815 4200 Fax: (09) 815 4201
kfroud@hortresearch.co.nz
Mobile: 021 653 215
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