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Method of Release
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| Release sheets and cards | |
| The Trichogramma are dispatched as parasitised nutborer eggs on sheets of finely corrugated cardboard 180 mm x 370 mm.. The sheets are perforated to enable them to be gently broken up into 24 individual cards each about 30 mm x 90 mm.
Before despatch the sheets are sorted into different egg densities so that parasitised eggs per sheet range from 500 to over 2,000. They are sold by the thousand parasitised eggs for $25 to $30 depending on quantity. Small orders are generally supplied with the low density sheets. For example, an order of 1,000 may be given 2 sheets or 48 individual cards. While an order of 20,000 may comprise 15 sheets of higher egg density cards. High density cards can be cut in half by the grower if more releases points are desired. The cards are stapled to a leaf about head height. An office type stapler can be used but we suggest you obtain a good plier type stapler especially if you have a big area to cover. When you receive the cards there will be a day or two before the wasps emerge. A note will be included in the package with the estimated time of emergence based on a constant temperature of 25˚C. |
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However, temperatures in transit and at your end may vary from 25˚C. If its hotter they will come out earlier and if its colder, later. If the Trichogramma are placed in the field on arrival, it may be several days before the wasps emerge and some Trichogramma pupae may be eaten by predators like ants before the wasps emerge. We suggest you place the cards in the field in the 24 hours leading up to wasp emergence. This will minimise predation. Alternatively, some strips can be placed in a glass jar on arrival. When a few wasps start coming out in the jar then place the cards in the field. |
 Close up of release card showing "black" parasitised nutborer eggs |
| Stalling wasp emergence | |
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If wasps start emerging earlier than you expect or if the weather is unsuitable for placement in the field, the Trichogramma can be slowed by placing them in a cool place. Wasp development is minimal below 12˚C. Place the Trichogramma in a fridge that runs between 5 and 14˚C or in an Esky with several ice bricks. Refridgeration should not exceed 4 days as wasp fitness will decline beyond this time. |
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More on predation
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If you inspect a card just after the wasps have emerged you should be able to see the tiny wasp escape holes in the eggs. The eggs remain black after the wasps have emerged. Sometimes ants will even eat the back empty egg shells left after the wasps have emerged, so if you find an old card with no eggs on it do not assume that the wasps were eaten before they had time to emerge.
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See also " Release rates and strategies"
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Trichogrammatoidea cryptophlebiae are produced by BioResources Pty Ltd ABN 12 078 989 081
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Phone (07) 3289 4919 Email: richard@bioresources.com.au
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