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Release rates and strategies
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| Introduction | |
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Trichogrammatoidea cryptophlebiae are used inoculatively, that is, relatively small numbers of wasps are released per hectare per release - their numbers increasing within the crop as the moth egg pressure increases. Releases of 1,000 wasps per hectare are made for 6 to 10 consecutive weeks starting from early November to late December depending on the location. The aim of this strategy is to parasitise some of the early laid eggs which may be below the level picked up in a standard monitoring check. One egg in 500 nuts is enough for Trichogramma to get started. When eggs start showing up in monitoring checks some of these are likely to be parasitised and are able to increase very quickly when the egg pressure rises. In this way sprays are likely to be saved. If you wait until moth eggs are showing up in numbers before starting releases then it may be several weeks before parasitism rates are high enough to consider not spraying. |
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| Method of release | |
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The Trichogramma are dispatched as parasitised MNB eggs on strips of finely corrugated card. There are over 100 parasitised eggs per strip. They are sold by the thousand or 10 strips for $25 to $30 depending on quantity. Staple the strips to a leaf around head height in areas where MNB have been observed; in areas where you expect moths to move into the orchard (e.g. from a rainforest gully, windward side etc.) and areas where you've had a problem in the past. See "Method of Release" and "Prices" for more details. |
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| In macadamias: | |
| Start releases early November in north Qld and Bundaberg, late November in Gympie, early December in Glasshouse, mid December for Northern NSW and late December/early January at Nambucca Heads.
Release 1,000 per hectare per week for at least 6 consecutive weeks. Start releases 2 to 3 weeks before anticipated jump in nutborer activity. Start earlier and go for more weeks if you want to cover 2 nutborer generations. For blocks up to 5 hectares, order enough for the total area you want the wasps to be active in. Initially, place all the strips in known hot spots, then when eggs are found more widely release through the block. For example, the block may be 5 hectares so order 5,000 per week but initially (first 2 or 3 weeks) all the cards can be placed in known hot spots or boundaries which may only total 0.5 hectare. This also reduces the total time to place the cards. Larger areas can be treated economically by ordering for about half the total area and concentrating the release in the most susceptible areas. The wasps will disperse over time. When eggs start showing up in the hots spots start putting the cards out more widely. This strategy will increase the chances of catching MNB eggs as they start to be laid in the pressure spots. If releases start late, then higher rates per hectare can be made over 2 or 3 weeks. |
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| In lychees: | |
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Start releases in late October/early November for North & Central Qld, late November in Southern Qld and mid December for Northern NSW or after fruit spotting bug sprays. Release 1,000 per week per hectare for 8 weeks but initially concentrate releases in know hot spots or problem boundaries. For example, the block may be 5 hectares so order 5,000 per week but initially (e.g. first 2 or 3 weeks) all the cards can be placed in known hot spots or boundaries which may only total 0.5 hectare. This also reduces the total time to place the cards. It takes about half an hour to staple 50 cards. When eggs start showing up in the hots spots start putting the cards out more widely. This strategy will increase the chances of catching MNB eggs as they start to be laid in the pressure spots.
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| Added benefits | |
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Remember that the wasps keep working through nut hardening in macadamias and through and beyond harvest in lychees right to winter if eggs are being laid. Indications are that this late activity has a significant impact on the over wintering moth population and thereby reducing the pressure the following season. |
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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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