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Monitoring for parasitism by Trichogramma carverae
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Pre Release Monitoring Pheromone traps or port wine traps for LBAM (4.1 ratio of water to port wine) should be in place at least three weeks before the expected moth flight. Moth catches should be noted at least weekly. Degree day models, where available, are another useful tool for prediction of moth flights. |
 Photo: SARDI Female LBAM adult (left), male (right) |
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Introduction to Monitoring for parasitism In vines, monitoring for parasitism in LBAM eggs can be done by inspecting leaves and looking for LBAM egg masses. Any leaves found with unparasitised egg masses can either be removed or tagged and inspected in a few days to see whether the eggs go black. In vines, LBAM usually lay their eggs on the tops of leaves often in a crease in the leaf. They are fairly easy to spot once you get your eye in. Typically up to 1,000 leaves are inspected per block. The leaves are not touched unless something looks like an egg mass. A counter is used, and the leaves are scanned quickly, with 50 leaves at 20 sites viewed within the block. More. |
 A counter makes the task easier |
| In pome fruit, it is much more difficult and not practical to monitor for parasitism. Larvae counts and strikes on fruit can be measured during the season. In this case Trichogramma are a component in an IPM program which likely includes Isomate® pheromone mating disruption and the wasps are used in pressure spots or boundaries. |
 A good hand lens in essential for monitoring. |
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LBAM flight times Trichogramma releases should be made at the beginning of the egg laying period. The first major moth flight occurs from September to November. The warmer regions producing the earlier flights. Larvae produced from this flight will be present around flowering and can cause significant damage to flowers and young fruit and facilitates early infection with bunch rots. The second moth flight occurs 6 to 8 weeks after the first flight. Larvae resulting from this flight can move into bunches before bunch closure where they are then very difficult to control with sprays. The autumn flight produces larvae coming into winter. These larvae feed on weeds through the winter and then pupate in late winter/early spring producing moths several weeks later in spring. Large larvae found in early spring are from this earlier autumn flight. They may crawl off the weeds (cape weed, clover, dock etc) and up onto the vines at budburst especially if herbicides are used to kill off under vine weeds. See LBAM flight table. |
Pheromone trap |
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Pheromone traps Traps should be placed in the crop in the spring, a few weeks earlier than the usual moth appearance. The pheromone buds need to be replaced every five weeks. The buds should be replaced in a rotation, that is not all at the same time as a fresh bud may attract more moths than an old one and can give a false impression of moth increases. Traps should be cleared every week and catches recorded. Moth flights are usually followed by a peak in an egg lay about one to two weeks later and then a peak in larvae hatch another 1 to 2 weeks later. Trap catches may range from zero to 80+ moths per week. Trap catches over 10 per week are likely to result in an egg lay that will require action of some sort. |
Fresh pheromone bud and sticky base |
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Monitoring for LBAM egg masses and parasitism Remembering that each egg mass may contain 50 or more eggs. Twenty egg masses found per 1,000 leaves represents a very high egg lay. Leaves with egg masses can be marked with a tag and dated. You can then return to these tagged masses and observe whether they are parasitised by wasps (gone or going black) or if they remain unparasitised (going yellow green to brown) or have produced grubs (only the clear shells remain and grubs found nearby). Alternatively, any leaves with egg masses can be removed and kept in a warm humid place for a few days to see if the eggs go black. This may be more convenient but tends to underestimate parasitism rates as freshish eggs have more chance of being parasitised if left in the field until brown. Trichogramma releases |
 Freshly laid LBAM egg mass
The same egg mass, about 5 days later, showing black parasitised eggs.
LBAM larva |
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Trichogramma carverae are produced by Bugs for Bugs
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Sales enquiries contact BioResources Pty Ltd
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Phone (07) 3289 4919 email: richard@bioresources.com.au
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