Trichogramma carverae - Release rates and strategies

Release rates and strategies


Summary
	LBAM in Grape Vines	Codling in Pome Fruit	LBAM in blueberries
Pre release monitoring	Historical records Pheromone traps Port Wine traps Eggs counts	Historical records Pheromone traps	Historical records Pheromone traps Port Wine traps Eggs counts
Timing of releases	During major moth flights	During major moth flights	During major moth flights
Methods of release	Capsules, Loose eggs	Capsules, Loose eggs	Capsules
Release rates	2 x 60 caps/ha/major flight	2 x 60 caps/ha/major flight	2 x 60 caps/ha/major flight
Isomate treated crops	Treat boundaries & hot spots	Treat boundaries & hot spots	Treat boundaries & hot spots
Post Release Monitoring	Larvae counts Parasitised eggs counts	Stings Larvae counts	Larvae counts Parasitised eggs counts
Integrated Pest Management	In conjunction with Isomate®, B.t., Mimic®	In conjunction with Isomate®, B.t., Mimic®	In conjunction with B.t., Mimic®

LBAM in Grape Vines

Seasonal Behaviour of Lightbrown Apple Moth
Lightbrown apple moth is tolerant of low temperatures and remains active at a low level during winter, responding to increasing temperatures in the spring with a distinct moth flight and an egg laying peak approximately one week later. The first major moth flight appears roughly the same time each year for a given district. This is followed by another generation six to eight weeks later and so on depending on temperature.

The importance of each generation to the grower will vary from crop to crop and area to area.

Lightbrown apple moth larvae can be controlled with conventional insecticides but the broad emergence peaks make accurate timing of sprays difficult.

Well developed larvae within leaf rolls, between fruit in clusters and in grape bunches are protected from contact with chemicals. High levels of control are often possible only with repeated applications of insecticide.

The biological insecticide Bacillus thuringiensis requires accurate timing because of its specificity for very small larvae and its short field life.

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.

The table below is a guideline only:

District	1st	2nd	3rd	4th
North Coast NSW	Aug	Oct	Dec	Mar-Apr
Cobram/Shepparton	Early Sept	Early Dec	Mid Jan
Sunraysia	Mid Sept	Mid Nov	Jan	April
Harcourt	Mid Sept	Late Nov	Jan	Mar-Apr
Yarra Valley	Sept-Oct	Late Nov-Early Dec	Feb	Apr
Mornington Peninsular	Late Sept	Late Dec	Feb	Mar-Apr
Coonawarra	Oct	Early Nov	Dec	Jan
Launceston	Nov	Mar-Apr
Huon Valley	Nov	Mar-Apr
Batlow	Late Nov	Late Dec	Early Feb	Late Mar

Breaking the Cycle of Chemical Use In districts with cool winters, natural populations of Trichogramma are usually slow to increase in spring. Their activity will be further limited if applications of chemical insecticides are made. This locks the grower into a cycle of chemical use because Trichogramma and other beneficial insect species do not get an opportunity to increase to useful levels. The introduction of mass reared Trichogramma can break this cycle of dependence on chemical insecticides by boosting Trichogramma numbers at critical times during the season when they will have the maximum effect on lightbrown apple moth development.
Trichogramma species for Tree and Vine Crops The species selected for use against lightbrown apple moth is Trichogramma carverae. Field trials in grapes, apples and citrus have clearly demonstrated that this species has the ability to find and parasitise lightbrown apple moth egg masses in dense foliage and tree tops.
Pre Release Monitoring Approximate peaks in moth flights for various districts are listed in the table. This is a guide only, as peak flights may occur two weeks either side of the norm. If past records for your property are available these will be useful in determining the best time for Trichogramma releases. LBAM pheromone traps or port wine traps (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.
Timing of Releases Releases of Trichogramma during the early stages of a moth flight will ensure a plentiful source of host eggs for the wasps and will enable a carry over of wasps for the next month or longer. For districts that have two or more distinct peaks in LBAM flights, it is recommended that a release be made in the early stages of each of these flights.
Methods of Release Trichogramma wasps are delivered in the form of parasitised grain moth eggs enclosed in small cardboard capsules. These are designed to be stapled to foliage and distributed evenly through the crop. The capsules provide the parasitised eggs with some protection from general predators like ants and beetles which are common in orchards and vineyards. The capsules also provide protection form rain and irrigation. For larger areas, loose parasitised eggs can be distributed in special liquid mixture via specialised dosing equipment. See "Methods" for more details.
Release Rates Field trials* have shown that a release rate of 120,000 parasitised moth eggs per hectare of vine or orchard crops is sufficient to achieve a moderate to high level of parasitism against LBAM throughout the release area. The recommended release rate for a moderate infestation is 120 capsules per hectare, with each capsule yielding over 1,000 wasps. Two releases of 60 capsules per hectare a week apart is an alternative. A clear vial containing parasitised eggs is included with every package of Trichogramma. These wasps will emerge one day before the eggs in the capsules. The capsules should be placed in the crop when the first wasps emerge in the clear vial. See also "Delivery"
Crops Treated With Isomate Pheromone Mating Disruption Crops treated with Isomate for LBAM (apples or grapes) will benefit from Trichogramma releases around the borders and exposed areas. The perimeters of such crops are susceptible to the inward movement of mated female moths. The standard rate of 120 capsules (or 120,000 wasps) per hectare should be applied to a band 20 metres wide around the crop. Sources of LBAM adjacent to the Isomate treated areas should also be treated to reduce the risk of immigration of mated female moths. Trichogramma carverae also freely parasitise the eggs of oriental fruit moth and codling moth.
Post Release Monitoring In vines Trichogramma activity can be measured by collecting LBAM egg masses, keeping them in a warm place, and watching to see how many masses contain eggs that go black, i.e. that are parasitised. If the majority of egg masses are parasitised, and the pressure is not extreme, then further action is not usually required. The surviving larvae will be at the mercy of other beneficial species including larval parasites, lacewings and spiders. See "Monitoring" for details.
Integrated Pest Management The appropriate IPM program for LBAM or codling moth in a given crop is determined by many factors: moth pressure, variety, tolerance for damage, market requirements, and the philosophical approach of the fruitgrower. More on IPM. Depending on these factors, integrated programs incorporating Trichogramma may range from one or two releases at the base rate, through higher and more frequent release rates to combinations of Trichogramma and other compatible products such as Isomate, Bacillus thuringiensis or selective insecticides. Regardless of the program used, it is important to monitor flights of moths and subsequent larval infestation in the crop and if necessary intervene with a compatible larvicide while the larvae are small. See also "Chemicals".
Codling Moth in Pomefruit
Pome fruit treated with Isomate for LBAM and/or codling moth will benefit from Trichogramma releases around the borders, in hot spots and exposed areas. The perimeters of such crops are susceptible to the inward movement of mated female moths. The standard rate of 120 capsules (or 120,000 wasps) per hectare ( or 2 x 60 capsules a wekk apart) should be applied to a band 20 metres wide around the crop. Sources of moths adjacent to the Isomate treated areas should also be treated to reduce the risk of immigration of mated female moths.

Trichogramma carverae are produced by Bugs for Bugs

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