Crops Suitable for Release

Macadamia, longan and lychee are all attacked by macadamia nutborer and are suitable for MacTrix release. Both small and large farms are equally suitable for MacTrix release, however, crops with moderate to high levels of macadamia nutborer will benefit the most from releases of Trichogramma, compared to crops with low levels of macadamia nutborer.

Macadamia nutborer also feed on many common plants, including Bauhinia, Bird of Paradise Tree, Cupania, Easter Cassia, Golden Raintree, Mimosa Bush, Poinciana, Schotia, Tamarind and mangroves. These plants may contribute to the over wintering of macadamia nutborer and subsequent movement of moths into the plantation. These plants are suitable sites to release MacTrix.

Release Rates and Strategies

MacTrix are used inoculatively, that is, relatively small numbers of wasps are released per hectare. The aim of this approach is to catch an early egg lay so that when the main nutborer flight occurs the wasp will be present in low numbers from which they can increase very quickly. One macadamia nutborer egg per 500 nuts is enough for MacTrix to get started. If you wait until nutborer eggs are showing up in your regular monitoring checks before releasing MacTrix it may be several weeks before parasitism rates can catch up, by which time nutborer can do a lot of damage.

We recommend doing weekly releases for 8 to 12 weeks, starting several weeks before macadamia nutborer are typically observed. Smaller crops (up to 5 Ha) require a higher release rate per hectare of 500 to 1000 per hectare per release. Larger properties can significantly reduce this rate if the cards are placed judiciously in areas where the nutborer first show up or in historical hotspots. If you want to cover two macadamia nutborer generations you should start MacTrix releases earlier and release for a longer period.

Releases of MacTrix should begin during the following times in macadamias:

• Early November in north QLD and Bundaberg
• Late November in Gympie
• Early December in Glasshouse Mountains
• Early December in northern NSW
• Mid December in Nambucca Heads

Releases of MacTrix should begin during the following times in lychees & longans:

• Late October/early November in north & central QLD
• Early November in southern QLD
• Early December in northern NSW

If MacTrix releases start late, then higher rates per hectare can be made over 2 or 3 weeks.

Chemical Use and MacTrix

MacTrix are adversely affected by many chemical insecticides and some fungicides, however, some sprays are more disruptive to MacTrix than others. There are a number of ‘safe’ and ‘moderately hazardous’ chemicals that can be used with MacTrix (see table below). Prodigee® is safe for MacTrix and other beneficials and is registered for use in macadamias and lychees, meaning that it can be used in conjunction with MacTrix when macadamia nutborer pressure is too high.

Insecticides sprayed in quick succession for fruit spotting bug and macadamia nutborer are particularly disruptive to MacTrix, and other beneficial insects. Any chemical residues will need to have had time to disperse before MacTrix releases are made. A weeks wait is enough for most chemicals and more than necessary for fungicides. If releases have been going for some time and it is deemed necessary to spray for fruit spotting bug then you should do so. Adult MacTrix will be killed but wasps developing inside nutborer eggs will have a good chance of survival and will be able to re-establish quickly.

Chemical use should always be discussed with your crop consultant.

Summary of data collected by Huwer & Maddox, Alstonville, NSW DPI

Ordering and Delivery

MacTrix need to be ordered several months in advance so we can get our colony to the necessary capacity in time. They are sold by the 1,000 parasitised eggs (2 or 3 wasps emerge from each egg).

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 50,000 may comprise 25 sheets of higher egg density cards. High density cards can be cut in half by the grower if more release points are desired.

MacTrix are usually despatched on a Tuesday via Australia Post Express Post, to arrive on Wednesday or Thursday. Upon despatch, we send an email notification and tracking number for your parcel. They are delivered as ‘black’ parasitised eggs on corrugated card. Each sheet is 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.

When you receive the cards there will be a day or two before the wasps emerge. Please ensure that the package is not left in a hot place, especially in direct sunlight or in a closed car! A note will be included in the package with the estimated time of emergence based on a constant temperature of 25°C, however, temperature in transit and at your end may vary from 25°C. If it’s hotter they will come out earlier and if its colder, later.

If MacTrix are placed in the field immediately on arrival, it may be several days before they emerge and some MacTrix 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, or when, for example 50 of the wasps have emerged within the bag. This will minimise predation. If you keep emerged wasps in the bag for more than a day or so they will need some food. You can streak a very little bit of honey on the inside of the bag. Fresh air should also be allowed into the bag upon arrival and then the bag resealed.

Stalling Wasp Emergence

If wasps start emerging earlier than you expect or if the weather is unsuitable for placement in the field, MacTrix development can be slowed by placing them in a cool room (between 8 and 14°C) or in an esky with a couple of ice bricks. This will slow the development of the wasps and delay their emergence. Do not refrigerate for more than 4 days because their fitness will decline. Note, a household frighted is a bit too cold.

How and Where to Release

MacTrix cards are stapled onto either the upper or under-side of tree leaves at about head height, preferably not in direct sunlight if temperatures are extremely hot. If severe rain is predicted it is best to staple cards within an upturned plastic takeaway cup so they are that are more protected. 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.

Initially, MacTrix should be released in known hot spots or boundaries and later (once nutborer eggs start showing up in hot spots) they can be released more widely through the crop in areas where you expect moths (i.e. from a rainforest gully, windward side etc).

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.

Contact BioResources or your consultant to determine a release rate and program suitable for your far.

After Release and Monitoring

MacTrix will disperse from the cards and search for nutborer eggs to parasitise. Dispersal is slower in the dense foliage of a mature plantation than in a moderately spaced younger crop.

As MacTrix build up in a crop there are various tell-tale signs that it is reducing your nutborer population. Firstly, the appearance of black nutborer eggs and secondly black eggs with escape holes will correspond with a decline in unparasitised nutborer eggs. However, many eggs found whilst monitoring may be parasitised but have not had time to go black (this takes about 5 days). It is important to collect these nuts and monitor them to see if they turn black or not (nuts can be placed, for example, in egg cartons to stop them rolling around and squashing the eggs, and the egg carton can be kept in a sealed box in case nutborer larvae emerge).

Monitoring procedures for macadamia nutborer is described in the ‘Macadamia grower’s handbook’. Typically, sampling for nutborer/MacTrix is done by removing 100 to 320 nuts from trees (e.g. 10 nuts from 32 trees) and examining them for nutborer eggs. Any eggs found are recorded and scored as either: fresh, red, hatched, black or black with escape holes. Nuts are also checked for damage, and any larvae and their size are recorded. This sampling is done fortnightly (or weekly during pressure periods) and gives a very good picture of what is going on when compared with results from previous weeks.

Monitoring for nutborer and MacTrix takes practice, so if you don’t have time we suggest you employ a crop consultant. Finding moderate to high levels of parasitism by MacTrix can save a lot of spraying and easily covers the cost of a consultant.

Cultural Practices to Aid Establishment

MacTrix wasps perform best in moderately warm temperatures (20-32°C) without extreme rain or wind. Several days of extreme heat will reduce MacTrix activity, especially if the crop is water stressed and the air is dry. However, extreme weather events often only mean a short delay in MacTrix activity whilst they shelter in micro-habitats until environmental conditions improve.

Like all hymenopteran parasitoids, MacTrix drink nectar to give them fluids and energy to search and parasitise insect eggs. However, being very small, even minute amounts of plant sugars, nectar or honey dews enable them to survive and lay eggs. They will live longer and be more fecund if there are more resources available. Crop environments can often be quite barren in terms of floral resources and alternate hosts for our ‘good bugs’, simply because there often aren’t many other plant species other than the crop itself. Leaving vegetation ‘strips’ to grow out within the inter-row can be a small step that can bring about a well-functioning ecosystem of invertebrates, and provide nectar and pollen for biological control agents at the same time. Planting cover crops within the inter-row can further enhance beneficial activity within your crop.