Trichogrammatoidea cryptophlebiae dubbed MacTrix are members of a group of egg parasitoids that lay their eggs into moth eggs and in so doing prevent the development of caterpillars. See the lifecycle diagram below.
MacTrix parasitised macadamia nutborer eggs and are supplied as "black" parasitised eggs on finely corrugated card. The cards are stapled to a leaf, initially in known hot spots and then more widely through the crop. The wasps emerge from the black eggs about a day later - 2 or 3 wasps from each egg. The wasps mate and the females go in search of nutborer eggs to lay their own eggs into.
MacTrix are a very effective parasitioid able to hunt through dense foliage and into the tops of trees. Parasitism rates are often high with spraying significantly reduced. There are also indications that good Trichogramma activity reduces the pressure in the following season.
Macadamia nut, lychee, longan.
Crops with typically moderate to high levels of MNB (which are sprayed once or more each season) will benefit the most from releases of Trichogramma (compared to crops where MNB only occasionally require spraying in a typical season). T. cryptophlebiae is a very effective parasitoid - able to find nutborer eggs in dense high trees and commonly achieving very high levels of parasitism.
Macadamia nutborer also feeds on a number of common plants including Bauhinia, Bird of Paradise Tree, Cupania, Easter Cassia, Golden Raintree, Minosa Bush, Poinciana, Scotia, Tamarind and Mangroves. These plants may contribute to the over wintering of nutborer and subsequent movement of moths into the plantation but they are also suitable sites to release the Trichogramma wasps.
How it works
Trichogramma are tiny wasps, less than 0.5 mm, which lay their eggs into moth eggs. The wasp larva develops into a fully formed wasp inside the moth egg in the process killing the developing caterpillar.
The wasps emerge through tiny escape holes but the eggs remain black. Wasps emerge from the moth egg instead of a caterpillar.
Trichogrammatoidea cryptophlebiae are used inoculatively, that is, relatively small numbers of wasps are released per hectare. Releases of 1,000 wasps per hectare are made for 6 consecutive weeks starting from mid November to mid December depending on the location.
The aim of this approach is to catch an early egg lay so that when the main flight occurs the wasp will be present in low numbers from which they can increase very quickly.
The wasps are very focused on finding eggs in the crop and over several weeks their numbers can increase greatly. High levels of parasitism, over 80%, are common.
Sprays for nutborer are typically reduced and sometimes not required.
Further, the wasps keep working through nut hardening into winter which may have an impact on the over wintering moth population and thereby reduce the pressure the following season.
The wasps are supplied as parasitised moth eggs on finely corrugated card. Each card yields 50 - 100+ wasps. About 12 - 24 cards are placed per hectare per application.
Release sites within the crop are selected on the basis of monitoring data or the history of the block - where nutborer are usually a problem.
The wasps emerge about 3 days after dispatch from the insectary.
The 2004-5 season was the first season where good quantities of Trichogramma were available and about 350 ha were treated. By the 2011-12 season the treated area has risen to over 4,000 hectares.
These figures underestimate the actual number of hectares to benefit from the releases as they disperse over time and if released at one end of a large plantation they will move through the entire plantation as do the nutborer.
Research into the development of mass rearing systems for this wasp has been assisted by the Australian Macadamia Society and in conjunction with NSW Agriculture Alstonville under an IPM research project supported by HAL.
Near fresh nutborer egg
"Black" parasitised nutborer egg after wasps have emerged through the escape holes
MacTrix release cards are stapled to a leaf
MacTrix female soon after emerging from a parasitised egg.