What to expect after releasing Trichogramma

The wasps will disperse from the cards and go in search of MNB eggs to parasitise. Dispersal is slower in the dense foliage of a mature plantation than in a moderate spaced younger crop.

As mentioned in strategies the object of the regular release is to get some of the early laid eggs parasitised. This is difficult to measure at the time and not practical. Experience over the last few years in trial sites and commercial releases has shown that this does happen so that when eggs are more easily found (1 or 2 per 100 nuts) some of these are usually parasitised.

Monitoring for MNB and Trichogramma takes some practice so if you don't have the time to learn and do it yourself, we suggest you employ a crop scout. Finding moderate to high levels of parasitism can save a lot of spraying and easily covers the cost of the crop consultant.

Fresh MNB egg

As Trichogramma build up in a crop there are various tell-tale signs that will alert the crop scout. Firstly, the appearance of black eggs and then black eggs with escape holes. Corresponding with the increase in the black eggs will be a decline in the number of hatched viable eggs.

However, many eggs found while monitoring may be parasitised but have not had time to go black which takes about 5 days. "Not black" eggs should be collected and grown out to see if they go black (and not thrown on the ground wasting this useful information). This process will give a more accurate idea of parasitism.

Parasitised MNB egg with wasp escape holes

Trichogrammatoidea cryptophlebiae are produced by BioResources Pty Ltd ABN 12 078 989 081

Phone (07) 3289 4919 Email: richard@bioresources.com.au