Trichogramma pupae can be immersed in water for up to two hours without significant effect on the emergence of the wasps. By adding a special thickener the pupae can be kept in suspension with little agitation which enables the even dosing of the pupae onto the crop. This is done with an 8 ml soap pump, selected for its soft action which minimises damage to the trichogramma.
If you need to split up your consignment of loose pupae for different blocks, use the following as a guide:
There are about 50,000 pupae per gram. One gram equals around 3 mls by volume.
Using a finely graded beaker (a medicine glass is good) measure out the quantity of trichogramma that you wish to distribute in one mixing. For example: 5 hectares at 2 grams per hectare will require about 30 mls of Trichogramma.
How much to mix?
For manual dosing using the soap pump with a back pack, determine the size of the dose you wish to apply (e.g. 8 mls) and also how many doses per hectare. The more doses, the more even the distribution of the wasps will be. Use the table below to work out the approximate distance between doses. Adjust to suit your row spacing.
Determine how many mls of liquid are to be applied per hectare and then the total volume required,
e.g. 125 x 8 ml doses = 1 litre per ha.
Alternatively, for inoculative releases in field crops, you can reduce the distance travelled per hectare by going down rows about 20 m apart.
The thickener is very powerful. If too much is added the liquid will get too thick and clog the doser. So start by mixing 1.5 grams of thickener per litre of water (or by volume 3.5 mls of powder per litre). Add the quantity of Trichogramma you wish to distribute and mix in gently. The pupae will stay evenly distributed with a little agitation.
If you are using bore water the amount of thickener may have to be increased to near 2 grams per litre.
Add just enough thickener to keep the pupae in suspension.
Do not mix in more trichogramma than can be distributed in 2 hours.
Estimated time of emergence and the Indicator vial
The wasps will begin to emerge around the time stated on the label if kept at the temperature noted. If it's cooler, they will take longer to emerge and if warmer, will emerge more quickly. Its best to wait to about 24 hours before wasp emergence to apply loose pupae. This will minimise predation from ants in particular.
To help you with the timing the parcel will include a small clear "indicator vial" containing a sample of trichogramma pupae. The wasps in the vial will emerge about 24 hours before the bulk of loose pupae.
Delaying wasp emergence
If field conditions are unsuitable for release (raining or very windy), the trichogramma pupae and indicator vial can be stored in a domestic fridge for up to 3 days. Do not allow the fridge to drop below 3 degrees C.