Trichogramma are susceptible to many chemical insecticides and some fungicides.
Insecticides for fruit spotting bug and Bulldock® for nutborer are disruptive especially if sprays are made in quick succession.
There are however a number of "safe" and "moderately hazardous" products that can be used with Trichogramma.
Prodigee® targeting nutborer is safe to Trichogramma and other beneficials and is registered for use in macadamias and lychees so can be used in conjunction with Trichogramma when parasitism is low or MNB pressure too high.
Chemical use should be discussed with your crop consultant.
Bulldock® kills adult wasps and if used repeatedly will reduce wasps as well as the natural enemies of mealybug, scale and feltid coccid below useful levels. Spot spray where practical e.g. for FSB, feltid coccid.
When Trichogramma are well established, say 4 black eggs found per 100 eggs, then a spray of a "High" rated insecticide will reduce wasp numbers immediately but there will be sufficient numbers of wasps developing in parasitised eggs for their number to increase again in the following week or two. Repeated sprays in a short period will reduce wasp below useful levels.