Preliminary Testing of some New Release Methods for Egg Parasitoid Trichogramma spp.

Preliminary investigations were conducted in laboratory cages to test the efficiency of a novel release technique for egg parasitoid Trichogramma species and this was compared with the traditional techniques. The efficiency of the techniques was determined based on time taken for release, adult emergence and percentage egg parasitism. Mixing of eggs with carriers like talc (1:1 ratio) and agar solution (0.1%) recorded least time for application. Spraying of loose parasitised eggs mixed with agar solution was considered as the best treatment amongst the treatments where aqueous solutions were used as carriers. In treatments where loose parasitised eggs were mixed with various solid and aqueous carriers, per cent emergence was low ranging from 40.5 to 57.1% compared to 95.0 to 100.0% in release of adults, Tricho bit, Tricho capsules and loose eggs without any carrier. The lowest emergence was recorded when loose parasitised eggs were mixed with talc. Adult release, sprinkling of loose parasitised eggs mixed with vermiculite and semolina gave significantly higher parasitism compared to the other techniques of release. The results indicated that release of Trichogramma can also be tried by mixing with a spray solution (for eg. agar solution) with modification of sprayer nozzle or with solid carriers (for eg. vermiculite). Such techniques will be better understood by stakeholders and is expected to increase uptake of this important biological control agent.