Suitable hosts for Trichogramma pretiosum

Access to suitable hosts and food sources leading into and coming out of winter are likely to be important for Trichogramma survival in numbers which will enable a rapid build up in spring when temperatures and pest pressures increase.

Sampling in the Lockyer Valley revealed a wide host range for T. pretiosum:

Notes:

* Collections made by Larry Hooper, DPI Redlands Research Station.

**T. pretiosum is a know parasitoid of potato tuber moth (Kfir) although no work has been done in the field in Australia.

Cluster caterpillar (Spodoptera litura) is not readily parasitised by Trichogramma spp., due to the barrier that is formed by the moth scale covering the egg raft. Some eggs around the edges may be parasitised

Cabbage white butterfly, Pieris rapae, is also unsuitable for pretiosum as it has a relatively large egg with a hard shell. There are reports of other Australian species parasitising this egg (McLaren).

There are no doubt other hosts for Trichogrammatids that are of low or no economic significance which may serve to maintain the wasps at useful levels during periods of low pest egg pressure. Non crop vegetation may also be important. For instance,various weeds including sow thistle are important hosts for heliothis.