Abstract
Gorse spider mite, Tetranychus lintearius, was imported into New Zealand in 1988 for the biological control of gorse, Ulex europaeus. It has been released at 34 sites so far,, further widespread liberations are planned before the end of 1989. While in quarantine, a fungal pathogen, Verticillium lecanii, was isolated from the mites. Initial attempts to eliminate the disease, using 2% sodium hypochlorite to surface sterilize eggs and 5% to sterilise substrate gorse, resulted in 100% male mites in the next generation. A less rigorous method using 0.5% sodium hypochlorite followed by a sodium citrate wash successfully eliminated the disease without altering the normal sex ratio
