Yeap! there is such a 'biological control' for whitefly, and like
most of these control measures is idea for the protected environment
of the glasshouse. we have used it both here at writtle college and
at the last university i was at. and it works. however, one point to
note, as with most of these 'friendly' organisms, they need the host
to survive. obvious point i know, but bear in mind either a small
'background' population of the whitefly (in this case) is required
for the survival of E.formosa, or else it to will die out, thus
allowing whitefly to repopulate IF introduced back into the
glasshouse.
good luck, and don't spray for other pests unless you know its user
friendly toward the E.formosa!
dave morpeth