silkworm,Bombyx mori

[mloonjin]

I want to know the detailed course about the form of ZZW triploid female silkworm by using hot water treament .I know the method summarily: the eggs were treated with hot water(46 centigrade,18min) immediately after oviposition(0~10min).this hot-water treatment causes the fusion of an ameiotic femal pronucleus,2n(ZW),with a male pronucleus n(Z).

but I have some question.I think the oocyte is haploid,but why it is the 2n(ZW).
the oocyte should be haploid n(Z) OR n(w) after expel from its body.the fusion only form diploid.Who can tell me why?thank you in advance.