Abstract: Newly molted male and female 5th-instar larvae of gypsy moth, Lymantria dispar, were separately infected with a LDMNPV suspension of known concentration: 1.3× 10⁴-10⁶ PIB,/ml.The experimental results demonstrated that sublethal doses of LDMNPV not only caused dif ferent mortalities of male and female larvae,but also affected their pupal number and sex ratio which was in favor of male. The EM pictures of ultrasection showed that fat body,trachea, ganglia, brain, ovary and prothoracic gland of female moth were infected by LDMNPV. Little data about brain, ovary and prothorcic gland infected by NPV is available. Polyhedra existed in nuclei of infected cells display strong reaction with antibody of LDMNP using immunogold-labelled technique.

Key words: Lymantria dispar&mdash, &mdash, LDMNPV&mdash, &mdash, sex ratio