A nucleopolyhedrovirus isolated from the beet armyworm Spodoptera exigua (Polish laboratory culture), SeMNPV (P), morphologically similar to the viral bioinsecticide virus Spod-XR, was characterized molecularly and biologically. Phylogenetic analysis based on three conserved baculovirus genes, polh, lef-8 and pif-2, showed the highest homology of SeMNPV (P) to Mamestra brassicae (Mb) MNPV and M. configurata (Maco) MNPV, and much less to SeMNPV (Spod-XR). These findings were confirmed by genomic DNA restriction profile analyses. Bioassays revealed that SeMNPV isolated from the commercial bioinsecticide Spod-XR was themost infectious for S. exigua, while the infectivity of SeMNPV (P) and MbMNPV was significantly lower. These data suggest that SeMNPV (P) is a variant of MbMNPV.
In 1993–1997 the occurrence of Lepidoptera pests: Pieris rapae L., Pieris brassicae L., Mamestra brassicae L., and Plusia gamma L. were observed on the nine different late cabbage vegetables; Savoy cabbage cv. Vertus, white cabbage cv. Amager, red cabbage cv. Langendijker, brussel sprouts cv. Maczuga, cauliflower cv. Pionier, blue kohlrabi cv. Masłowa, white kohlrabi cv. Delikates, kale cv. Zielony Kędzierzawy and broccoli cv. Piast. The field observations showed that butterflies differentiated among host-species for oviposition. The butterfly females of all species preferred for oviposition the brussel sprouts and deposited a substantially larger number of eggs on leav es of them. Plant species with green leaves were more preferred than the red leaf ones.