A Comparison of Four Wild Isolates of Heliothis Nuclear Polyhedrosis Virus

our Heliothis NPV isolates(two SNPV:HaS and HzS two MNPVs:HaMl and HaM2)were com-pared on the shape and structure,biological activity,structural polypeptide,restriction pattern andDNA homology.The LD50 values of the four isolates for late second to early third instar H.armigera larvae were 361,387,2633 and 3560 PIBs/g of diet;the LT50 valuse for 5×103 PIBs/g of diet were4.6,4.9,6.4 and 6.6 days respectively,Bioactivities of two SNPV isolates were higlier than that of two MNPV isolates.Assayed by SDS-PAGE,each polyhedrin of four isolates contained a singlepolypoptide.The structural polypeptides of HaM1 HaM2 comigated on SDS-gels,the strueturalpolypeptide maps of Has and HzS were similar,but there were little similarity between SNPV and MNPV structural polypeptides,Digested by BamHI、EcoRI、HindⅢ and XbaI,two MNPV genomes hadidentieal restriction patterns,and two SNPV genomes had similar fragmentation profiles,showing onlyslight difference in the number and size of several fragments.But SNPV and MNPV genomes had