Nucleopolyhedroviruses (NPVs) are naturally occurring entomopathogens that show promise as bioinsecticides against pest caterpillars. Determining the potential of a NPV as an insecticide requires conducting many laboratory assays. These experiments typically require a large number of larvae and it may be necessary to collect eggs from laboratory or wild sources for several days before an adequate supply is obtained. Fortunately, in many species of Lepidoptera, it is possible to synchronize rearing by storing eggs at 4°C.
Cabbage loopers (Trichoplusia ni Hübner) are widespread, highly destructive agricultural pests. Preliminary trials suggest that the single (S) nucleocapsid nucleopolyhedrovirus of cabbage loopers (TnSNPV) might be effective in controlling cabbage loopers (Jaques 1977); however, many additional studies are required before it can be commercially developed as a bioinsecticide.