Observations on the Peritrophic Membrane of Tortricid and Noctuid Insects and its Role in Susceptibility and Enhancement

Abstract Although stilbene fluorecent brighteners have been demonstrated to increase the susceptibilities of many lepidopterous insects to insect viruses, little information exists on the effects of a brightener on the susceptibility of the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae) and the false codling moth, Cryptophlebia leucotreta Meyrick (Lepidoptera: Tortricidae). In the present study, we tested the effects of the fluorescent brightener 28 (UNPA-GX) on increasing of the insects' susceptibility to a granuloviruses. The bioassay tests showed that brightener did not increase the susceptibility of codling moth neonate larvae and false codling moth larvae to the granulovirus (CpGV). The same result was obtained when the false codling moth GV was tested in presence of brightener against its homologous host. In addition, brightener failed to change the susceptibility of the codling moth to ClGV. In histological sections from the codling moth's midgut, the peritrophic membrane (PM) was fo...