Possibility of Evolution in Culture of the &amp;lt;i&amp;gt;Oryctes&amp;lt;/i&amp;gt; Nudivirus of the Coconut Rhinoceros Beetle &amp;lt;i&amp;gt;Oryctes rhinoceros&amp;lt;/i&amp;gt; (Coleoptera: Scarabaeidae: Dynastinae)

Geoffrey O Bedford

doi:10.4236/ae.2018.61004

Abstract

It is suggested that the isolates of Oryctes Nudivirus (OrNV), cultured for decades in cells of Heteronychus arator (F.) (HA), be checked to verify genomic changes have not occurred which adapt them to culture but reduce or cancel their ability to infect the target pest, the coconut rhinoceros beetle (CRB), Oryctes rhinoceros (L.). Full genomes of field-caught OrNV isolates, and their infectivity against larvae and adults, could be compared with those of HA-cultured isolates. Further data to correlate OrNV dosage indices with doses in number of virions/ml could be advantageous so as to explore if CRB larvae or adults may resist infection by a sub-threshold dose. Also the possibility of changes in the HA culture cells which alter the outer coat of the resulting virion, hence perhaps its infectivity towards CRB cells, could be checked. Might it be possible to move beyond HA-culture and develop tissue culture of Oryctes rhinoceros cells for mass production of OrNV as this beetle species is the target? Nuclear genomes of OrNV-resistant and OrNV-susceptible strains of the CRB could be examined for changes perhaps correlated with resistance. The possibility of endosymbiotic bacteria affecting CRB susceptibility to OrNV might be checked.

Highlights

It is suggested that the isolates of Oryctes Nudivirus (OrNV), cultured for decades in cells of Heteronychus arator (F.) (HA), be checked to verify genomic changes have not occurred which adapt them to culture but reduce or cancel their ability to infect the target pest, the coconut rhinoceros beetle (CRB), Oryctes rhinoceros (L.)
Might it be possible to move beyond HA-culture and develop tissue culture of Oryctes rhinoceros cells for mass production of OrNV as this beetle species is the target? Nuclear genomes of OrNV-resistant and OrNV-susceptible strains of the CRB could be examined for changes perhaps correlated with resistance
It would be worthwhile to compare the full genome of OrNV isolates freshly extracted from field populations of O. rhinoceros, with full genomes of OrNV long cultured in HA, to look for changes

Summary

Introduction

Young oil palms are attacked and may be killed While it is endemic in Asia, the pest had been accidentally introduced into the South Pacific in the early 20th century, and had spread and become established in a number of South Pacific countries (summarised in [1] [2]). The OrNV virion is the infective unit which must survive in the environment and be transmitted naturally or by artificial dosages [1] [2] [8] It is rod-shaped, with a viral membrane and capsid [8] enclosing a circular double-stranded DNA molecule for which the sequence of 127,615 bp (base-pairs) has been determined for a Malaysian isolate (Ma07 = Type B) [9]. It is a commentary rather than giving new data

Commentary and Discussion

Conclusion