ENTOMOLOGY 135

INTRODUCTION TO BIOLOGICAL CONTROL

Biology of Insect Viruses

I. Virus terminology and structure

1. Nucleocapsid
2. Capsid
3. Virion
4. Shape of viruses

II. Baculoviruses - dsDNA

1. Nuclear polyhedrosis virus (NPV)
   1. Virus morphology
   2. Occlusion (= inclusion) body (polyhedrin)
      1. single-embedded virion (SEV)
      2. multiple-embedded virions (MEV)
      3. 0.5 to 15 microns; mean size = 2.0 microns
      4. 100 plus virions per occlusion body
      5. Polyhedral occlusion bodies (POB)
   3. Mode of infection
   4. Tissues infected (midgut, fat body, nerve, blood cells, etc)
   5. Signs and symptoms
   6. Period of lethal infection (4-10 days)
   7. Host range
2. Granulosis virus (GV)
   1. Virus morphology (like NPV)
   2. Occlusion body (granulin) = capsules
      1. One virion per occlusion body
      2. Like tiny granules; size =0.5 microns
   3. Tissues infected (midgut and fat body or all tissues)
   4. Signs and symptoms
   5. Period of lethal infection (3 days to 20+ days)
   6. Host range - restricted to Lepidoptera
3. Baculovirus of Oryctes (to be covered later)

III. Other viruses

• Cytoplasmic polyhedrosis virus -dsRNA
• Entomopoxvirus - dsDNA
• Iridescent virus -dsDNA

Selected References

• Adams, J. R. and Bonami, J. R.1991. Atlas of Invertebrate Viruses. CRC Press, Boca Raton, FL.
• Burges, H. D. 1981. Microbial Control of Pests and Plant Diseases 1970-1980. Academic Press, New York. chapters 5, 16-21.
• Granados, R. R. and B. A. Federici. (eds).1986. The Biology of Baculoviruses. Vol. 1 and Vol 2. CRC Press, Boca Raton, FL. Vol. 1: 275 pages and Vol. 2: 275 pages.
• Tanada, Y. and H. K. Kaya.1993. Insect Pathology. Academic Press, San Diego. Chapter 6. pages171-218.

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