Histopathology of cytoplasmic polyhedrosis virus (Reoviridae) infection in corn earworm, Helicoverpa zea (Boddie), larvae (Insecta: Lepidoptera: Noctuidae)

1991 ◽  
Vol 69 (8) ◽  
pp. 2121-2127 ◽  
Author(s):  
C. F. J. Bong ◽  
P. P. Sikorowski
Keyword(s):  
Helicoverpa Zea ◽  
Heliothis Zea ◽  
Goblet Cells ◽  
Corn Earworm ◽  
Cell Organelles ◽  
Cytoplasmic Polyhedrosis Virus ◽  
Polyhedrosis Virus ◽  
Columnar Cells ◽  
Lepidoptera Noctuidae ◽  
Virogenic Stroma

Histopathology of cytoplasmic polyhedrosis virus (CPV) infection in the larval midgut of the corn earworm, Helicoverpa (=Heliothis) zea (Boddie) is described. Small polyhedral inclusion bodies (PIB) are observed in columnar cells of the midgut 1 or 2 days after treatment with CPV. Virions are partially or completely occluded in a polyhedral matrix to form PIB at the periphery of the virogenic stroma. PIB are dodecahedral in shape with a hexagonal outline and measure from less than 1 to 4 μm in size. Virions measure about 50 nm in diameter. Microvilli of infected columnar cells are not affected until immediately prior to rupture of the cell. Some infected columnar cells ruptured to release PIB into the gut lumen 2 or 3 days after infection. PIB are also released into the lumen by extrusion of heavily infected columnar cells. Mitochondria and rough endoplasmic reticulum deteriorate as infection progresses, and in many cells with advanced infection, the nucleus is obscured. PIB are found in goblet cells 5 days after infection. Infected goblet cells degenerate to such an extent that only a few of the original microvillus-like cytoplasmic projections and cell organelles are left. The implications of CPV infection in integrated pest management of the corn earworm are discussed.

Compatibility of Nuclear Polyhedrosis Viruses and Inherited Sterility for Control of Corn Earworm and Fall Armyworm (Lepidoptera: Noctuidae)

1997 ◽  
Vol 32 (2) ◽  
pp. 148-153 ◽  
Author(s):  
J. J. Hamm ◽  
J. E. Carpenter
Keyword(s):  
Helicoverpa Zea ◽  
Nuclear Polyhedrosis Virus ◽  
Fall Armyworm ◽  
Corn Earworm ◽  
Management Approach ◽  
Significant Difference ◽  
Polyhedrosis Virus ◽  
Nuclear Polyhedrosis ◽  
Lepidoptera Noctuidae ◽  
Inherited Sterility

Inherited sterility has been proposed as a means of suppressing the populations of the corn earworm, Helicoverpa zea (Boddie), and the fall armyworm, Spodoptera frugiperda (J. E. Smith). If nuclear polyhedrosis viruses could be used to kill larvae, thereby reducing the number of moths in the field populations, fewer moths treated with substerilizing doses of irradiation would need to be released. However, for these two methods to be compatible, the progeny of substerile moths should be no more susceptible to the virus than the progeny of the field populations. The corn earworm nuclear polyhedrosis virus (Elcar™) was bioassayed against corn earworm larvae from untreated moths and larvae from male, female, and male and female moths treated with 100 Gy of irradiation and larvae from male moths treated with 150 Gy of irradiation. The fall armyworm nuclear polyhedrosis virus was bioassayed against fall armyworm larvae from untreated moths and larvae from male moths treated with 100 to 150 Gy of irradiation. There was no significant difference between susceptibility of larvae from untreated moths and larvae from irradiated moths. Thus, the use of nuclear polyhedrosis viruses for control of larvae should be compatible with the release of substerilized moths as part of an integrated pest management approach for area-wide management of the corn earworm and fall armyworm.

Midgut infection of Heliothis Zea (Lepidoptera: Noctuidae) by cytoplasmic polyhedrosis virus

1989 ◽  
Vol 47 ◽  
pp. 860-861
Author(s):  
C. F. J. Bong
Keyword(s):  
Electron Microscope ◽  
Osmium Tetroxide ◽  
Heliothis Zea ◽  
Uranyl Acetate ◽  
Corn Earworm ◽  
Chronic Infections ◽  
En Bloc ◽  
Cytoplasmic Polyhedrosis Virus ◽  
Half Strength ◽  
Polyhedrosis Virus

The cytoplasmic polyhedrosis virus (CPV, Family Reoviridae) is an entomopathogen with a very wide host range, affecting mainly lepidopterous insects. The virus often causes chronic infections in insects, infecting mainly the midgut epithelium. Detailed studies of the effects of CPV on silkworm, Bombyx mori, have been done by Japanese workers , but there is very little information on the histopathology of CPV on other insects.In this study, 5-day old corn earworm (H. zea) larvae were infected per os with CPV. Control larvae were fed sterile water. The midgut was dissected out at 20, 48 and 72h post-treatment for both SEM and TEM studies. In the SEM study the midgut was fixed in 2.5% glutaraldehyde in phosphate buffer at pH 7.2, postfixed in buffered 2% osmium tetroxide at room temperature, dehydrated in ethanol, cryofractured in liquid nitrogen, critical-point dried, mounted, coated with gold-palladium and examined in a Hitachi HHS-2R scanning electron microscope at 20 kV. In the TEM study, the tissues were fixed in half-strength Karnovsky's fixative, postfixed in buffered cold 2% osmium tetroxide, en bloc stained in aqueous 0.5% uranyl acetate, dehydrated in ethanol and embedded in Spurr resin. Ultrathin sections were cut with glass knives, sequentially stained in aqueous uranyl acetate and lead citrate, and observed in a Zeiss 109 transmission electron microscope at 50 kV or a Siemens 101 at 80 kV.

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