Polyhedral Virus Research Articles

Philosophy on the Biological Control of Insect Pests

AbstractBiological control may be defined as the balance between a species and biological stress factors that limit its potential population. Four major divisions are usually recognized in biological control research programs: (i) parasites and predators; (ii) insect pathology; (iii) radiation and genetics; (iv) host‐plant resistance.Introducing parasites and predators to combat introduced insect pests was vigorously pursued during the early 20th century. Again in recent years this facet of biological control research has received increased emphasis. Successful establishment of many introduced parasitic species has been recorded. Components of biological control agents usually lag in effect when host populations suddenly increase. Each species has its own realm of environmental requirements for optimum survival.Pathogenic viruses, bacteria, fungi, protozoa, and nematodes may reduce insect outbreaks rapidly under favorable temperature and moisture conditions. Examples include: (i) polyhedral viruses present in many species of Lepidoptera; (ii) milky disease bacteria in the Japanese beetle, and Bacillus thuringiensis in the European corn borer; (iii) fungi of the genera Empusa or Entomophthora, Beauveria, and Metarrhizium in many orders and a wide range of species; (iv) protozoa of the genera Nosema and Perezia in a wide range of hosts. Artificial dissemination has been successful for milky disease against the Japanese beetle and B. thuringiensis against the European corn borer. Male sterility induced genetically or by radiation is a promising approach to insect population control.Cooperative research programs have yielded significant varietal resistance to several insect species in economically important field crops such as wheat, maize, sorghum, and alfalfa.

Viruses of Entamoeba histolytica. I. Identification of transmissible virus-like agents.

This and a companion report deal with the identification and morphogenesis of viruses in axenized cultures of Entamoeba histolytica. There are probably two different types of virus each producing a different pathological picture in different amoebal strains, or, less likely, there is one type of agent having widely different morphological and morphogenetical pictures in different strains of E. histolytica. Both types of agent produce a lytic response in axenized amoebae and have been serially passaged to an extent assuring their replicating nature. One appears to replicate in the nucleus as multiple clusters of fine filaments which ultimately lyse the nucleus, causing cell death. The second type of agent appears to be a typical polyhedral virus, seen only in the cytoplasm and also resulting in lysis of the cell. A particle morphologically indistinguishable from this second agent is also found in late passages of the agent producing the nuclear pathology.

Antiviral activity of double stranded RNA from a virus isolated from Aspergillus foetidus.

IN recent years virus particles with the property of inducing interferon production in animals have been isolated from Penicillium stoloniferum1,2, P. funiculosum2 and P. cyaneofulvum3. Virus particles have also been isolated from penicillin producing strains of P. chrysogenum4 and we have shown that both the particles and derived double stranded RNA are active interferon inducers in animals (unpublished results). Following the observation5 that a high level of cell wall galactosamine seemed to be associated with the presence of virus particles in P. stoloniferum, we have examined a number of fungi, reported to contain cell wall galactosamine, for possible virus content. One of those examined, Aspergillus niger (strain IMI 146891)ast;, was found to contain polyhedral virus particles; similar particles were also found in a closely related species, A. foetidus (strain IMI 41871). This is the first report of virus particles in the genus Aspergillus. We now describe the isolation and purification of the A. foetidus virus and provide evidence that the RNA isolated from the virus particles is double stranded. We have found that both virus particles and double stranded RNA are active in inducing interferon production and protecting mice against encephalomyocarditis and Semliki Forest viruses.

Three Types of Virus Particle in Penicillium stoloniferum

IT has been demonstrated recently that virus particles and double stranded viral RNA isolated from Penicillium stoloniferum (ATCC 14586) are potent inducers of interferon in animals1–3. We now report that this strain of P. stoloniferum contains three polyhedral viruses: two serologically distinct particles of similar size (25–30 nm diameter) and small numbers of a third larger particle (40–45 nm diameter).

EFFECTS OF THREE HORMONAL MIMICS ON MORTALITY, METAMORPHOSIS, AND REPRODUCTION OF THE WESTERN TENT CATERPILLAR, MALACOSOMA CALIFORNICUM PLUVIALE

AbstractThe western tent caterpillar, Malacosoma californicum pluviale (Dyar) was treated externally with farnesyl methyl ether and the crude ether extracts of two forest trees, Western Red Cedar (Thuja plicata) and Douglas-Fir (Pseudotsuga menziesii). Within 24 hr of the intervening molts, late fourth- and early fifth-instar larvae weighing 178 mg received 55 μg, and late fifth-instar larvae and new pupae weighing 450 mg received 140 μg in 0.6 μl of acetone. Controls received only acetone.Treated groups suffered increased mortality due to structural abnormalities, molting difficulties, and increased infection with polyhedral virus and microsporidia. Many surviving adults also were structurally abnormal, and the proportion of females depositing normal egg masses was reduced. The progeny were less viable than those of the controls. Reductions in the viability of progeny were only slightly affected by time of treatment, but egg-laying behavior was more affected by later than by earlier treatments.All materials produced examples of juvenility, but many of the abnormal individuals produced by cedar treatment died early in the pupal stage, whereas those induced by the other treatments lived longer. In most instances, samples were too small to indicate statistical superiority of any one material but, as received, the cedar extract seemed more potent than the fir. Farnesyl methyl ether had the greatest influence on reproductive capacity.

Parasitization of Cabbage and Alfalfa Loopers in Southern California13

Fifteen species of parasites (7 Diptera and 8 Hymenoptera) and a nuclear polyhedral virus were reared from larvae of the cabbage looper, Trichoplusia ni (Hubner); the alfalfa looper, Autographa californica (Speyer); and the bean leaf skeletonizer, Autoplusia egena (Guenee), collected on annual weeds (Malva sp., Chenopodium sp., and mustards), alfalfa, and tree tobacco, Nicotiana glauca Graham, in southern California. T. ni was the most abundant host, though A. California usually predominated in spring collections from weeds and alfalfa. Comparatively few A. egena were collected-usually on weeds. The virus and most of the parasites attacked both T. ni and A. california , but A. egena was parasitized mainly by several Hymenoptera. The tachinid Voria ruralis (Fallen) and the polyembryonic encyrtid Copidosoma Truncatellum (Dalman), were the major parasites reared. All 3 hosts were parasite zed to about the same extent (30–40%), but total mortality ranged from 53% on tree tobacco, 73% on weeds, to 94.5% on alfalfa, mainly caused by differences in virus mortality. In greenhouse cage studies to investigate their potential for mass-release experiments against the cabbage looper, V. Muralist was more effective than C. truncatellum at comparable host-parasite densities. Periodic releases of C. truncatellum in an unsprayed cabbage plot were ineffective.

Heat Effects on the Infectivity of the Nuclear Polyhedrosis Virus of Heliothis Spp.12

Studies were undertaken to define the heat susceptibility of the nuclear polyhedral virus of Heliothis spp. The results indicate polyhedra retain normal infectivity compared with the unheated control virus following exposure for 20 minutes to temperatures from ambient to 65°C. However, temperatures between 70°C and 80°C are increasingly attenuating with complete inactivation occurring at 85°C. Closely monitored time-temperature relationships show complete inactivation of polyhedra within 5 minutes of exposure at 85°C with a loss of approximately 80% of the infectivity occurring within the first 20 seconds. Correction curves are presented to assist in evaluating experimental conditions to determine the actual heating and cooling periods of the virus samples. The data presented predict that temperature alone should not be a prime inactivating agent for the polyhedra under field conditions.

Penicillium cyaneo-fulvum virus and interferon stimulation.

A polyhedral virus has been found in a strain of Penicillium cyaneo-fulvum. Double-stranded RNA isolated from the virus was active in stimulating interferon production.

A Field Test Comparing Resistant Varieties Plus Applications of Polyhedral Virus with Insecticides for Control of Heliothis spp. and Other Pests of Cotton, 1967123

Integrated control against Heliothis spp. and other cotton pests was attempted in a large-scale field test in 1967 near Santa Rosa, Texas. The results obtained when resistant strains of cotton were planted and nuclear polyhedral virus (Viron/H® and Biotrol VTN®) was applied for control of the boll worm, Heliothis zea (Boddie), and the tobacco bud worm, H. virescens (F.), compared favorably with those obtained in adjacent fields treated with methyl parathion or with methyl parathion in combination with ethyl parathion.

Direct Negative Staining Method for Detection of Virus Particles in Fresh Preparations from Infected Plant Tissues

A rapid method designated “direct negative staining method”, has been developed to detect plant virus particles in fresh preparations. It is a combination of dipping and negative staining methods, being in principle similar to that reported recently by Hitchborn and Hills (1965) and Kitajima (1965). The procedure is as follows: A drop of 2% solution of sodium phosphotungstate (adjusted to pH 7.0 with NaOH, and added with small amount of neutral detergent as a spreader) was placed on a carbon-coated grid. The drop of stain, in which a fresh cut-end of an infected tissue piece was dipped for 2-3 seconds, was air-dried. The preparation was immediately examined under the electron microscope. By this method, elongated particles could be easily detected in all the tested 13 viruses, viz., tobacco mosaic virus, sugarcane mosaic virus, potato viruses X, Y and S, cowpea aphid-borne mosaic virus and azuki-bean mosaic virus (both belong to bean yellow mosaic virus group), carnation mosaic virus (=carnation vein mottle virus), soybean mosaic virus, soil-borne wheat mosaic virus, and barley yellow mosaic virus.As regards spherical or polyhedral viruses, particles of a virus isolated from Chenopodium album, carnation mottle virus, rice dwarf virus, rice black-streaked dwarf virus and tobacco ringspot virus were identified readily. Difficulty in revealing spherical or bacilliform particles in cucumber mosaic virus and alfalfa mosaic virus was considered to be due to breakdown of the particles during the treatment. In these viruses, however, a number of particles became discernible when the tissue piece to be examined was fixed by 5-10% formalin for 2-3 hours, and washed in distilled water, in advance of dipping. It was noted that the shape and fine structure of the particles in the preparations of all the foregoing viruses were well-preserved and the dimensions measured were comparable with those of previous workers. The direct negative staining method described here seems to be useful for detection of plant viruses. Especially it has advantage of simplicity and reliability in detection of latent viruses or virus complex. For instance, a preparation made from a carnation plant (cultivar Peter Fisher) infected with both carnation mosaic virus and carnation mottle virus readily demonstrated elongated particles of the former virus and spherical particles of the latter.

Antifeeding Effect of DDT on Bollworm and Tobacco Budworm larvae123

In studies of the nuclear polyhedral virus residue, we observed that the larvae of Hellothis spp. did little feeding on leaf disks made from cotton leaves (cultivar Stoneville 7A) that had been sprayed with a mixture of toxaphene and DDT. Our observations suggested that this mixture deterred larval feeding. A mixture of toxaphene and DDT has been evaluated as a toxicant against larvae of the bollworm, Heliothis zea (Boddie), and the tobacco budworm, H. virescens (F.), in the laboratory (Adkisson 1967, Adkisson and Nemec 1967) and in the field (McGarr and Chapman 1963, McGarr 1968). Young and Hamm (1966) tested the polyhedral virus separately and in combination with DDT as a control for bollworms (corn earworms) on sweet corn. They found the control of bollworm larvae did not usually increase appreciably when 100 larval equivalents of virus were used in combination with DDT at 2 lb/acre compared with the control achieved when DDT was used alone. However, in 1 test, the virus with DDT did give a significant difference in yield over virus alone. We therefore tested toxaphene and DDT separately and in combination in the laboratory to corroborate the apparent antifeeding effect observed in the field.

A serological study of polyhedral cytoplasmic viruses isolated from amphibia

Antisera to FV3, a frog virus of the cytoplasmic polyhedral type, were prepared in rabbits and tested for virus-neutralization and precipitating activity with FV3 and eight other isolates of amphibian viruses of the same morphological type (FV1, FV13, FV16; LT1, LT2, LT3, L4b, and TEV). After appropriate absorption, two strong precipitation bands were formed in Ouchterlony tests with viral antigens prepared from ether-treated extracts of FV3-infected cultures; both bands gave reactions of identity with all nine virus isolates. Rabbit anti FV3 serum had similar neutralizing activity against the four FV viruses and LT1 and TEV virus isolates. Thus the nine isolates were not distinguishable either by virus-neutralization or by immunodiffusion tests with these antisera. In addition, FV1, FV3, LT1 and TEV produced a lethal infection in young Fowler's toads, the gross pathology being similar in each case. The results suggest that these isolates of polyhedral viruses are closely related or represent a single agent which has been obtained from various species in different geographical locations.

Electron Microscopic Observations On An Amphibian Polyhedral Virus (LT-1) Propagated in Vitro in Reptilian Cells

Polyhedral, cytoplasmically derived, viral agents have been isolated from Rana pipiens and characterized in baby hamster kidney and Fathead minnow cells in vitro. These viruses are not similar to the Herpes-type virus associated with the Lucké tumor in these frogs. Clark, et al have recently described additional isolates of similar polyhedral agents from the leopard frog after passage through red efts (Triturus viridescens). This virus series, designated LT-1, -2, -3, -4, has been propagated in the turtle heart cell line TH-1. This report presents morphological studies on these isolates.Slow speed centrifuged cell packs were fixed in cold chrome-osmium (Dalton) followed by fixation in cold 0.5% aqueous uranyl-acetate with 0.54% sucrose. Sections were double stained with uranyl-acetate and lead citrate.The virus particles were observed to form in juxta-nuclear viroplasmic regions within the cell cytoplasm. Evidence of intranuclear virus synthesis has not been observed, to date. Viroplasmic regions were frequently surrounded by mitochondria. Within the viroplasmic regions the fixation used preserved a filamentous mesh work which is observed to be continuous with that which is accumulated inside the virions (Figs. 1, 2). This filamentous material is similar to that observed in Mycoplasma and in poxvirus viroplasm.

Laboratory and field experiments on the effectiveness of purified and non-purified nuclear polyhedral virus ofLymantria dispar L.

Des experiences de laboratoire et en plein champ ont revele que le virus de la polyedrose nucleaire deLymantria dispar L. est plus efficace quand on l'emploie sous forme de suspension non purifiee.

Field Tests with a Nuclear Polyhedral Virus Against the Bollworm and Tobacco Budworm, 1964-196612

Field Tests with a Nuclear Polyhedral Virus Against the Bollworm and Tobacco Budworm, 1964-196612

Electron microscopy of leaves infected with sowbane mosaic virus and other small polyhedral viruses

Leaves of Chenopodium amaranticolor were infected with sowbane mosaic virus (SMV), sectioned and examined by electron microscopy. Leaves of Brassica pekinensis and C. amaranticolor were infected with turnip yellow mosaic virus and cowpea mosaic virus, respectively, and similarly studied. With all three viruses it was difficult, in sections, to distinguish the small isometric virus particles from ribosomes though sometimes this was possible, especially when the viruses crystallized. Pretreatment of tissue with permanganate or EDTA appeared to destroy the ribosomes but resulted in excessive disorganization of the tissue. Although SMV did not normally crystallize, wilting the infected leaves caused it to do so. All three viruses were found free in the cytoplasm and were absent from nuclei, chloroplasts, and mitochondria. Some abnormal structures found in the infected tissues are described.

Generation-to-generation passage of the nuclear polyhedral virus of Spodoptera exempta (Wlk.).

GENERATION-TO-GENERATION passage of polyhedral viruses has been reported for a number of insects1–5. Previous work with the nuclear polyhedral virus of Spodoptera exempta (Wlk.) indicated that generation-to-generation passage of the virus occurred in this insect, but the evidence was inadequate to decide whether the virus passed within the egg or by contamination of the egg shell6. This communication presents the results of experiments on this question.

Passage des corps d'inclusion de virus d'une polyédrie nucléaire dans le tube digestif d'un orthoptère détritivore,Acheta domesticus L.

Passage of nuclear polyhedral virus inclusion bodies in the gut of the detritiphagous OrthopteronA. domesticus is described. Histological studies permitted following the rate of passage and the elimination time of the inclusion bodies.

Dissémination des virus de polyédries par les Éphippigères prédateurs d'insectes

Transmission of polyhedral viruses byEphippiger bitterensis having ingested virus diseasedLymantria dispar larvae was observed in nature and in experiments. The passage of polyhedral bodies in different parts of the gut was studied by histological methods and the effect of the gut juice was found insignificant. These bodies were detected in dejections during 15 days after ingestion of diseased insects. Viruses were shown by electron microscope and the conservation of their pathogenic effect by infection tests. Significantion of these results in epizootiology and in biological control is discussed.

Arabis mosaic and Prunus necrotic ringspot viruses in hop (Humulus lupulus L.)

SUMMARYPurified virus preparations made from nettlehead‐diseased hop plants, or from Chenopodium quinoa, to which the virus was transmitted by inoculation of sap, contained polyhedral virus particles of 30 mμ diameter which were identified serologically as arabis mosaic virus (AMV). There were serological differences between AMV isolates from hop and from strawberry, and also differences in host range and in symptoms caused in C. quinoa and C. amaranticolor. AMV was always associated with nettlehead disease. The nematode Xiphinema diversicaudatum occurred in small numbers in most hop gardens, but was numerous where nettlehead disease was spreading rapidly.Preparations from nettlehead‐affected hops also contained a second virus, serologically related to Prunus necrotic ringspot virus (NRSV), in mild and virulent forms which infected the same range of test plants but showed some serological differences. Mild isolates did not protect C. quinoa plants against infection by virulent isolates. Hop seedlings inoculated with virulent isolates of NRSV developed symptoms indistinguishable from those of split leaf blotch disease. Latent infection with NRSV was prevalent in symptomless hop plants. Nettlehead disease is apparently associated with dual infection of AMV and virulent isolates of NRSV.An unnamed virus with rod‐shaped particles 650 mμ long was common in hop and was transmitted by inoculation of sap to herbaceous plants. Cucumber mosaic virus was obtained from a single plant of Humulus scandens Merr.