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ForestAwareness

technical reference

insecticide

NUCLEAR POLYHEDROSISVIRUSES

• BASIC FACTS

1. Common Name:

NPVs (Nuclear Polyhedrosis Viruses)

2. Biological Classification:

Baculovirus; family Baculoviridae.subgroup A.

3. Active Ingredient:

The particles which initiate infection in the insectare called virions. These rod-shaped structuresare embedded in proteinaceous crystal bodiescalled polyhedra, or more commonly, polyhedralinclusion bodies, (PIBs). The number of virionsfound in PIBs vary greatly among viruses.Preparations of NPVs can be standardized, in part,by determining the number of PIBs per unitmeasure of the mixture.

Magnification 45920X

4. Forestry Commercial Products:Name Manufacturer Reg. Target Guarantee

No.

Under

PCPA"

Lecontvirus F.P.M.I." 17824 Red-headed 5 x 103pinesawfly PIBs/ml

Virtuss F.P.M.I. 17786 Douglas-fir 20x109tussock PIBs/ml

moth

TM BioControl-1c U.S.Forest

Service19293 Douglas-fir 70x106

tussock A.u./gamoth

0 Forest Pest Management Institute.b Pest Control Products Actc TM BioControl-1 is an NPV registered in Canada for the control of the

Douglas-fir tussock moth. This product is produced in the United States andis identical to the Canadian product called Virtuss.

l!The weight of TM BioControl-1 powder to treat each hectare is determinedby bioassay and varies with each lot. Activity units, (A.u.), are an expressionof the LDr,o dosage, and are usually expressed as potency; the numberof A.u 'g of virus preparation. (Marignoni and Iwai, 1978).

5. Physical and Chemical Properties:

Production: NPVs are produced in living insectlarvae. Healthy larvae are infected with NPV andharvested after the virus infection has had time to

spread throughout the larvae. This usually takesfrom 10 to 12 days. Polyhedra can be purifiedfrom these larvae, or more often, the whole of theinfected larva is freeze dried and ground to afine powder. This powder contains NPVs.Appearance: Purified polyhedra are white whenin aqueous suspension. Ground larvae are a greypowder.Odour: Slight and characteristic.Stability: Purified polyhedra and powders can bekept for several years with little loss of activity.It is not recommended to keep NPVs in theformulated state for more than 2 months.Solubility: Soluble in water and oil formulationswith pH between 6 and 8.

6. History:

Insect viruses were discovered in the 19th century,and have been known to cause high mortalityin insect populations. In Canada, an NPV was firstused to control a forest pest in 1950, when outbreaks of the European spruce sawfly, Gi/pineahercinae (Hartig), became severe (Bird andBurke, 1961). Many insect species are known to besusceptible to NPVs, but because of the complexnature of virus-insect relationships, only a fewNPVs have been found suitable to be developedas biological insecticides.

7. Insecticide Spectrum and Mode of Action:

NPVs are very host specific and replicate in onlyone, or in a few related host species (Vaughn etal., 1977). Polyhedra must be eaten by the insectlarvae to be effective and cause death. Once

polyhedra are injested, they are dissolved by thealkaline pH of the insect gut. This releasesvirions into the stomach which penetrate the cellsof the gut and initiate cellular infection. Polyhedraare produced in these infected cells, and within10 to 12 days the larva dies of NPV infection. As thelarva disintegrates, these newly formed polyhedraare released into the forest and are available to

infect other insects of the same species.

REGISTERED USESAND APPLICATION TECHNOLOGY

1. Registered Uses for Forestry:

The NPVs registered in Canada are for restricteduse and can only be applied under the directsupervision of Federal or Provincial ForestryService personnel. These products are registeredfor Forest management use (>500 ha), and Woodlands management (<500 ha). May be appliedby ground or aerial spraying.

2. Operational Details:

Potential users are referred to the official label,local/provincial laws and regulations, federal andprovincial regulatory officials for details necessary to plan specific projects. The timing of theapplication will depend on the stage of development of the target insect.

• Timing and Dosage:Product Timing Dosage

Lecontvirus 1st and 2ndinstars

5x109PIBs/ha

Lecontvirus 3rd and 4thinstars

10 x 109PIBs/ha

Virtuss 1st and 2ndinstars

2.5x10" PIBs/ha

TM BioControl-1 1st and 2nd

instars2.68x109A.u./ha

Mixing:a) LecontvirusLecontvirus is usually supplied as a suspension inemulsifiable oil which is diluted in water, as outlined below, for either aerial or ground application.

Rates for aerial applicationLarval Rate of lecontvirusinstar per hectare

Water* Total

emitted

volume

per

hectare

Milli-

litres PIB Litres Litres

Plantations 1st & 2nd 10 5x109(5 billionpolyhedral inclusion bodies)

9.4 9.4

3rd & 4th 20 10x109(10 billionpolyhedral inclusion bodies)

9.4 9.4

Rates for ground applicationLarval Rate of lecontvirusinstar per hectare

Water* Total

emitted

volumeper

hectare

Milli-

litres PIB Litres Litres

Plantations 1st & 2nd 10 5x109(5 billionpolyhedral inclusion bodies)

20 20

3rd & 4th 20 10x109(10 billionpolyhedral inclusion bodies)

20 20

b) Virtuss.Virtuss is a freeze dried powder and suspensionsare possible in both aqueous and emulsifiableoil. However, for aerial applications, the emulsifiable oil is recommended.

Rates for aerial applicationRate of virtuss

per hectareGelled oil

vehicle

Water* Total

emitted

Volume

per

hectare

Grams PIB Litres

Forest 12.5 2.5x10"(250 billionpolyhedral inclusion bodies]

25% totalvolume

75%

total

volume

9.4

Virtuss may also be applied by ground equipmentto woodlands, along right-of-ways, in treenurseries or seed orchards and in treed areasof less than half a hectare where high valued orornamental trees may be attacked.

Rates for ground application

Treed areasunder0.5 ha

Rate of virtussper hectare

Water*

Grams PIB Litres

12.5 2.5x10"(250 billionpolyhedralinclusion bodies!

1000

Total

emitted

Volume

per

hectare

Litres

1000

total

•Chlorinated or highly alkaline water should not be used in tank mixes. Tankmix pH should be between 6.0 and 7.2. pH can be adjusted by adding NaOH(sodium hydroxide) if it is below 6.0.

c) TM BioControl-1.TM Bio-Control-1 is a freeze dried powder andsuspensions in water or emulsifiable oil can beapplied in aerial application.

Rates for aerial application emulsifiable oilRate of TM Biocon- Abbott Water* Total

trol-1 per hectare labora emitted

tories volume

gelled oil per

vehicle hectare

Grams Activity Units Litres

Forest 3.5-7.0 2 681 x 109 25% total 75%volume total

volume

9,1

In water

Forest

Rate of TM Biocon-

trol-1 per hectare

Grams Activity Units

3.5-7.0 2 681 x 10s

Molasses Water*

25% total 75%volume total

volume

Total

emitted

volume

per

hectare

Litres

9.4

TM BioControl may be applied by ground equipment to woodlands, along right-of-ways, in treenurseries or seed orchards and in treed areas

of less than half a hectare where high valued orornamental trees may be attacked.

Rates for ground applicationRate of TM BioCon-

trol-1 per hectareWater- Total

emitted

Volume

per

hectare

Grams A.u. Litres Litres

Treed areas 3.5-7.0 2.681 x 109under 0.5 ha (2.681 billion A.u

1000

)1000

Note: You can add 1% colorant for checking methods.

• EFFECTS ON BIOTA

1. Insects Controlled:

NPVs are extremely host specific. Lecontvirus isonly effective against the red-headed pine saw-fly, Neodiprion lecontei (Fitch). Virtuss and TMBioControl-1 are registered for use against theDouglas-fir tussock moth, Orgyia pseudotsugata(McDunnough).

2. Effects on Non-Targets:

NPVs are naturally-occurring pathogens found inmost insect populations. They present no hazardto the environment and non-target organisms.Extensive safety testing involving several speciesof birds, mammals and non-target invertebrateshave been conducted and these results are

included in the documentation for registrationof each NPV. Copies of these reports can beobtained on request from FPMI. Doller (1985)provides an excellent review on the safety ofinsect viruses.

• SAFETY

1. Handling:

Care must be exercised when handling an insecticide, although NPVs are environmentally safe,some additives to the spray formulation may beharmful at concentrated levels.

• Wear rubber boots, rubber suit or apron, rubbergloves, respirator, goggles and cap or hat whenmixing/processing concentrates.

• Contaminated clothing should be removed andwashed before use.

• If spilled on skin wash immediately with soapand water.

• Wash hands before smoking or eating.• Keep unauthorized and unprotected persons out

of loading or mixing zones.

2. Product Precautions:

Avoid contact with skin, eyes or clothing.Avoid inhalation.

Do not contaminate food or any body of water.

3. Disposal and Storage:

Do not store at temperatures above 32° C.Do not reuse empty container.Destroy or discard empty container in a safeplace, according to government disposalregulations.

4. Medical Treatment:

• Skin and eye irritant.In case of contact, immediately flush eyes or skinwith plenty of fresh water. Get medical attentionif irritation persists, or if swallowed in any largeamount.

• QUESTIONS AND ANSWERS

Q. Is it safe to use nuclear polyhedrosis viruses?A. NPVs are naturally-occurring pathogens foundin most insect populations. As such they arealready present in the environment and persist toregulate insect populations. Often the quantityof NPVs present is too low to cause any noticeablereduction in the insect population. Introductionof NPVs into these populations serves only toaugment the quantities of NPVs naturally present,at levels which will cause widespread diseaseand insect mortality. No other animal is affectedby this technique.

Q. Can NPVs infect vertebrates?

A. NPVs are a very special type of virus whichinfects only certain insect species. No measurable virus replication has been detected in non-target organisms like birds, fish and mammals(Doller, 1985). However, biologically active viruscan be found in the faeces of some animals, for

example, birds, which indicates that they areable to spread the NPV throughout the forest(Entwistleetal., 1977).

Q. How long do NPVs remain in the forest?A. NPVs can persist up to 40 years in the forestsoil (Thompson et al., 1981). Research has indicated that infectious polyhedra are detected onfoliage for up to 3 years after insect larvae havebeen killed by this disease. Although NPV is shortlived on foliage, it can persist on bark for longperiods and be transferred to foliage by rainfall(Kaupp, 1983).

Q. Are there any drawbacks to using NPVs?A. Yes, there are some minor drawbacks to theuse of NPVs in forest insect control. Because the

NPV takes up to 2 weeks to kill the larvae, somedefoliation must be expected. Also, under highpopulation levels, the NPV is not as efficient acontrol as are some chemicals because of the

mode of action, delay in insect death and limitednumbers of polyhedra available to cause infection.

Q. Are there any other biological insecticideslike Lecontvirus, Virtuss and TM BioControl-1available?

A. An NPV product called Sertifervirus, iscurrently undergoing review for registration inCanada. This NPV controls the European pinesawfly, Neodiprion sertifer (Geoffrey). Presently,F.P.M.I. is developing an NPV which infects thegypsy moth, Lymantria dispar (L.)and it is hopedthat this product will be registered for forestryuse in the near future.

Q. Have NPVs been used operationally inthe past?A. In the United States, TM BioControl-1 hasbeen used operationally since 1976 to control outbreaks of Douglas-fir tussock moth, 0. pseudos-ugata. Another product called Gypchek, the NPVinfecting the gypsy moth, L. dispar, has been inuse operationally since 1979.In Canada, Virtuss and TM BioControl-1 havenever been used operationally, however extensiveresearch has indicated that both these preparations are very efficacious. Presently, Virtuss andTM BioControl-1 are being stockpiled in anticipation of the next outbreak of Douglas-fir tussockmoth, 0. pseudotsugata. Lecontvirus, the NPVinfecting the red-headed pine sawfly, N. lecontei,is in operational use by Provincial authorities.

• REFERENCES

1. Addresses of Manufacturers:

Forest Pest Management Institute,Canadian Forestry Service,P.O. Box 490,SaultSte. Marie,Ontario,Canada P6A5M7

U.S. Forest Service, USDA,14th and Independence Avenues,Washington, D.C.USA 27 709

2. References in the Text:

Bird, F.T. and J.M. Burke, 1961. Artifically disseminated virus as a factor controlling the Europeanspruce sawfly, Diprion hercyniae (Htg.) in centralNew Brunswick. Can. entomol. 93:228-238.

Doller, G., 1985. The safety of insect viruses asbiological control agents, in Viral insecticidesfor biological control. (K. Maramorosch andK. Sherman, eds.) Academic Press, New York.

Entwistle, PR, P.H.W. Adams and H.F. Evans, 1977.Epizootiology of a nuclear polyhedrosis virusin European pine sawfly, Gilpinia hercyniae:The status of birds as dispersal agents of the virusduring the larval season. J. Invertebr. Pathol.29:354-360.

Kaupp. W.J.,1983. The persistence of Neodiprionsertifer (HymenopteraDiprionidae) nuclearpolyhedrosis on Pinus contorta foliage. Can.Entomol. 115,869-873.

Martignoni, M.E. and P.J. Iwai, 1978. Activitystandardization of technical preparations ofDouglas-fir tussock mothBacu\ov\rus. J. Econ.Entomol. 71:473-476.

Thompson, C.G., D.W. Scott and B.E. Wickman,1981. Long-term persistence of the nuclearpolyhedrosis virus of the Douglas-fir tussockmoth, Orgyia pseudotsugata (Lepidoptera:Lymantriidae), in forest soil. Environ. Entomol.10:254-255.

Vaughn, J.L., R.H. Goodwin, G.J. Tompkins andP.M. McCawley,1977. The establishment of twocell lines from the insect Spodoptera frugiperda(LepidopteraiNoctuidae). In Vitro 13: 213-217.

3. Other References:

Cunningham, J.C. 1982. Field trials withbaculoviruses in Microbial and viral pesticides.(E. Kurstak ed.) Marcel Dekker, New York.

While the information in this Technical Referencehas been compiled from source materialsavailable at the time of publication, the authorsdisclaim all liability with respect thereto.

Additional copies are available in English and inFrench from the

Canadian Pulp and Paper AssociationForest Protection Committee

Sun Life Building, 23rd Floor1155 Metcalfe Street

Montreal, QuebecCanada H3B 2X9

Tel. (514) 866-6621or from

The Forest Pest Management InstituteCanadian Forestry ServiceP.O. Box 490

Sault Ste. Marie, OntarioCanada P6A 5M7

Tel. (705) 949-9461 s/f