Viruses pest control

Pestox III has been effectively used by Pest Control Ltd. to arrest transmission of the strawberry viruses by virtue of the 100 per cent kill of the strawberry aphis. 

The chemical found to be the most effective to date for the control of the mealy bugs is dimefox (bisdimethylaminofluorophosphine oxide). This is the active ingredient of the commercial product Hanane produced by Pest Control, Ltd., London, which holds a contract for investigation and control of swollen shoot viruses. Hanane is applied to the soil around the roots of the trees and a very significant reduction in the mealy bug population has been obtained by this method. 

The pest control situation in California and Florida is reviewed, with particular attention to mechanical developments and the introduction of new fungicides and insecticides, such as the insoluble coppers and parathion, and the outstanding unsolved problems such as control for nematodes which will not injure the plant and the need for a systemic material which will control virus diseases. Emphasis is on needed lines of investigation. Pest control problems in Central America, the Caribbean Islands, and South America are discussed, with special reference to lack of suitable equipment and material because of dollar exchange problems. 

Some groups of entomopathogenic viruses are capable of causing severe epizootic diseases in insect populations. We consider these viruses excellent natural pest control agents if the host insects are destructive species. Natural epizootics of viral diseases are known to have terminated outbreaks of major forest pests, such as the nun moth in Europe and the Douglas-fir tussock moth in the United States. 

Baculoviruses play a central role in the natural control of insect pest populations, chiefly Lepidoptera. This has sustained an interest in the commercial potential of these as larvicides in several pest control situations however, performance drawbacks have limited their general usefulness. Modification of the viruses through genetic engineering is anticipated to greatly increase their effectiveness. How this may be accomplished will be discussed. The effect modifications may have on the well-established safety of these agents as well as their perceived safety will also be covered. 

Pesticides are chemical agents used for pest control, that is, substances used by humans to kill or control undesired organisms. The term excludes pathogenic organisms such as bacteria, viruses, and protozoa. Pesticides may be classified according to their functions. Such a classification includes some common terms, such as the following ... 

The specificity of the viruses can be either an advantage or a disadvantage. Because the viruses are host specific, they will not kill beneficial insects such as honey bees or parasitic insects. Therefore, using viruses does not remove the natural pressures on the target insect or on other potential pests controlled by parasites or predators and lead to increased need for chemical control. They will not harm plants or vertebrates nor will they accumulate in other organisms in the food chain as do some chemicals. Because of their specificity and the fact that they can multiply in the field after application, no tolerance levels are established for viruses thus, there is no residue problem. 

JHE was expressed under control of a modified viral promoter in AcNPV constructs with, and without, expression of EGT (Table I), ggr-minus viruses (without JHE) are slightly more effective in terms of speed of kill, than eg/-positive viruses (59). Analysis of weight gain of larvae infected with the test viruses, and of bioassay data for lethal time and viral dose, indicated that there was no difference in the activity of expressed JHE in the presence or absence of EGT. The reason for this is unclear. However, the bioassays reported were carried out on fourth and fifth instar larvae of T. ni Precocious development would not be detectable at this late stage, as the larvae would normally pupate very shortly after the time chosen for infection. Bioassays on early instar larvae are also preferable in terms of field applicability, as early instars will be targeted for optimal pest control. 

In yet another application of plant virus peptide presentation systems, Borovsky [52] used TMV to present a peptide, trypsin modulating oostatic factor (TMOF), that terminates trypsin biosynthesis in the mosquito gut and causes larval mortality. This unique study uses plant virus particles for the biological control of insect pests. 

Bunchy-top, a virus, is epidemic in Australia and the Pacific Islands but has not spread from that area. Control of the banana aphid vector and roguing of infected plants has so far kept this pest under control. 

Cucumber mosaic virus pictured on p.89) can, despite its name, affect all members of this family, and many other plant families, too. There Is no cure, but some cultivars show some resistance. Protect young plants from slugs. Powdery mildew may be a sign of dry soil late In the year It will not affect the crop. Under cover, biological controls can be used to control pests like red spider mite. Crop rotation, good... 

Do everything you can to prevent disease, as it can spread rapidly. Virus diseases are very difficult to control and affected plants should be removed and composted as soon as you notice them. The risk of infection by some fungal diseases can be reduced by raising the pH of the soil with lime (seep.55). Crop rotation (see pp.230-233) also plays an important role in reducing the severity of other soilborne diseases and some pests. 

What to do Control the pest spreading the virus. Grow resistant cultivars. Plant certified virus-free planting material. 

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