Viruses biological 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. 

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... 

In the remaining pages I shall discuss in greater detail the NPVs and their applications in biological control of insect pests. These viruses have been studied intensively during the... 

One approach in biological control is to make the pathogens sick. Bacteriophages, which are viruses that infect bacteria, have been used experimentally to infecrand weaken the bacteria that cause bacterial wilt of tomatoes and fire blight on pears. 

What can be done with virus infections is exemplified by the strong killing action of the myxomatosis virus in rabbits following its careful liberation in Australia (1950) and France (1952). However, the use of viruses for biological control is out of favour because of the risk of adding malign genes to the chromosomes of economic species, Man included. 

Biological control of rabbits, using Myxoma virus, has been successful in Australia, where it was first undertaken. Although a moderate degree of resistance has now set in, the survivors are easily exterminated with sodium fluoro-acetate (non-selective). 

NPVs have few deleterious effects on other biological control agents. NPVs do not directly affect predators and adult parasitoids as chemical insecticides often do, and NPVs do not infect parasitoid larvae in virus-infected hosts. However, the early mortality of host larvae, due to virus, may result in death of parasitoid larvae if the parasitoids do not have time to complete development. 

Since the early 1900s, biological control of the rat and field mouse has been attempted, on a large scale, from one end of Europe to another. Usually a species of Salmonella bacteria (sometimes misbranded rat virus ) was used, and false claims were made that the organism was specific for the rat. Actually these bacteria are pathogenic to Man and several epidemics have been started in this way (Wodzicki, 1973). A joint WHO/FAO expert committee strongly condemned this form of biological control in 1967. 

---