Pest Control and Biopesticides, Bacterial Pesticides, Viral Pesticides, Biological Insecticides, Bacillus Thuringiensis

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Pest Control and Biopesticides
Bacterial Pesticides are also being developed (even though they are slow in action and are expensive) and a company in U.S.A with the name Ecogen Inc. established in 1983, made Some progress in this direction. Heliothis complex, which lives in close association with plant roots consists of two major crops pests, namely budworm and bollworm.

Some viral pesticides, with the names of pests they control

Class of virus	Pest	Trade name	Crops
1. Nuclear polychedrosis viruses (NPVs) (subgroup a of Baculoviridae)
(a) Baculovirus heliothis	Heliothis	Elcartm, Biotrol VHZ. Viron/H	Cotton & other crops
(b) Gypsy moth baculovirus	Lymantria dispar	Gypcheck	Hardwood trees
(c) Sawfly baculovirus	European sawfly (Neodiprion sertiferis), N. lecontel and other sawflies	Polyvirocide	Forest or tree plantations
(d) Brassica NPV	Trichoplysia ni	Biotrol-VTN	Brassica
(e) Cotton NPV	Spodopter litura	Biotrol-VSE	Cotton
2. Granulosis Viruses (GVS) (subgroup B of Baculoviridae)	Cydia pomonella	-	Apple, vegetables
3. Cytoplasmic polychedrosis viruses (CPVs)	Thaumetopoea pityocampa, Dendrolimus spectabilis and othersa	-	Pine, spruce, etc

Biological insecticides against both these insects are being prepared by transfer of a gene from Bacillus thuringiensis (Bt) into either a naturally occurring soil bacterium, or into a strain of Pseudomonas. Bt insecticides are already in the market for 30 years and in future these will be modified through techniques of genetic engineering and will be utilized against a variety of insects.

Several companies in USA including Ecogen, Monsanto, Mycogen, Repligen and Zoecon are involved in development and marketing of biological pesticides. Among these, while Monsanto was using genetically engineered live soil bacteria, for coating seeds before planting, Mycogen kills recombinant bacteria and applies them to the leaves of crop plants.

Both these approaches protect the toxin from degradation by microorganism or ultraviolet light, once applied to crop plants. Genetically engineered insect resistant plants have also been successfully produced in some crops thus raising the hope for reduced use of insecticides in future.

Viral pesticides have also been successfully developed and used for the control of pests. These pesticides are environmentally safe and can also be used against the pest strains which have becomes resistance to chemical pesticides. A number of entomopathogenic viruses (viruses which can cause infection to insects) belonging to the family Baculoviridae (baculoviruses or nuclear polychedrosis viruses = NPV) and family Reoviridae (cytoplasmic poyhederosis viruses or CPVs) have been used as safe and effective pesticides.

These viruses infect and kill host (pest) by gaining entry through mouth into the digestive tract. They have no adverse effects on useful insect pollinators, insects yielding useful products, parasites or predators, warm blooded mammals or even man. They are safe even in large scale spray operations. However, large scale production of these viruses demands either living host or its cells for multiplication. Some of these entomopathogenic viruses.