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Microbial insecticides

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Microbial insecticides

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Microbial insecticides

  1. 1. MICROBIAL INSECTICIDES Presented by B.R.Iniyalakshimi Dept. of Soil Science and Agricultural Chemistry TNAU
  2. 2. Introduction • Microbes & microbial products used as insecticides. • Less harmfull, fewer environmental effects. • Microbial insecticides are biological preparations that are often delivered in ways similar to conventional chemical insecticides.
  3. 3. MICROBES  Bacteria  Fungi  Virus  Protozoa  Rickettsiae – not used.
  4. 4. BACTERIA  About 90 species of bacteria pathogenic to insect pests.  Bacillus thuringiensis – first discovered in 1902- japanese bacteriologists, Ishiwata from infected silk worms stands out prominent.  Bacillus thuringiensis  Bacillus popillae  Bacillus sphaericus  Coccobacillus acridorum  Serratia marcescens
  5. 5. BACILLUS THURINGIENSIS  B. thuringiensis (‘Bt’) is a spore forming gram positive crystalliferous soil bacterium.  Produces a toxin or crystal protein (Bt toxin or Cry) that kills certain insects  Commercially produced worldwide using fermentation technology.  The commercial Bt products are produced as dust, wettable powder and emulsifiable concentrates.  The toxin genes have also been genetically engineered into several crop plants.
  6. 6.  The Bt toxin or Cry is produced when the bacteria sporulates and is present in the parasporal crystal  Several different strains and subspecies of B. thuringiensis exist and produce different toxins that kill specific insects  Used as alternative to DDT and organophosphates since the 1920s  Bt toxin is used as specific insecticides under trade names such as Dipel and Thuricide
  7. 7. TARGET INSECTS FOR BT TOXIN Cry toxins have specific activities against insect species of the orders Lepidoptera (moths and butterflies), Diptera (flies and mosquitoes), Coleoptera (beetles), Hymenoptera (wasps, bees, ants and sawflies) and nematodes.
  8. 8. SOME PROPERTIES OF THE INSECTICIDAL TOXINS FROM VARIOUS STRAINS OF B. THURINGIENSIS Strain/subsp. Protein size Target Insects Cry # berliner 130-140 kDa Lepidoptera CryI kurstaki KTP, HD1 130-140 kDa Lepidoptera CryI entomocidus 6.01 130-140 kDa Lepidoptera CryI aizawai 7.29 130-140 kDa Lepidoptera CryI aizawai IC 1 135 kDa Lepidoptera, Diptera CryII kurstaki HD-1 71 kDa Lepidoptera, Diptera CryII tenebrionis (sd) 66-73 kDa Coleoptera CryIII morrisoni PG14 125-145 kDa Diptera CryIV israelensis 68 kDa Diptera CryIV
  9. 9. Figure 16.3 The toxin is inserted in gut epithelial cell membranes of the insect and forms an ion channel between the cell cytoplasm and the external environment, leading to loss of cellular ATP and insect death.
  10. 10. MODE OF ACTION  Was initially believed to kill larvae by septicaemia  It is now well established that delta-endotoxin alone is responsible for the death of most susceptible lepidopterous larvae.  After ingestion by larvae, the crystal protein broken by midgut juice proteases, under high pH > 9 conditions, into smaller toxic peptic molecules, the delta-endotoxin.  The latter causes mouth and gut paralysis within ½ hour of eating a larger doses, thus preventing further feeding within hours, the epithelium of the midgut is destroyed and gut contents invade the body cavity, rapidly causing death.
  11. 11. ORGANISM TRADE NAME TARGET PEST Bacillus popilliae - Japanese beetle B. Thuringiensis var.kurstaki Dipel, Biobit, Thuricide, Condor. Moths B. Thuringiensis var.kurstaki plus beta- exotoxin Javelin Armyworm & other moths B. Thuringiensis var. aizawi Agree Wax moth B. Thuringiensis var.tenebrionis Novodor Colorado potato beetle B. Thuringiensis var.israelensis VectoBac Mosquitoes, black flies B. Thuringiensis var.galleriae Spicturin Larvae and moths and forest insects
  12. 12. FUNGI  More than 750 species known to infect insects.  Mostly causing disease to insects.  Some attack insects through cuticle.  Spore attached to cuticle- germinates & penetrates into body wall.  Spreads – colonize the hemocoel & sometimes produce toxins.  Toxins – rapid death or death delayed until nutrients depleted or organs destroyed.
  13. 13. VERTICILLIUM LECANII  It is known as 'white – halo' fungus because of the white mycelial growth on the edges of infected scale insects.  It can be multiplied on medium based on locally available grains and tubers.  It is formulated as wettable powder.  It is effective against coffee green bug and certain other homopterans.
  14. 14. o Deuteromycotina fungus, naturally occurring in soil throughout the world. o Mass produced on locally available grains and other solid substrates. o Formulated as wettable powder, water dispersible granule, and oil based emulsifiable suspension. o Useful against Coffee berry borer, Diamond backmoth, Thrips, Grasshoppers, White flies, Aphid, Codling moth etc. o Birds: Oral LD50: (5 days) quail >2,000 mg/kg daily (by gavage). Beauveria bassiana
  15. 15. Metarrhizium anisopliae Metarrhizium anisopliae is a widely distributed soil inhabiting fungus. The spore of M. anisopliae can be formulated as dust and sprayable formulation. It is used to control termites, mosquitoes, leaf hopper, beetles etc.
  16. 16. Nomuraea rileyi Nomuraea rileyi is of cosmopolitan occurrence and pathogenic to a number of economically important lepidopterous pests. It is formulated as wettable powder. The fungus could be multiplied on polished rice grains and crushed sorghum.
  17. 17. ORGANISM TRADE NAME TARGET PEST Beauveria bassiana Dispel®, Naturalis®, Mycotrol®, BotaniGard®. Helicoperva, spodoptera, borers, hairy caterpillars, mites, scales, etc Metarhizium anisopliae Taenure® Thrips and beetle larvae Tick-Ex® Grubs and ticks Paecilomyces fumosoroseus PFR-97® Whiteflies, aphids and thrips. Other genera- Nomuraea, Entomophthora and Zoophthora. – affects insects.
  18. 18. Metarhizium anisopliae
  19. 19. VIRUS Insect virus Baculo virus NPV GV CPV OCV
  20. 20. BACULOVIRUSES  Baculoviruses are rod-shaped, double stranded DNA viruses that can infect and kill a large number of different invertebrate organisms  Immature (larval) forms of moth species are the most common hosts, but these viruses have also been found infecting sawflies, mosquitoes, and shrimp.  Baculoviruses have limited host ranges and generally do not allow for insect resistance to develop  Slow killing of target insects occurs  In order to speed killing (enhance effectiveness), several genes can be expressed in the baculovirus including diuretic hormone, juvenile hormone esterase, Bt toxin, scorpion toxin, mite toxin, wasp toxin, and a neurotoxin.
  21. 21. BACULOVIRUS  Larvae infected with GV and NPV usually die within 5-12 days after infection.  These viruses are produced on the host insects and are formulated both as liquid and dust formulation.
  22. 22. family: Baculoviridae Nuclear Polyhedrosis Virus (NPV), Granulosis virus (GV) and Oryctes Granulosis virus.
  23. 23. NPV  NPV viruses develop in the host cell nucleus where one or several virus rods occur singly or in groups encased in a envelope.  The envelops are occuled in many-sided crystals called polyhedra.  After ingesting the polyhedra, larvae show no outward symptoms for 4 days to 3 weeks.  At this time, the larval skin darkens & larvae climb to the highest point on their host plant, where they die.
  24. 24.  Dead, blackened larvae may be found hanging from the tops of plants.  The integuments of these dead larvae rupture, and millions of polyhedra are released into the environment.  Such diseases collectively – caterpillar wilt.
  25. 25.  Seven virus registered with EPA.  NPV microbials – celery looper, gypsy moth, douglas fir tussock moth, corn earworm & beetle army worm.  Two GV microbials – codling moth & Indian meal moth.  NPV -250 – 500 ml/ ha 2 - 3 time at 10 days Interval
  26. 26.  Being obligate, virus has to be produced only in live insects.  Thus, for the production of HaNPV, either rear H. armigera on large scale or collect the larvae from field and use them for HaNPV production.  Collect the 250 larvae (6- 7 day old) of H. armigera from field. Production of HaNPV
  27. 27.  Larvae are singly placed in plastic tubes containing food contaminated with NPV.  After 7-8 days collect larvae showing the symptoms of NPV infection before they liquefied, in air tight container.  Keep this container for 8-10 days to decompose the larvae, so that polyhedra released from infected tissue.
  28. 28.  Homogenize the decomposed suspension of diseased larvae using a homogenizer.  Dilute the homogenized content with small amount of water and filter through two layers of muslin cloth.  Little water is sprinkled 2-3 times over the remnants to extract residual polyhedra.  For crude preparation the filtrate is diluted with water to make solution of 250 ml.  This is known as 250 LE (LE-larval equivalent) HaNPV  HaNPV in stoppered bottle, and store in cool and dry place. Cont……
  29. 29. ORGANISM TRADE NAME TARGET PEST Spodoptera exigua NPV SPOD-X Spodopteras- beet army worm Helicoverpa NPV Semstar Helicoverpa – tobacco bud worm, corn earworm Cydia pomonella GV ViroSoft Codling moth Chilo infuscatellus GV Shoot borer
  30. 30. PROTOZOA  Single-celled animals.  Some of them parasitize and kill insects.  Formulated as baits.  When bait ingested- protozoa spores – active- grow and replicate in the insect’s digestive system- kills.  Effective – insects in immature stage.
  31. 31.  Nosema locustae  Nolo Bait ®, Semaspore Bait ®, Hopper Stopper®  Grass hopper nymphs, Morman crickets

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