 Hi, welcome back to the course on Integrated Pest Management. After understanding the two important biocontrol agents that is predators and the parasitoids, now let us go into the third biocontrol agent that is use of microbial pathogen in managing the pest. We know that like all other organisms, the insects also suffer from various diseases. It is our prudency that using some of these diseases in the biocontrol program in managing the pest species. So, there are four major groups of microbial pathogens that we see like they are the fungi, the viruses, the bacteria and nematodes. So, in this class let us look at the fungi and the viruses which are quite important and also the bacterial group and what are there, the mode of action and how some of these have been used in managing the pest species. If you look at entomopathogenic fungi, so there are over 950 species which are pathogenic to the arthropods. Some of the symptoms of the fungal infection which we commonly look at and then try to identify the causal organism, one is that the insects which are infected with fungi will show the loss of appetite and they have an irritability and also the paralysis they will show. Initially there will be a discolored patches appearing on the cuticle of the integument and then the body later once it dies becomes hardens and covers with the dense white mycelial mat. So, at the end, so the body will be quite hard and it is mummified and either they will adhere to the substratum like leaves, stem or the fruiting body with an upright position and they will die. The death normally occurs within 4 to 7 days depending upon the host insect and also the environmental condition. In this slide we are going to look at the mode of action of this entomopathogenic fungi. How exactly? Generally, the fungi if you look they produce the spores and these tiny spores will be carried over either by wind or the water and then they settle on the substratum and whenever they come in contact with the insect cuticle then they start their action. If you look at it, the first step will be the adhesion of the spores to the host cuticle and once they are adored then the spore will start germinating and produces the hyphal bodies or the mycelia we can say and these mycelia will penetrate the cuticular structure of the insect and gets into the hemo seal and the hemolymph and where it produces certain toxins and which kill the cells in it and then ultimately kills the whole insect. Then after the death then the mycelial growth will produce and they actually grow as a saprophytical. Then when all this hyphal body will actually produces insides and it will emerges out and ultimately after completing the vegetative phase of the growth then it enters into the reproductive phase where it sporulates and millions of these spores will actually produce and again they will be carried and dispersed through the wind and the water. Now what are the important the fungal species that have been employed in the bio control program? If you look at it, there are 4 or 5 very important to fungal species one is the metrizium anisopliae which are commonly referred as green muscardin fungus and they are quite effective against the choleopterans, the soil inhibiting insects, some of the lepidopterans also and also the grasshoppers and other hoppers. Then the second one is the Bavaria basiana which is referred as the white muscardin fungus is quite effective against the lepidoptera, the choleopterans and some hoppers. Verticillium lacani is another important which is referred as white hollow fungus is usually effective against the scales. Then the pneumonia relay is also a very important defungi which actually affect the lepidopteran and as well as some of the sucking pest. And the Hirsutela thamsoni which is quite specific against the coconut mite and it has been used in managing the coconut mite, metrizium anisopliae so which can be used either as a spray or as a soil application, if it is an spray it can be used at the rate of 1 to 2 kg per acre or 10 to 15 kgs can be mixed with 50 kg of FIM or the vermicompost and then applied to the soil. Similarly, the Bavaria basiana 0.4 to 1 kg per acre as a foliar spray, verticillium lacani also of the same rate as well as the pneumonia relay and Hirsutela thamsoni against coconut mite can be used at the rate of 1 to 5 grams per litre of water per pump. Now let us go to the another important biocontrol agent that is entomopathogenic viruses. The entomopathogenic viruses especially those which comes under the family baculoviridae are effective against insects and they have been exploited. There are two types of virus which are quite common that we see, so one is a nuclear polyhydro viruses which are normally referred as NPV and there is a granuloviruses which is normally referred as GV. And among these two the NPV is most effective and quite widely been used even production and application of this NPV is normally done. Now let us look at the mode of action of a virus, so this NPV I will take an example of NPV. The NPV which is a nuclear polyhydro virus which normally contain an proteinaceous coating which is a polyhydral body inside which we see these the virions and these when they are actually fed by the insect and these polyhydral bodies enter into the gut system and at the mid-guit region because of the alkali pH what happens this polyhydral body will be dissolved and then they releases the virions and these virions they go and then bind themselves with the mid-guit epithelial cell. So here once they bind them then they will actually make a perforation and they will start sending the nuclear material into the cellular nuclear material and then it binds with the host nuclear material and it starts replicating and producing the viral bodies and these viral bodies are produced inside the host cell and then the few of these virions they will get embedded with the polyhydral bodies and ultimately it leads to the death of the whole cell and after leading to the death of the cell which leads to the death of the host then these polyhydral bodies will be released outside and then so they will again disperse and then infect the other insect larvae. Some of the symptoms of these entomopathogenic virus so again the larvae will become sluggish sometimes they change the color to the pinkish and then they lose the appetite then body becomes very fragile and rupture to the release of the polyhydral bodies so the whole body will be containing the polyhydral bodies and quite soft and even with a slight mechanical aberration the body will rupture and the polyhydral bodies will be released. Now especially the NPV will show a very typical symptom of what is called as the tree top disease so here you can see it here the larvae which is infected by NPV will usually climb to the top of the tree and then by adhering to the substratum with its prolegues then it hangs down so that is why it is referred as a tree top diseases. Now some of these NPV the main characteristics of this virus is that they are quite specific to a particular species so some viral bodies or the viral group which are specific to a certain species of insect cannot be used like the another species which is a huge advantage. For example, for field application we are using the NPV against helicorparamutera which is referred as HA NPV and in these cropping ecosystems like vegetables and the field crops we can use it at the rate of 200 LE per hectare that means LE means it is a larval equivalent so this is a recommendation given and similarly for podoptera litura NPV it is used in ground nuts, tobaccos, soybean or cotton ecosystem at the same rate. Similarly we have in methamnose separator NPV then amsat albistrega NPV which are quite commonly produced and then marketed. Now coming to the third important biocontrol agent that is entomopathogenic bacteria now entomopathogenic bacteria is quite popular as during the early 90s so by the discovery of a particular bacteria which is called bacillus thuringiensis then there is a lot of commercialization of this bacteria and they are utilizing in the pest management strategies. We can classify the entomopathogenic bacteria into two forms as the spore formers and the non-spore formers. Under the spore formers you get certain obligate bacteria and the facultative bacteria obligate bacteria like bacillus populiae and the populiae which is effective or used against the populiae japonica. Then under facultative you have again two form the one where they produce the toxin which is crystalliferous toxin and another one is a non-crystalliferous one. In this bacillus thuringiensis which I just mentioned which comes under the crystalliferous toxin and this is quite effective against many of the leopardopterons, choleopterons and the dipterine groups of insect. Under non-crystalliferous we have bacillus seraceous which is effective against hymenoptera and choleoptera. Under non-spore formers we have seracea marcesans which is effective against the leopardoptera and the hymenoptera. Now let us look at the mode of action of a bacteria by taking an example of bacillus thuringiensis. The bacillus thuringiensis as I explained produces the crystalliferous toxin in its cell or in the spore and these spores will have contain the spore and as well as the crystal body which contains the toxin and this when usually when an insect feeds on this will enter into the midget region and again due to the alkaline nature of the insect midget what happens the endotoxin which is present will be released and this toxin will actually go and binds with the epithelial cell of the midget and once it binds it here it causes the pores or the perforations and through which actually the cell will makes an entry and once it enters then it kills the insect cells by septicemia and after killing it then what happens it multiplies and produces in large number and then it will be released. Now some of the important the bacterial species which were employed here are the BT that is the bacillus thuringiensis and then bacillus sparricus and as well as pseudomonas fluorescence is another group of bacteria which is normally used. Then what are the symptoms of the bacterial infection as soon as the crystalline body releases the toxin in the midget then there is a rupturing of the midget epithelial cell takes place as a result the insect stops feeding immediately. And then there is a regurgitation and diarrhea due to the gut paralysis and later when the cells enter and kills the host body cells then the body becomes dark with a dark body fluid and tissue will be disintegrated and so that is how the death of the insect is going to occur. So in this class we understood about some of the important microbial pathogen which can be employed in the pest management. So in the next class let us look at the other bioagents that is other microbial agents and also the limitations and advantages of the bio control thank you.