 Hi, welcome back to the class of biological control. So, in the last class, we knew about the biological control, its definition, little bit of history, then the concepts and one of the important biocontrol agent that is a predator, their groups and their importance. Now, in this class, let us know about another important biocontrol agent that is a parasitoid and what are the different categories of parasitoids we get based on the different parameters and some of the important parasitoids which have been employed in the biocontrol program. So, what is a parasitoid? So, this is little bit confusion which occurs because we all are quite familiar with a word called parasite and then what is this parasitoid? So, the parasite if you actually define it is an any organism which take shelter in another organism which we call it as a host for its food and the protection, but however in parasite it actually does not lead to the death of the host whereas, the word parasitoid which has been coined in insects is especially those organisms which either any of their stages in the life cycle which take shelter and the food on the other host which we call it as a prey and ultimately kills it. So, the most important difference that we get between a parasite and parasitoid is that in case of parasitoid there will be an ultimate death of the host which occurs. So, some insect groups we actually identified which are quite potential parasitoids on the insect groups or the defoliators or the past herbivores so, which we actually utilize them in the biocontrol program. Now, what are the important qualities that we have to look into while selecting a parasitoid? Some of the important characteristics of parasitoid it should have a very good host searching capacity because so, it should actually seek the host and then parasitize it then only we get a good control and it should have a host specificity in the sense it should basically a major parasitoid on the key pest on which that we actually is been released or recommended it should have an universal adaptability in the sense a wider adaptability for the parasitoid in order to withstand the abiotic and the biotic factors it should have a good dispersal ability that means after multiplication this parasitoid should be able to disperse itself and find the other host and then controls it then it should be an amenability to the mass culture which is quite important in the sense so, it should be easily mass cultured under the laboratory condition so, that we can release it in enormous number in the field it should also be able to withstand the computation with the other species of parasitoids and also should have an ability to outnumber the pest that means it should have a quick multiplication rate and so, that it suppress the pest within a shorter period of time and a better survival capacity is also an very important characteristic of an insect parasitoid. Now, so, another important aspect that we actually should know is a difference between a parasitoid and a predator so, which organism we call it as a parasitoid and which we should call it as a predator so, the important differences are given here so, in this case so, look at a predator and a parasitoid always in case of predators they are bigger than their prey whereas, in case of parasitoids they are smaller than its host in case of this the organism on which the parasitoid take shelter we call it as host and usually predator will be very active because it has to actively seek the host kill it and then feed it generally the parasitoids initially they will be active, but once they actually starts colonizing on the host then they will be sluggish and then they will start feeding on it. In case of predators the organ of locomotives and the sense organs and as well as the mouth parts are well developed whereas, in case of parasitoids so, they are not so well developed because they will be either taking shelter inside or outside the body of the host. Then habitat in case of predator is independent of its prey it means they will be living some way whenever they want food they come and then feed on the prey and then they go back to their habitat whereas, in parasitoids because it is a constantly in association with the host so, the habitat will remain same and life cycle in case of predator will be longer one whereas, here it should be a shorter because it has to complete its life cycle before the completion of a particular stage of the host. In this case a single predator may actually attack a several host in a shorter period that means it feeds on more number of individuals whereas, in parasitoids it usually develop on a single host. Now, let us look at the different types of parasitoids that we get so, these categories of parasitoids can be made based on certain parameters. For example, based on the developmental site in the host they may be classified as an ectoparasitoid or endoparasitoid. So, ectoparasitoids are those species where the immature stages or the developmental stages are found on the host itself. Say like you can see here this is the host on which we are seeing the grubs or the immature stages of the host I mean the parasitoid which are feeding on it. So, this you normally see it in a species called brecon brevicornis on the coconut black red caterpillars. The endoparasitoid is those groups where the feeding stage are found within the body of the host and they are not been exposed. So, that is one category that we can make it. Similarly, so based on the stages of the host attacked so, they may be called as an egg parasitoid. So, wherein the parasitoids only attack the egg stage of the host like the trichogramma species that you are seeing. So, they actually lay the eggs on the eggs of their host and on which they complete all the development and adult will come out. Most of the trichogrammatid species and as well as cilionid species they are an egg parasitoids. And this is quite useful because so they are going to kill the host which are actually the past in agricultural ecosystem well before they start actually causing the damage. Then the second one is an egg larval parasitoid. In this case the parasitoid will lay the eggs on the eggs of the host, but however they will continue their life cycle and then they emerge when the host becomes in larval stage. This you normally get it in some breconidae and as well as some n-thertidal. Now, the third one is a larval parasitoid. This is a most common the parasitoids that we get and the large species of parasitoids will actually come under the larval parasitoid. In this case, so they lay the eggs on the larval stage, the development of the parasitoids takes place on the larval stage and the emergence will also takes place on the larval stage. Some good example that we give is a Bethelidae. It is a Gonioses nephantides that you are seeing here a serious good parasitoid on the coconut black headed caterpillar and Campolitis chloridae and the ignimunidae group is also a larval parasitoid and at the plastic yesterday, so you also get a good parasitoids. Similarly, we can also have another group that is a breconidae which is quite common a larval parasitoid seen on many of the insect pests. Then the fourth group that we can make is a larval pupil parasitoid where the parasitoid lay the eggs on the larval stage but the adults will emerge when the host will enter into the pupil stage and the fourth category you get is a pupil parasitoid where the parasitoid mainly attacks the pupil stage of the host and it completes its development. Chalcedidae is another group which is a pupil parasitoid and apiricanidae is another group which is a pupil parasitoid. Then you also have the nymphal and adult parasitoid in the sense that these parasitoids mainly attacks the bug group that is at the nymphal stage and as well as the adults of the hemipterans. Some of the dipteran groups also you do get as a larval pupil parasitoid such as Sturmyopsis inference, so which is quite commonly used in the bio control program. Now, based on the host specificity, so the parasitoid can be classified as a monophagous parasitoid, oligophagous parasitoid or a polyphagous parasitoid. In case of monophagous parasitoid, they are highly host specific attacking a single host species. It means they are quite specific and if you are actually released on a particular species they only take case or they control that one. For example, the paraciorla nephanthides which is a monophagous parasitoid on opicina arenosella that is a coconut blackhead caterpillar and there are other groups of parasitoids which are oligophagous that means they have a restricted group of a related host species on which they parasitize. But some parasitoids are polyphagous they attack wide variety of the host species such as the trichograma species which is an egg parasitoid that we have seen. For one of the successful biological control program, so we have to choose this type of the parasitoid which type of parasitoid that we need either it should be a monophagous, oligophagous or the polyphagous. Next the fourth category is it can make it based on the host as the primary parasitoid, secondary parasitoid or the tertiary parasitoid. A primary parasitoid is a one which actually a parasitizing a pest so which we call it as a primary parasitoid whereas secondary parasitoid it is a parasitoid which attacks another parasitoid. But this is quite harmful we cannot use it in the bio control program whereas the tertiary parasitoid is a parasitoid which attacks the secondary parasitoid and this is quite useful to us. So all parasitoids whose hosts are parasitoids are referred as the hyperparasitoids. Now the fifth category is like based on the number of parasitoids that are developing from a single host so we can classify it as a solitary parasitoid or as a gregarious parasitoid. Solitary means a single individual will comes out from a host. So this is the one whereas in gregarious parasitoids the several processes are completing its development on a single host so like this. Now based on the kinds of parasitism we are classifying it as a simple parasitism, super parasitism and multiparasitism. Simple parasitism is applied when there is a single attack of the parasitoid on the host irrespective of the number of eggs laid. It might lay a single egg or it might lay several egg but there is a single attack. Super parasitism when many individuals of the same species attack a parasitoid on a single host then it is called as a super parasitism. Multiparasitism its attack of a parasitoid on an insect host which has already been a parasitized which is not quite good for the bio control program. Now some of the important parasitoids which have been recognized they are mass produced and their dosages also have been fixed against certain crop pests. For example the trichogram of pichelon is a very useful egg parasitoid which has been used against the chute borers or the stem borers and it should be released at the rate of 1.5 to 2.5 lakhs per hectare. There is another egg parasitoid trichogram of japanicum which is recommended against yellow stem borer in paddy is also recommended at the same dosage. Similarly the goniose of snafantis which is an as larval parasitoid is used at an inoculative rate of about 15 to 20 individuals or the adults per plant. Similarly we have bracon bevicornis, bracon habitat, cologneis blackburning, then the cotesia pollutella and all these they have been multiplied and artificially they are released into a different agricultural ecosystem at a different dosage. And if you look at these dosages some are actually the inundative release where we actually they release it in order to get a quick control and whereas in some cases we have an inoculative release where this is actually followed in a perennial ecosystem for a slow and steady control. So far so in this class we studied about the parasitoid, their categories and their qualification. So in the next class let us look at another important biocontrol agents that is the microbial pathogen and study about their categories their mode of action and some how they can be implemented in the integrated pest management. Thank you.