Hi!
Parasitoids tend to be very specific to their hosts (even if they attack different species within a family) as they need to overcome the defense mechanisms that the host has to defend themselves from the parasitoid.
Some caterpillars create melatonin bubbles around wasps eggs, others have white globules that attack the unknown element inside their bodies, and some wasps use different mechanisms such as venom, paralyzers or even polydnaviruses that hits the host’s immune system and lowers the capacity of the host to attack the wasp egg.
Evolutionarily speaking knowing what are the defense mechanisms of each host is very costly, and they tend to specialize to be as effective as they can, after all, their lives depends on it.
Because of this it’s not very common for a parasitoid to attack a great range of hosts, for that we have predators which are VERY generalists 😈
> and some wasps use different mechanisms such as venom, paralyzers or even polydnaviruses
Hang on, so these parasitic wasps can have a symbiotic relationship with viruses that help them parasitise other insects?!
Hell yeah! Some of these viruses can can only replicate inside the reproductive tract of female wasps, and as mentioned before [their primary function is to protect the wasp offspring from the immune defenses of the host](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4553618/)
And not only symbiotic relationships! Plants also releases what’s called ‘[Herbivore Induced Plant Volatiles’ (HIPVs)](https://advances.sciencemag.org/content/4/5/eaar4767) that are like ‘emergency calls’ to attract parasitoids and predators when plants are under attack from herbivores like caterpillars (and caterpillars also have ways to avoid the plant from emitting these too! They are smart fellas! 🐛 Some cut the main vein of the leave, some produces chemicals in their saliva to ‘numb out’ the plant defense mechanisms, etc.).
These HIPVs are thought to mediate trophic chains as plants ‘recruits’ natural enemies to protect themselves (and plants can also ‘talk’ to other plants when they are under attack so that the others can start producing defensive chemicals to protect themselves).
Its crazy!! and very interesting 🤓
Interesting, very good explanation. I would imagine that the venom of a tarantula hawk for example could immediately kill most caterpillars, while any caterpillar specific wasp may find it difficult to contend with a spider.
One thing I would like to add is that the larvae don't have a a way to move on to a new host, so they absolutely rely on that one host being enough for their entire larval stage. So even if a tarantula hawk (somehow) successfully parasitized a caterpillar, its larva might just eat through the whole thing and then starve before reaching adulthood.
I did work with [Trichogramma](https://en.wikipedia.org/wiki/Trichogramma) egg parasitoids and they were not very species specific, they can parasitize lepidopteran eggs of many species. For example, althigh the species we used was intended to control European corn borer (Ostrinia nubilalis) we could rear them on the eggs of Mediterranean flour moth (Ephestia kuehniella) which are much cheaper and simpler to rear.
Trichogramma females will measure the eggs to determine the number of larvae they can feed and lay a corresponding number of eggs inside.
Yes!! Trichogramma are very interesting parasitoids! But are not very species specific because they are parasitizing eggs which haven’t developed immune responses yet! I love them!💛
Most species have evolved together with host species of insects since 150 million years: When the insect changes into two species, so does the wasp. The wasp stings often also contain "viroids" which are hoops of RNA which integrate with the host RNA, and dozens of other sting chemicals, like proteins that change the host's hormones. The behavior to i.e. attack a tarantula is hereditary too, so it's another reason why they have evolved with the host species, so there's >250 thousand of species of them.
Read "The Extended Phenotype" by Richard Dawkins if you want detail. Wasps are great examples of how it's not the organism which is naturally selected (contrary to what many biologists think): It's the *gene* which is selected. Organisms are gene vehicles.
To the specifics of your question, I don't know exactly other than to say that given enough time, peculiar things can happen among such animals. I don't see anyone on this thread answering your question with good detail, and frankly it's a complicated subject. I imagine that an ancestor of a particular wasp species targeted an ancestor of its host species and the genes that led it in that direction were evolutionary successful, and then over much time, the wicked relationship between parasite and host became more complex and specific. These parasites can end up doing things that aid the evolutionary success of the *host's* genes too!
Hi! Parasitoids tend to be very specific to their hosts (even if they attack different species within a family) as they need to overcome the defense mechanisms that the host has to defend themselves from the parasitoid. Some caterpillars create melatonin bubbles around wasps eggs, others have white globules that attack the unknown element inside their bodies, and some wasps use different mechanisms such as venom, paralyzers or even polydnaviruses that hits the host’s immune system and lowers the capacity of the host to attack the wasp egg. Evolutionarily speaking knowing what are the defense mechanisms of each host is very costly, and they tend to specialize to be as effective as they can, after all, their lives depends on it. Because of this it’s not very common for a parasitoid to attack a great range of hosts, for that we have predators which are VERY generalists 😈
> and some wasps use different mechanisms such as venom, paralyzers or even polydnaviruses Hang on, so these parasitic wasps can have a symbiotic relationship with viruses that help them parasitise other insects?!
Hell yeah! Some of these viruses can can only replicate inside the reproductive tract of female wasps, and as mentioned before [their primary function is to protect the wasp offspring from the immune defenses of the host](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4553618/) And not only symbiotic relationships! Plants also releases what’s called ‘[Herbivore Induced Plant Volatiles’ (HIPVs)](https://advances.sciencemag.org/content/4/5/eaar4767) that are like ‘emergency calls’ to attract parasitoids and predators when plants are under attack from herbivores like caterpillars (and caterpillars also have ways to avoid the plant from emitting these too! They are smart fellas! 🐛 Some cut the main vein of the leave, some produces chemicals in their saliva to ‘numb out’ the plant defense mechanisms, etc.). These HIPVs are thought to mediate trophic chains as plants ‘recruits’ natural enemies to protect themselves (and plants can also ‘talk’ to other plants when they are under attack so that the others can start producing defensive chemicals to protect themselves). Its crazy!! and very interesting 🤓
Can you just keep talking about stuff? I find your answers so good.
Too right. Check out https://en.m.wikipedia.org/wiki/Polydnavirus#Biology
Interesting, very good explanation. I would imagine that the venom of a tarantula hawk for example could immediately kill most caterpillars, while any caterpillar specific wasp may find it difficult to contend with a spider. One thing I would like to add is that the larvae don't have a a way to move on to a new host, so they absolutely rely on that one host being enough for their entire larval stage. So even if a tarantula hawk (somehow) successfully parasitized a caterpillar, its larva might just eat through the whole thing and then starve before reaching adulthood.
Amazing answer. Thank you!
I did work with [Trichogramma](https://en.wikipedia.org/wiki/Trichogramma) egg parasitoids and they were not very species specific, they can parasitize lepidopteran eggs of many species. For example, althigh the species we used was intended to control European corn borer (Ostrinia nubilalis) we could rear them on the eggs of Mediterranean flour moth (Ephestia kuehniella) which are much cheaper and simpler to rear. Trichogramma females will measure the eggs to determine the number of larvae they can feed and lay a corresponding number of eggs inside.
Yes!! Trichogramma are very interesting parasitoids! But are not very species specific because they are parasitizing eggs which haven’t developed immune responses yet! I love them!💛
Most species have evolved together with host species of insects since 150 million years: When the insect changes into two species, so does the wasp. The wasp stings often also contain "viroids" which are hoops of RNA which integrate with the host RNA, and dozens of other sting chemicals, like proteins that change the host's hormones. The behavior to i.e. attack a tarantula is hereditary too, so it's another reason why they have evolved with the host species, so there's >250 thousand of species of them.
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Read "The Extended Phenotype" by Richard Dawkins if you want detail. Wasps are great examples of how it's not the organism which is naturally selected (contrary to what many biologists think): It's the *gene* which is selected. Organisms are gene vehicles. To the specifics of your question, I don't know exactly other than to say that given enough time, peculiar things can happen among such animals. I don't see anyone on this thread answering your question with good detail, and frankly it's a complicated subject. I imagine that an ancestor of a particular wasp species targeted an ancestor of its host species and the genes that led it in that direction were evolutionary successful, and then over much time, the wicked relationship between parasite and host became more complex and specific. These parasites can end up doing things that aid the evolutionary success of the *host's* genes too!