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human
How does host selection work for different species of parasitic wasps?

There are thousands of species of parasitic wasps, and they have a diverse range of hosts for which they lay their eggs in, such as caterpillars, spiders, aphids, etc. However, could, for instance, a tarantula hawk wasp be able to lay eggs in a caterpillar, and just prefers targeting spiders, or can it only lay eggs in spiders? Same question applies for other types of parasitic wasps.
gpt
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 😈