They occupy a very similar ecological niche, and thus compete for resources. By having a strong population of natives and EHs, the resources for AH are restricted, and makes their establishment more difficult.
These two threads are worth a read
rubbish!
Last time we had mass queen wasp die off was in 2012 and before that 2004. It's not unusual. Mild winters and inclement Springs and early Summers are very challenging for wasps. I disturbed a germanic nest in a pile of rubble whilst working on a garden project and it was at least a month behind development wise.
So a corollary from that study could be that wasps form a large proprtion of their diet, and that wasp nests act as a decoy for bees...
Thank you for this link. It's certainly an interesting paper. I don't think there are any surprises in it but it is good to see corroboration of what is generally understood of velutina's diet.
The bit that is missing is the size of the nests when sampled. A 50% wasp diet in a vastly under populated velutina nest is a good thing. It shows that velutina is struggling to find easier more abundant prey and small numbers of wasps taken don't reflect casualty rates amongst hunting velutina which creates a very positive feedback loop. The more hunting hornets that don't make it back, the more the remaining hunting hornets are forced to go for wasps the less resources get to the development of larvae and sexuals.
Thanks for the additional insights. Huge value.
Similar niche and diet, yes, but I am inclined to think that a strong population of native wasps simply provides a better buffet for AHs.
Why so? The video clip I linked to earlier shows how wasps destroy hornets hawking at the nest.
The defensive behavior that the wasps show in the video is the same that the Japanese honey bee has with respect to the mandarin hornet or the one that my bees displayed when I dropped a partially knocked out velutina and it is the same that the nurses show when they want to eliminate a unwanted queen in one's own hive. The curious thing is that this behavior has nothing to do with who eats whom.
Not sure that's entirely true.
I don't think bees lose their sting and associated innards when they sting something soft like a wasp?
By and large they don't, that's true. The architecture of the stinger is quite fascinating and is made up of three linear elements, namely the stylet and two lancets. When hymenopterans sting the lancets alternately slide up and down the stylet in a sawing action and venom is pumped along the channel created between the three elements. The barbs on the honeybee lancets act to reduce the penetrative pressure required to puncture tissue so honeybees are able to sting more easily than wasps which don't have barbed lancets. However, the down side is that the force required for the honeybee to extract its stinger is considerably greater which makes it harder for the honeybee to detach itself quickly leaving the honeybee open to counter attack. So, even though the honeybee may not lose its stinger, it will quite likely sacrifice itself in the attack as a consequence. Wasps on the other hand require greater force to drive their stinger into their victim but they have the advantage of being able to quickly detach, i.e. able to conduct multiple hit and run attacks. That being the case, wasps defending their nest are far more capable of overwhelming hornets and it takes far fewer wasps to do so.
