[erutuon]

Drinking nectar doesn't necessarily mean pollinating, that is transferring pollen. The pollen has to stick to the insect's body and the insect has to visit another flower that is genetically compatible and the pollen has to get stuck to the stigma of that flower when the stigma is gooey and receptive.

Some flowers can only be pollinated by insects of particular sizes or shapes because of the position of the pollen-producing (anthers) and pollen-accepting (stigma) structures, and some insects bypass pollen entirely by biting a hole in the base of a flower to drink the nectar, and some insects don't visit multiple flowers of the same species consistently enough to transfer pollen (honeybees for instance apparently) as efficiently as other insects (bumblebees).

Most wasps (of which hornets are a subtype) are only interested in nectar, not pollen, and some flowers don't produce nectar so won't be visited by wasps. Most wasps have short tongues for their body size, so they can't access some flowers that bumblebees can (bumblebees have long tongues). Some bees (bumblebees or mining bees for instance, not honeybees) buzz their wings to extract pollen from particular flowers like blueberries and tomatoes, enabling them to be pollinated effectively, and wasps don't do that.

So giant hornets can't do all pollinating that bees can do. However, in the upper Midwest the spotted bee balm (Monarda punctata) is pollinated by large wasps, so there might be other flowers in the area invaded by giant hornets that could be pollinated by them.

Disclaimer: I'm an amateur, not a scientist with a degree.

[erutuon]

Whoops, the article is about the Asian hornet, not the giant hornet... but my comments still apply.

[guenthert]

I presume that's all true, but is that actually relevant? Aren't hornets much more rare than even bumblebees, not to speak of bees in general?