I don't know about seeds carried on someone's person, people probably still slide them in their sock and walk it through. The mail is more what I refer to here. Bees, yeah, they probably don't take customs too seriously. lol
A little off topic but...interestingly, I took my kids last year to a facility dedicated to educating people about how problematic exotic pets are. It's more or less a rescue that takes in confiscated animals, often of the dangerous variety. I was shocked to see they had - not terribly far from where I live relatively speaking - an alligator, crocodile, several huge pythons (20 feet long), African porcupine, monitor lizards the size of alligators, etc. They were all smuggled in, via air of course, the reptiles sometimes in a bottle of Pepsi or other such beverage, that they brought on board. Crazy!