very few and unless you are bringing in pounds of seeds rather than a few seed packerts, you should have now issues..
That said, you can buy pretty good quality seeds here and save a lot of headaches.
Also, you have to make sure the varieties you bring in are adapatable to the shorter days inthe tropics...for example while good hybred corn will grow here, it won't produce like in Iowa since the days are a good bit shorter...
But a few packets of seeds should be okay...
HB