There will be no alert, but you will be able to see the enemy icon on the map, something you wouldn't without one.
That's why it is very important to keep an eye on the minimap to make sure you know where your enemies are, and then warn your teammates if they are in danger.
Originally Posted by ImASpicyJalapeno
I actually ward in intermediate bot matches but there is no point in doing it for beginner bots. I always chuckle when I see people buying sightstones in beginner co-op games
That's not nice.
I could say
"I always ward in ranked, but there is no point in doing it for normals. I always chuckle when I see people buying sightstones normal games
Is that nice? No.
You are implying that people who play intermediate are better than people who play beginners, (same way on my example I am implying people who play ranked are better than people who play normals, and both are not nice).
People are free to play however they want in whatever game mode they want, as long as they are not making the game unpleasant to other players.
and FYI, even beginner bots roam, gank and walk through jungle, after a tower is down, so it is not useless to have a sightstone.