I was out tonight walking a frog (found it hung up in a tree limb awhile ago so I don't know which brand), and I happened to notice as soon as the sun got 90% set if any bass hit the lure they just kinda tugged on it instead of blasting it like earlier in the day. Do bass 'shutdown' a little when there is little light? Would adding a rattle or a couple bb's help for the fish to better locate the lure. I'm curious because I've chosen to focus on topwaters this season and want to maximize my chances of landing fish.

Thanks,

Coak

Bass are mainly sight feeders and low light makes for poor visibility on their part. Under low light such as dusk or dawn they rely more on their other sences to locate their prey.  Top water presentations, with the exclusion of buzzbaits, are difficult for an angler to maintain a steady cadence which aids a fish in it's ability to inhale it.  Rattles will help them locate the bait, but it's doubtful they will attack it the same as during the day or later in the evening when they can silouette it against the night sky. 

You're talking about a very short time frame when the sun is just about to break the horrizon. If you want to stick with a topwater presentation during that time, I suggest a buzzbait.  They'll hammer them things morning, noon, and night not to mention just about anytime inbetween.