Questions about guppies?

I have 3 females and 2 males. 2 of the females were pretty spunky when I first got them but now they aren't begging for food with the rest of them when I feed them. They stay at the bottom and pick at the gravel where the food floats down instead. I'm worried that they won't get enough food to eat this way. Also the two males constantly pester the females, especially during feeding time and I'm afraid they aren't letting them eat. Is it normal for them to constantly harr the females like this? They seem to prefer the 2 females that aren't eating much for some reason, could the harrment be why they aren't responding when I put food in the tank? None of the females are responding to their wooing and run from them every time..