The ants don't eat your leaves, they do eat the honey dew from aphids or scale, a common problem with citrus. I spray with horticultural ultra fine oil, three times, about a week apart. Get both sides of each leaf. Only spray when the weather is cool. Dead edges of the leaves could be caused by a buildup of salts in the mix caused by not watering enough at each time to flush out the mix. It is best to see about 15% of the water you use, exiting the drain holes. Al

i've also seen them eating the nectar from the flowers.