We all know anoles eat LIVE insects! Not all insecticides/pesticides will kill the insects right away. Some take days to kill the insects. The insects will be poisoned and become less alert and have slower movement before death.These insects are easy pickings for hungry lizards who then injest the insecticides/pesticides that were on/inside the insects.
Now if you know there are no pesticides in your area that risk is reduced but a lot of areas spray for mosquitos now because of west nile.
Anyway I have NEVER seen an adult brown/green anole able to fight off a yearling snake. I am sure it is possible but I have never personally seen it. I had a WC hatchling black rat some years ago that would only accept anoles. I tried for weeks to shift him to pinkies but he just wouldn't budge until he was a little older.(anole scented pinkie parts helped) Now this guy was only 12-14 inches long and would tear adult male anoles up. They would fight him back and throat fan before he approched him sure but the snake always won quickly. Once that snake was around that anole it was always over. The anole would clamp on to him for dear life but never won.