There is a containerized garden method known as air pruning using cloth or bags. the idea is that the
roots will grow to the edge of the porous container and stop then they reach air exposure. So you can grow in soil that has exposure to air; and the plants will grow to the point conditions are favorable.
Short
answer is yes, you can holes in your
bucket and it will not negatively effect the roots. Insects attack the above ground portion of plants. There are 'insects' that attack roots, but they live in the soil anyway/already. having a hole in a bucket will not influence their behavior.
Often times pots are given holes in the side to utilize the sides to plant into, allowing more surface area/plant density in the same container. Think of a strawberry barrel, where plants are inserted into the sides as well as the top.