Bonus Pest Chance

is a Stat that increases the chance for 2 to 4 Pests to spawn at once instead of 1 whenever a Pest would normally spawn.

Permanent sources

 * Wriggling Larva ( each, up to a maximum of )

Semi-permanent sources

 * on each armor piece ( per level, up to a maximum of each, or  total)
 * Using Mushroom Armor while it is night can triple this stat, resulting in up to total added  instead of.
 * Tip: You can place a Night Saver in your Garden to make it permanently nighttime.
 * Pesthunter accessory line (each level is an upgrade and does not stack with the previous)
 * Pesthunter Badge
 * Pesthunter Ring
 * Pesthunter Artifact
 * Slug Pet ( per level, up to a maximum of )

Temporary sources

 * Sprayonator for 30 minutes in the sprayed plot(s)

Decreasing Bonus Pest Chance
On the Alpha Hypixel Network, there was a Jacob Contest Protection mechanism that allowed you to disable during Jacob's Farming Contests, as well as an ability to toggle  on the Pesthunter accessory line, however these have both been removed before the update got released to the main Hypixel network.

There is currently no way to disable or decrease, aside from getting rid of things that grant it. The only truly permanent source is Wriggling Larvae.

You can remove from your armor using the Hex, however it is very expensive to reapply it again, so if you don't want to risk pests ruining your Jacob's Contests, is recommended to apply it to a secondary Mushroom Armor set, even though you lose out on up to  by not having the enchant on your primary armor.

Theoretical maximum
Using all of the above, the maximum that is known to be reachable is.