Kinda misread it :p !
Incentives are the heart of HK and farming wars isn't an exception, eradicators have a big incentive to help other players as the leaderboard (which is essentially a pool like raids or a mota pool) will reward them for eradicating plagues which will be essentially eradicating plagues from others player's land plots.
So you can choose to not participate and leave everything to your partner's eradicators but you won't either earn the extra BUDS from the pool or the EXP or have the chance to collect the plagues after eradicating them with a pesticide, all those new rewards will be for the eradicators that are interacting in the ecosystem.
Second, we haven't posted the numbers of how many nano gears will a pesticide cost or a plague cost, or even how many nano gears will be produced by the factories but feel safe that won't be enough to have a overpopulation of plagues as there's not overflood of water ;)