Successful
biocontrol programs usually significantly reduce the abundance of the pest, but in some
cases, they simply prevent the damage caused by the pest (e.g. by preventing it from
feeding on valued crops) without reducing pest abundance (Lockwood 2000). Biocontrol
is often viewed as a progressive and environmentally friendly way to control pest
organisms because it leaves behind no chemical residues that might have harmful impacts
on humans or other organisms, and when successful, it can provide essentially
permanent, widespread control with a very favorable cost-benefit ratio. However, some
biocontrol programs have resulted in significant, irreversible harm to untargeted (nonpest)
organisms and to ecological processes. Of course, all pest control methods have the
potential to harm non-target native species, and the pests themselves can cause harm to
non-target species if they are left uncontrolled. Therefore, before releasing a biocontrol
agent (or using other methods), it is important to balance its potential to benefit
conservation targets and management goals against its potential to cause harm.