In both pest resurgence and secondary outbreaks, their natural enemies were more susceptible to the pesticides than the pests themselves, in some cases causing the pest population to be higher than it was before the use of pesticide.
Izguba plenilskih vrst lahko povzroči povezan pojav, imenovan sekundarni škodljivčev izbruh in povečuje težave, ki izvirajo iz vrst, katere niso bile prvotno zelo škodljive in so to postale zaradi izgube njihovih plenilcev ali parazitov.