What kind of limited factor is parasitism considered

According to several research scientists, biological control (using either parasitoids or predators) is by far the best environmentally safe insect pest management method. However, performance (overall parasitization or predatory potential) of a biocontrol agent can often be hampered by either biotic or abiotic factors inducing failures of the biological control program implemented. Hence, logically speaking, ensuring success of a biological control program against an insect pest would necessarily require appropriate analysis of and finding practical solutions for these limiting factors. 

I think the answer is Microevolution