Chapter 2
Biological Control of Parasites
Tebit Emmanuel Kwenti
Additional information is available at the end of the chapter
Abstract
Parasites (ectoparasites or endoparasites) are a major cause of diseases in man, his live‐
stock and crops, leading to poor yield and great economic loss. To overcome some of
the major limitations of chemical control methods such as rising resistance, environmen‐
tal and health risks, and the adverse effect on non‐target organisms, biological control
(biocontrol) is now at the forefront of parasite (pests) control. Biocontrol is now a core
component of the integrated pest management. Biocontrol is defined as “the study and
uses of parasites, predators and pathogens for the regulation of host (pest) densities”.
Considerable successes have been achieved in the implementation of biocontrol strate‐
gies in the past. This chapter presents a review of the history of biocontrol, its advantages
and disadvantages; the different types of biological control agents (BCAs) including
predators, parasites (parasitoids) and pathogens (fungi, bacteria, viruses and virus‐like
particles, protozoa and nematodes); the effect of biocontrol on native biodiversity; a few
case studies of the successful implementation of biocontrol methods and the challenges
encountered with the implementation of biocontrol and future perspectives.
Keywords: biological control, biological control agents, parasites, humans, plants,
livestock, case study, challenges1. Introduction
In nature, the population size of every species is regulated by natural environmental fac‐
tors. These factors are responsible for the “checks and balances” of a population of living
organisms. The event where living organisms live and die a natural death unaided by man is
termed “natural control”. Weather (abiotic or non‐living factors) is an important factor in nat‐
ural control; temperature and humidity are determinants of the survival of living organisms.
Availability of competition (biotic factors) is also an important determinant for the survival of
living organisms [ 1 ]. Many organisms are killed by pathogens (disease‐causing agents) such
as bacteria, viruses, fungi, parasites (parasitoids) and predators [ 1 ].