Chapter 13 - Enhanced Biological Control through Pesticide Selectivity

Abstract

This chapter discusses direct and indirect effects of pesticides on natural enemies, the consequences of disrupting biological control, and approaches to reduce the negative impact of chemicals on natural-enemy populations. Direct effects include short- and long-term impacts on natural enemies due to direct contact with pesticides or pesticide residues, and indirect effects are those in which the impact of the pesticide is mediated through the natural enemy's host or prey. Indirect effects may be caused by reduction of host or prey populations that serve as food sources for natural enemies, a change in the host or prey distribution, and ingestion of pesticide-contaminated prey or hosts. Unilateral chemical control of arthropod pests can result in population explosions of both target and nontarget organisms due to various reasons, including hormoligosis, pesticide resistance, and the destruction of natural enemies. The best method for reducing the overall negative impact of chemicals on natural enemies is to avoid pesticide applications altogether. Pesticides used in the management of pests should be applied only when necessary and economically justifiable.