The basics of pest management

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With the current focus on the environment, information on pest management is a hot topic. Discussion of the subject is useful however, there is a great deal of confusion around some of the language associated with pest management.

First of all, what is a pesticide? Pesticides are materials used to control, destroy or inhibit pests. Consequently, the range of pesticides includes a wide variety of products. Health Canada’s Pest Management Regulatory Agency conducts thorough scientific evaluations to determine if a pesticide meets strict health and environmental standards before registering it for use and sale in Canada.

There are many different kinds of plant pests including insects, weeds and diseases. And there are many different kinds of pesticides, from horticultural oils, to insect growth regulators, to conventional products.

‘Narrow spectrum’ pesticides are designed to affect just a few pests. ‘Broad spectrum’ pesticides, as you might expect, affect a wider range of species. Both narrow and broad spectrum pesticides can sometimes affect non-pest species, however narrow spectrum products are less likely to do so.

You may also have heard the terms ‘synthetic’, ‘organic’, ‘chemical’, ‘natural’ and ‘biological’ used to describe various pesticides.

‘Synthetic’ simply means that the pesticide does not occur in nature though it may have been synthesized to mimic a naturally occurring substance.

The term ‘organic’ can be misleading because it is so commonly used to imply pesticide free. Contrary to what you might think, in the pest management world, ‘organic’ does include chemical pesticides and does not mean pesticide free. Chemical pesticides can be either organic or synthetic. The term simply denotes products that are approved by government for use in organic growing programs. Organic pesticides are, however, generally naturally derived compounds.

Finally, ‘natural’ and ‘biological’ pesticides are derived from living organisms. Products of these kinds are often and increasingly used in Integrated Pest Management programs because they are both effective and more environmentally sound. We often refer to these as ‘new generation’ pesticides.

Another confusing aspect of pesticides is the notion of ‘toxicity and modes of action’ or the ways in which various pesticides work. Some work simply by smothering, as in the case of horticultural oils. The rough texture of diatomaceous earth physically damages insect pests; kaolin clay creates an unpleasant environment encouraging them to move on. These are generally not very toxic to non-target species. Some ‘older generation’ insecticides, developed after the Second World War but still in use today, are ‘nerve poisons’ and can be quite toxic to humans. These are falling out of favor in ecologically based IPM programs because of their broad spectrum impact, including humans. Various herbicides work by either burning foliage, or disrupting the internal workings of weeds and some may be toxic to humans.

Another term you may have heard is ‘soft’ which simply means less harmful to ‘good’ insects such as ladybird beetles and lacewings, and less likely to persist in the environment after doing their work. Most new generation pest management materials are soft.

Pest management is rapidly changing. Increasingly, methods and materials that are biologically based, ecologically sound and environmentally safe are preferred. The bottom line is that any pest management program should have environmental and human health in mind, first and foremost.