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Chapter 1
Current Approaches to Biological
Control of Agricultural Insect Pests
1.S. KELLEHER
This part covers the biological control of insect and mite pests of crops, fruit trees, and
ornamentals. As in the previous review (Kelleher 1971) it includes inoculation
(introduction), augmentation, and inundation, using beneficial insects, entomopathogens,
and autocidal methods.
Some organizational changes have occurred since the last review. In 1972, the
Research Institute at Belleville, Ontario, was closed and the staff transferred to
Research Stations in other parts of Canada. The service function, of obtaining
infonnation and collections of biological control organisms from abroad was transferred
to Ottawa. The programme on the biological control of weeds was moved to the Regina
Research Station. An Integrated Pest Control Section was fonned at Winnipeg with
many of the scientists from Belleville. Other individuals were stationed at Summerland,
Saskatoon, Harrow, and Ottawa.
The adoption of integrated pest management (IPM) systems has placed biological
control in a much more important role than before. At one time it was considered as an
alternative to chemicals i.e. complete control was necessary. Now, however, our
knowledge of insect population dynamics has increased, and it is now considered that
even a small additional percentage mortality can have a profound effect on the overall
reduction of an insect population.
The initial stages of an IPM programme involve a reduction in pesticide usage, by
monitoring pest infestations so that chemicals are applied only when necessary. As a
consequence, natural control factors are not so suppressed and are able to exert
additional mortality on the pest population. But there will be a point where very little
more can be obtained from the systems available and additional factors must be added
to attain a greater reduction in pesticide use. This can come in many forms but the
introduction of new natural enemies should be an important consideration in many
instances.
Most of the studies reported in this part have utilized introduced species of
parasitoids, or entomopathogens (Bacillus thuringiensis Berliner (B.t.), fungi, viruses).
Other aspects of biological control such as mass releases of parasitoids e.g. Trichogramma
species, have been largely neglected. However reports from the USSR,
China, and South American countries have attributed considerable successes with this
approach and are prompting some consideration of initiating similar work in Canada.
Much may depend on the development of techniques to provide a large number of
parasitoids during a relatively short period for any particular insect. The main
emphasis will be on production and storage but consideration should also be given to a
number of target pests whose susceptible stages occur at different times.
Increased awareness of the value of natural enemies has led to research on the
differential effects of pesticides on natural enemies. Although pesticides usually affect
a wide spectrum, some taxa are less affected by them than others. A working group of
the West Palaearctic Regional Section of the International Organization for Biological
Control has taken an organized and coordinated approach to this subject. Members of
this group have standardized the culturing of various taxa of beneficial insects and are
adopting standardized methods for testing the effects of pesticides on these insects in
the laboratory and in the field. Eventually these data will be available as recommendations
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