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276 I. W. Varty
Further research
Literature Cited
males to interfere with the transmission of genes is best exemplified by the successful
screwworm and fruit fly mntrol operations by the United States Department of Agriculture.
During the 1970s many agencies around the world attempted pest control based on this
principle (Whitten & Foster 1975).
Exploratory research on spruce budworm genetics was conducted by CFS in the
late 1970s, the only research agency with a declared interest. Such work is essentially
long-term, demanding of innovation and risky as an investment; it includes investigations of
induced sterility, gene-damaging methods, and procedures for attaining population
control. It may offer opportunities for diminishing the budworm's reproductive success,
but has potential mainly for small areas in the early stages of population increase.
Prospects for early operational application are dim.
Clearly none of the biological methods of control is ready to displace chemical spraying
in a significant percentage of the area needing protection from spruce budworm.
However, B.I. is efficacious and acceptable financially for small areas, especially in high
value stands and in zones where chemicals are prohibited. The technical research, as
recommended by Smirnoff & Morris in this chapter, should be strongly supported,
because B.I. is close to being cost-competitive. It is the only non-chemical method able
to replace the registered chemicals in the event of further restrictions, and it has
considerable international research interest.
For other entomopathogens, the main barrier to progress is the lack of methods for
mass-propagation of agents at acceptable cost. Research agencies should re-examine
the feasibility of hastening such capability, consulting with the many international
agencies interested in similar, but problem-specific, developmental research. Because
the search for new species or virulent strains of known entomopathogens has shown
little promise, the prospects for induced genetic alteration should be monitored by close
contact with scientific advances in agriculture. Meanwhile it is desirable to maintain the
current steady progress reported already in this chapter.
Research on parasitoids and predators is at low ebb. More basic research on hostparasitoid
compatibility and on release and dispersion methods should be conducted.
Research on genetic methods of autocidal control have been exploratory, but results
have been sufficiently encouraging to justify further work.
The contributors to each section of this chapter have recommended further long-term
research. The potential for effective alternatives to chemical control is real, even if slight
in most cases. Except for 8.1., none of these alternatives is likely to have a significant
role in forest protection operations in the 1980s. However, because the spruce budworm
is a long-term problem, and spruce-fir forest is a long-term resource, the need for an
array of protection techniques for both remedial and preventive intervention is likely to
persist.
Beirne. B.P. (1975) Biological control attempts by introductions against pest insects in the field in Canada. Canadian Entomologist
107.225-236.
Ferron. P. (1978) Biological control of insect pests by entomogenous fungi. Annual Review of Entomology 23.409-442.
Finnegan. R.J. (1978) Predation by Formica lugubris (Hymenoptera: Formicidae) on Choristoneura fumiferana (Lepidoptera: Tonricidae).
Canadian Forestry Service Bi-monthly Research Notes. 34(1).3-4.
Miller. C.A.; Vanyo I.W. (1975) Biological methods of spruce budworm control. Forestry Chronicle 51.16-19.
Munroe. E.G. (1971) Status and potential of biological control in Canada. In: Biological control programmes against insects and weeds in
Canada. 1959·68. Commonwealth Institule of Biological Control Technical Communication 4.213-255.
Pschorn-Walchcr. H. (1977) Biological control of forest insects. Annual Review of Entomology 22.1-22.
TInsley. T.W. (1979) The potential of insect pathogenic viruses as pesticidal agents. Annual Review of Entomology 24.63-87.
Whitten. M.J.; Foster. G.G. (1975) Genetic methods of pest control. Annual Review of Entomology 20.461-476.