Contents - LAC Biosafety

178 Management of tropical forest insect pests
6. Can the pest be controlled by other less specific biocontrol agents?
Commercial preparations of the bacterial insecticide Bacillus thuringiensis (Bt)
which is effective against a wide range of caterpillar pests are now available.
Prefer an asporogenous preparation of Bt. Bt can kill honey bees, but
asporogenous preparations will not perpetuate the organism in the environment
and will therefore be less harmful to bees. Since there is evidence of development
of resistance to Bt by some pests, Bt may be used as part of an IPM programme,
including use of insecticidal chemicals. Therefore ask the next question.
7. What are the most suitable chemical pesticides and their methods
of application, consistent with least harm to non-target species,
particularly honey bees?
In choosing an insecticide for use in the forest, care should be taken to choose
one which is not only effective against the pest but also meets certain other
criteria. The most important is the safety of non-target organisms. Newer
insecticides like the chitin inhibitor diflubenzuron act by inhibiting chitin
synthesis and is therefore safe to several other groups of organisms. Also choose
those chemicals which are comparatively less toxic to honey bees. Data on
toxicity rating for honey bees is available for most pesticides. Honey bees
and other bee pollinators are important components of the forest ecosystem.
Their protection is important since forest plantations cover much larger
contiguous areas compared with agriculture.
Conventional spraying equipments are suitable only for young plantations.
There is a need to develop suitable machinery for applying pesticides to tall
trees, not only for chemicals but also for biopesticides. Use low-volume or
Box 9.1 Protection of stored timber
The methods used for protection will depend on the kind of wood and the
purpose for which it is to be used. Apart from the use of resistant timber
species to avoid pest problems, two broad categories of protection methods
are available – (1) physical methods and (2) chemical methods. Each of these
has its merits and demerits and it is often possible to combine some of the
methods.
Use of pest-resistant timber
Pest problems can be avoided if pest-resistant timbers are used.
However, there is no timber which is absolutely resistant to insect pests,