284
c. R. Krishna Murti and T. S. S. Dikshith
equilibrium of the undisturbed environment and produce a new one, which may
be temporarily stable but which often permits multiplication of plant feeders to
an injurious degree. This disturbance reaches its extreme degree in large monospecific plantations in which the population of the pest and its natural enemies
are widely out-of-balance. The incidence of the pest is either maintained at a
high level or is subject to oscillations in the form of epidemics alternating with
scarcity (Mathur, 1964).
To quote Beeson (1941), "Indian forestry is not static ... it is experimental
and progressive and is continually producing new conditions under which wellknown pests create fresh ecological problems and unknown insects spring into
prominence as pests." The control of forest insects is therefore not a simple
problem. The forest is faced continually with insect problems at every stage in
the growth of the tree, coniferous or deciduous. Before the seeds are collected,
they may be destroyed by certain insects. The insect damage continues even
during storage of seeds. The seedlings, saplings, and trees in the forest are
injured by defoliators and sapsuckers, girdled by bores, or killed by root-eating
insects. This ability of insects to attack the tree in all phases of its growth greatly
influences the practice of forestry both directly and indirectly.
The spike diseases of sandal (S. album) cause a hugh loss of forest revenue
in Kamataka, Tamil Nadu, and parts of the Kerala States. The disease is caused
by a virus and four species of insects. J assus indicus Walker, M oonia varlabilis
Distent, Petalocephala uniformin Distant, and Sarima nigro clypeata Meliacher
are the vectors of the viral disease. It is a matter of great concern that no chemical
control has thus far been found to combat this deadly disease.
A variety of insect pests cause damage and loss of the forest trees. It has
not been possible to control the attack of insects with anyone kind of insecticide.
However, several workers have suggested treating the infected parts of the trees
with DDT, endrin, BHC, dieldrin dusts and sprays, injections of a mixture of
creosote and fuel oil, and pentachlorophenol as prophylactic measures before the
onset of the monsoon or rainy season.
Chemical control methods should be supplemented with appropriate silvicultural practices like mixed plantations of trees to minimize the pest population
in forests.
10.9. SAFETY EVALUA TION STUDIES
10.9.1. Toxicity to Fish
The indiscriminate use of pesticides in agriculture and public health operations has widened the scope of disruption of the ecological balance as many
of the nontarget and beneficial organisms, which include important members of
c. R. Krishna Murti and T. S. S. Dikshith
equilibrium of the undisturbed environment and produce a new one, which may
be temporarily stable but which often permits multiplication of plant feeders to
an injurious degree. This disturbance reaches its extreme degree in large monospecific plantations in which the population of the pest and its natural enemies
are widely out-of-balance. The incidence of the pest is either maintained at a
high level or is subject to oscillations in the form of epidemics alternating with
scarcity (Mathur, 1964).
To quote Beeson (1941), "Indian forestry is not static ... it is experimental
and progressive and is continually producing new conditions under which wellknown pests create fresh ecological problems and unknown insects spring into
prominence as pests." The control of forest insects is therefore not a simple
problem. The forest is faced continually with insect problems at every stage in
the growth of the tree, coniferous or deciduous. Before the seeds are collected,
they may be destroyed by certain insects. The insect damage continues even
during storage of seeds. The seedlings, saplings, and trees in the forest are
injured by defoliators and sapsuckers, girdled by bores, or killed by root-eating
insects. This ability of insects to attack the tree in all phases of its growth greatly
influences the practice of forestry both directly and indirectly.
The spike diseases of sandal (S. album) cause a hugh loss of forest revenue
in Kamataka, Tamil Nadu, and parts of the Kerala States. The disease is caused
by a virus and four species of insects. J assus indicus Walker, M oonia varlabilis
Distent, Petalocephala uniformin Distant, and Sarima nigro clypeata Meliacher
are the vectors of the viral disease. It is a matter of great concern that no chemical
control has thus far been found to combat this deadly disease.
A variety of insect pests cause damage and loss of the forest trees. It has
not been possible to control the attack of insects with anyone kind of insecticide.
However, several workers have suggested treating the infected parts of the trees
with DDT, endrin, BHC, dieldrin dusts and sprays, injections of a mixture of
creosote and fuel oil, and pentachlorophenol as prophylactic measures before the
onset of the monsoon or rainy season.
Chemical control methods should be supplemented with appropriate silvicultural practices like mixed plantations of trees to minimize the pest population
in forests.
10.9. SAFETY EVALUA TION STUDIES
10.9.1. Toxicity to Fish
The indiscriminate use of pesticides in agriculture and public health operations has widened the scope of disruption of the ecological balance as many
of the nontarget and beneficial organisms, which include important members of