Application of Biodegradable Pesticides in India
283
poor in comparison to pyrethrin when it was tested against mosquitoes, houseflies, flour beetles, and woolly bears. The seed oil failed to control mosquitoes
and flour beetles as a contact insecticide.
The seed oil and leaf extract of Azadirachta indica L. (Indian neem) also
did not kill flies, mosquitoes, floor beetles, and wool-destroying insects. However, the nonfatty alcohol extract of the neem seed cake showed aphicidal activity
(Sinha and Gulati, 1968). Nutmeg leaf oil (Myristicafragraus Hout.) was relatively toxic to flies and mosquitoes but was ineffective against woolly bears.
Petroleum ether extracts of roots, stem, and leaves of Abrus precalorius L. (wild
liquorice root), and Nerium odorum Soland (sweet scented oleander) were not
very toxic to flies and mosquitoes, whereas the extracts of Curcuma long L.
(turmeric) and Andropogen citrulus D.C. (lemon grass oil) were found to be
toxic to insects (Anonymous, 1951, 1954, 1964, 1965).
10.8. PESTICIDES IN FORESTRY
Forests constitute one of the most important natural wealths of any country.
Besides valuable timber, they yield a variety of products of great economic
importance. Forests in India are covered by several very valuable kinds of trees,
in addition to a variety of medicinal plants and wild life. Teak (Tectona grandis),
shisham (Dalbergia sisso), gamtar (Gmelina arborea), deodar (Cedrus deodar),
sal (Shorea robusta), mahogany (Seietenia macrophylla), oak (Quecrus incana),
sandal (Santalum album), Causurina, neem (A. indica L.), and bamboo are some
of the forest trees which have helped sustain the forest wealth for ages. Large
tracts of forest also have a direct influence on the local rainfall.
Forests play an important role in the national economy. Their destruction
or deforestation is a matter of serious concern. The area of forests in India
comprises 783,692 km 2 (302,688 square miles) and is unevenly distributed.
Insects, in addition to other factors, are one of the greatest agents of destruction
of forests. Because of their high rate of reproduction and short life cycles, most
forest insects have the ability to multiply to astronomical numbers. In nature,
such optimum conditions do not exist because they are offset by destructive
influences such as climate, weather, availability of food, prevalence of diseases,
and other enemies which destory insects. The importance of various other agencies varies at different times and densities, but all are interdependent to a great
extent. Under normal conditions, control is maintained by such natural factors,
and a state of equilibrium prevails in the natural forest for all the populations
constituting the fauna of the forest. When environmental conditions favor rapid
increase of destructive pests, natural control factors are incapable of checking
the outbreak and widespread damage often results.
In the widest sense, forest operations with pesticides destory the stable
283
poor in comparison to pyrethrin when it was tested against mosquitoes, houseflies, flour beetles, and woolly bears. The seed oil failed to control mosquitoes
and flour beetles as a contact insecticide.
The seed oil and leaf extract of Azadirachta indica L. (Indian neem) also
did not kill flies, mosquitoes, floor beetles, and wool-destroying insects. However, the nonfatty alcohol extract of the neem seed cake showed aphicidal activity
(Sinha and Gulati, 1968). Nutmeg leaf oil (Myristicafragraus Hout.) was relatively toxic to flies and mosquitoes but was ineffective against woolly bears.
Petroleum ether extracts of roots, stem, and leaves of Abrus precalorius L. (wild
liquorice root), and Nerium odorum Soland (sweet scented oleander) were not
very toxic to flies and mosquitoes, whereas the extracts of Curcuma long L.
(turmeric) and Andropogen citrulus D.C. (lemon grass oil) were found to be
toxic to insects (Anonymous, 1951, 1954, 1964, 1965).
10.8. PESTICIDES IN FORESTRY
Forests constitute one of the most important natural wealths of any country.
Besides valuable timber, they yield a variety of products of great economic
importance. Forests in India are covered by several very valuable kinds of trees,
in addition to a variety of medicinal plants and wild life. Teak (Tectona grandis),
shisham (Dalbergia sisso), gamtar (Gmelina arborea), deodar (Cedrus deodar),
sal (Shorea robusta), mahogany (Seietenia macrophylla), oak (Quecrus incana),
sandal (Santalum album), Causurina, neem (A. indica L.), and bamboo are some
of the forest trees which have helped sustain the forest wealth for ages. Large
tracts of forest also have a direct influence on the local rainfall.
Forests play an important role in the national economy. Their destruction
or deforestation is a matter of serious concern. The area of forests in India
comprises 783,692 km 2 (302,688 square miles) and is unevenly distributed.
Insects, in addition to other factors, are one of the greatest agents of destruction
of forests. Because of their high rate of reproduction and short life cycles, most
forest insects have the ability to multiply to astronomical numbers. In nature,
such optimum conditions do not exist because they are offset by destructive
influences such as climate, weather, availability of food, prevalence of diseases,
and other enemies which destory insects. The importance of various other agencies varies at different times and densities, but all are interdependent to a great
extent. Under normal conditions, control is maintained by such natural factors,
and a state of equilibrium prevails in the natural forest for all the populations
constituting the fauna of the forest. When environmental conditions favor rapid
increase of destructive pests, natural control factors are incapable of checking
the outbreak and widespread damage often results.
In the widest sense, forest operations with pesticides destory the stable