Most insect pests of crops, livestock, and man
have been easily controlled for the past 35 years by
relatively inexpensive organochlorine and organophosphorus
compounds and methylcarbamates.
Control of pest insects is progressively more difficult
and costly because of increasing restrictions on some
of the major insecticides of these types. They are
considered to have unfavorable persistence. environmental
impact and/or toxic effects on higher
animals including man. There is an urgent need for
alternative chemical or biological control methods
for pest control. Pyrethroids developed within the
past seven years are helping to meet this need. These
insecticides are structural modifications of one of the
oldest insect control agents, the remarkably effective
but unstable pyrethrins from pyrethrum flowers.
The newer pyrethroids have greatly improved potency
and stability. It is appropriate as the use of
pyrethroids expands to examine their origin,
properties and safety aspects as compared with the
pyrethrins and their prospects for filling current and
projected gaps in insect control capabilities.
Pest insect control until the 1940's was moderately
successful with the use of primarily compounds from
natural sources either directly or after simple extractions
or other treatments. These "first generation"
insecticides were inorganic arsenic- or fluorine-containing
toxicants or botanicals such as
nicotine, rotenone, and pyrethrins. Except for the