| Some biologists have called this the "Age of Insects".
Among animals, certainly the diversity of insects is
unrivaled. Nearly one million species have been
described to date, and some entomologists estimate
that as the tropics are fully explored, we will find
that there are actually more than three million insect
species. The large number of insects is often attributed
to the divergence of plants (angiosperms), which provide
numerous hosts and places to feed, but if plant feeders
are excluded from the tabulation the biodiversity of
insects remains unrivaled. Virtually every environment
has been exploited by these resilient organisms. Even
if one dislikes insects, they are impossible to ignore,
and a little knowledge about them could be indispensable
should one have a close encounter' of an unpleasant kind.
Insects are remarkable biological organisms. They are
small enough to escape the detailed scrutiny of most
people, but I have yet to meet anyone whom, once provided
the opportunity to examine insects closely (through a
microscope) is not completely amazed by the detail and
complexity of these exquisitely designed (by natural
selection) beasties. They are fascinating in function
as well as form. Insects are the only invertebrates to
fly, they are disproportionately strong, and their
ecological adaptability defies belief For example, some
insects produce their own version of anti-freeze, which
allows them to be frozen solid yet to regain normal
function upon thawing. Their sensory abilities are beyond
human comprehension; a male insect can sometimes locate
a female by her "perfume" (pheromone) from several
kilometers distance. Although not normally considered
intelligent, insects display surprisingly complex
behaviors, and altruistic social systems that could well
serve as models for human societies.
Insects and their close relatives are important for many
reasons besides their sheer diversity. Their effect on
humans is profound. Insects are our chief competitor for
food and fiber resources throughout the world. Annual crop
losses of 10 to 15% are attributed to insects, with both
pre-harvest and post-harvest losses considerably more at
times. Insects also are the principal vector of many human,
animal, and plant diseases, including viruses, mollicutes,
bacteria, fungi, and nematodes. The ability to transmit
diseases magnifies their effect, and makes it more difficult
to manage injury. Over the course of human history, insect-
transmitted disease has caused untold human suffering. For
example, introduction of flea-transmitted bubonic plague to
Europe centuries ago killed millions of people and caused
severe disruption to western civilization. Though less
dramatic, mosquito-transmitted malaria kills thousands
annually throughout the world, and unlike plague, which is
now mostly a historical footnote, the toll continues to
mount.
Advances in technology, particularly the introduction
of chemical insecticides, have done much to remove the
threat of insect-related damage from the consciousness of
most humans. Insecticides are applied preventatively to
avoid pre- and post-harvest damage to crops, to our
dwellings, and to our landscape. This is an oft-overlooked
but remarkable achievement that has increased stability in
the supply and price of resources, and in the lives of
resource producers. No longer are people faced with
starvation or economic ruin due to the ravages of insects;
in almost all parts of the world, the ready availability
of insecticides can be used to prevent massive insect
population outbreaks. However, we realize increasingly
that this approach is not without its own set of health,
environmental and economic costs, and alleviating
dependency on insecticides, or making alternatives to
insecticides more readily available, has assumed greater
priority.
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