Environmental Engineering Reference
In-Depth Information
What is integrated pest management?
Insect control is slowly evolving from a reliance on chemical
insecticides to “integrated pest management” that includes
surveillance of pest populations, source reduction, larvicides,
and biological control. Surveillance programs in salt marshes
track adults, larvae, and larval habitats, and only when pest
populations exceed some set level are control activities initi-
ated. Source reduction involves elimination of larval habitats,
and includes open marsh water management and rotational
impoundment management where the marsh is minimally
flooded during the summer by temporary impoundments—
reducing mosquito breeding. Biological control includes the
use of predators to eat mosquito larvae, such as aquatic inver-
tebrates, mosquitofish, and killifish.
What are the effects of pesticides on nontarget organisms?
In the 1960s, predatory birds such as brown pelicans, eagles,
and ospreys in coastal areas of the United States accumulated
such high levels of DDT and related pesticides that they had
reproductive failure and were in danger of becoming extinct
until the chemical was banned in 1970. DDT and related pes-
ticides caused these birds to lay eggs with very thin eggshells,
so that the eggs broke when the birds sat on them, resulting in
reproductive failure.
Toxic effects can be lethal or sublethal. Effects can be docu-
mented in laboratory exposures or observed in organisms in
the field. Effects can be studied at various levels of biological
organization from the molecular level (e.g., effects on enzymes
or DNA), to the organism (e.g., effects on growth, physiology,
behavior, development), to the population (e.g., changes in
population density, birth rate, or age structure), to the com-
munity (e.g., effects on the number of species present). Effects
on the organisms' immune system, endocrine system, nervous
system, reproductive system, and so on are critical. Of great
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