In spite of widespread public concern for long-term
health and environmental e!ects of synthetic pesticides,
especially in Europe and North America, natural pesticides,
both of microbial and plant origin, have yet to have
much impact in the marketplace. Bioinsecticides, dominated
by Bacillus thuringiensis-based products, and botanical
insecticides, dominated by pyrethrum-based
products, each command little more than 1% of the
global insecticide market. However, recent government
action in the United States, in the form of the Food
Quality Protection Act of 1996, will dramatically restrict
the use of many conventional insecticides upon which
growers have depended for decades (e.g. organophosphates
and carbamates). In turn, this will create a signi"-
cant market opportunity for alternative products, in
particular `reduced-riska pesticides which are favored by
the Environmental Protection Agency in the USA.
Against this backdrop, natural pesticides based on
plant-essential oils may represent alternative crop protectants
whose time has come. Essential oils, obtained by
steam distillation of plant foliage, and even the foliage
itself of certain aromatic plants (notably in the families
Myrtaceae and Lamiaceae, but in other plant families as
well) have traditionally been used to protect stored grain
and legumes, and to repel #ying insects in the home.
Though some of the claimsmade for these crude preparations
have yet to be substantiated through controlled
experiments, scienti"c investigation into the biological
activities of these materials proliferated in the past decade.
The emerging picture is that certain, speci"c oils and
their chemical constituents have demonstrable contact
and fumigant toxicity to a number of economically important
insect and mite pests, as well as to plant pathogenic
fungi.